ISTANBUL TECHNICAL UNIVERSITY  GRADUATE SCHOOL OF SCIENCE

ENGINEERING AND TECHNOLOGY

RELIABILITY AVALIABILITY AND MAINTAINABILITY ANALYSIS

IN NAVAL SHIPS

M.Sc. THESIS

Oğuz AKKAYA

Department of Naval Architecture and Ocean Engineering

Marine Engineering Programme

Anabilim Dalı : Herhangi Mühendislik, Bilim

Programı : Herhangi Program

JANUARY 2013
ISTANBUL TECHNICAL UNIVERSITY  GRADUATE SCHOOL OF SCIENCE
ENGINEERING AND TECHNOLOGY

RELIABILITY AVALIABILITY AND MAINTAINABILITY ANALYSIS

IN NAVAL SHIPS

M.Sc. THESIS

Oğuz AKKAYA
(508081011)

Department of Naval Architecture and Ocean Engineering

Marine Engineering Programme

Thesis Advisor: Prof. Dr. Oğuz Salim SÖĞÜT

Anabilim Dalı : Herhangi Mühendislik, Bilim
Programı : Herhangi Program

21 January 2013
İSTANBUL TEKNİK ÜNİVERSİTESİ  FEN BİLİMLERİ ENSTİTÜSÜ

SAVAŞ GEMİLERİNDE RAM ANALİZİ

YÜKSEK LİSANS TEZİ

Oğuz AKKAYA
(508081011)

Gemi İnşa ve Gemi Makineleri Anabilim Dalı

Gemi Makineleri Programı

Tez Danışmanı: Prof. Dr. Oğuz Salim SÖĞÜT

Anabilim Dalı : Herhangi Mühendislik, Bilim
Programı : Herhangi Program

OCAK 2013
Oğuz AKKAYA, a M.Sc student of ITU Graduate School Of Scıence Engıneerıng
And Technology student ID 508081011, successfully defended the thesis entitled
“RELIABILITY AVALIABILITY AND MAINTAINABILITY ANALYSIS IN
NAVAL SHIPS”, which he prepared after fulfilling the requirements specified in the
associated legislations, before the jury whose signatures are below.

Thesis Advisor : Prof. Dr. Oğuz Salim SÖĞÜT ..............................

İstanbul Technical University

Jury Members : Prof. Dr. Osman Azmi ÖZSOYSAL .............................

İstanbul Technical University

Prof. Dr. Deniz ÜNSALAN ..............................

Piri Reis University

Date of Submission : 17 December 2012

Date of Defense : 21 January 2013

v
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 To my son Tuna and my wife Ayten ,

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viii
FOREWORD

Through the thesis, RAM Analysis is conducted for an auxiliary ship class in Turkish
Navy. I acknowledge Turkish Navy HQ for the permission to inquire failure data of
that ship class and also to publish the results.
I also acknowledge ISOGRAPH who supplied the software RWB 11.0, free of
charge, for designing the ship system and calculating the results evaluated with an
academic license for a period of six months.

December 2012 Oğuz AKKAYA

ix
x
TABLE OF CONTENTS

Page

FOREWORD ............................................................................................................. ix
TABLE OF CONTENTS .......................................................................................... xi
ABBREVIATIONS ................................................................................................. xiii
LIST OF TABLES ................................................................................................... xv
LIST OF FIGURES ............................................................................................... xvii
SUMMARY ............................................................................................................. xix
ÖZET........................................................................................................................ xxi
1. INTRODUCTION .................................................................................................. 1
1.1 Purpose of Thesis ............................................................................................... 1
1.2 7 Literature Review ............................................................................................ 2
1.3 Applications of RAM Analysis .......................................................................... 4
2. DEFINITIONS ....................................................................................................... 7
2.1 Reliability ........................................................................................................... 7
2.2 Maintainability ................................................................................................... 7
2.3 Availability ......................................................................................................... 8
2.4 Redundancy ........................................................................................................ 9
2.5 Mean Time Between Failures (MTBF) .............................................................. 9
2.6 Mean Time To Failure (MTTF) ......................................................................... 9
2.7 Mean Time To Repair (MTTR) ......................................................................... 9
3. RELIABILITY ..................................................................................................... 11
3.1 Reliability Mathematics ................................................................................... 11
3.2 Redundancy ...................................................................................................... 12
3.3 System Structures ............................................................................................. 12
3.3.1 Series systems ........................................................................................... 12
3.3.2 Parallel system .......................................................................................... 13
3.3.3 K-out-of-n systems .................................................................................... 14
3.4 Failure rate........................................................................................................ 14
3.5 Mean time between failures (MTBF) ............................................................... 15
3.6 Mean time to failure (MTTF) ........................................................................... 15
3.7 Mean time to repair (MTTR) ........................................................................... 15
3.8 Reliability ......................................................................................................... 15
4. FAULT TREE ANALYSIS (FTA) ..................................................................... 17
4.1 Benefits To Be Gained From FTA ................................................................... 17
4.2 System Definition ............................................................................................. 18
4.3 Fault Tree Construction .................................................................................... 19
4.4 Qualitative Fault Tree Evaluation .................................................................... 20
4.5 Quantitative Fault Tree Evaluation .................................................................. 20
5. SCOPE OF THE THESIS ................................................................................... 23
5.1 Assumptions ..................................................................................................... 24
5.2 Utilization of Isograph Reliability Workbench 11.0. ....................................... 24

xi
 5.3 Isograph Reliability Workbench 11.0. Calculations......................................... 27
5.3.1 Unavailability of a component (Q) and component failure frequency (ω)
............................................................................................................................ 27
5.3.2 Unavailability of a sub-system and system (Qsys) ..................................... 28
5.3.3 Cut sets occurance probability (Qcut) ........................................................ 29
6. TOTAL SHIP RELIABILITY ANALYSIS ....................................................... 31
6.1 MTTF-MTTR Calculations .............................................................................. 31
6.2 Unavailability Calculations .............................................................................. 31
6.3 Results and Discussion ..................................................................................... 32
6.3.1 Unavailability of main sub-systems .......................................................... 33
6.3.2 Number of expected failures of main sub-systems ................................... 34
6.3.3 Unreliability of main sub-systems............................................................. 34
6.3.3.1 Contribution of propulsion sub-system .............................................. 35
6.3.3.2 Contribution of steering gear sub-system........................................... 39
6.3.3.3 Contribution of electric power sub-system ........................................ 40
6.3.3.4 Contribution of damage control sub-system ...................................... 44
7. FAULT TREE CONSTRUCTION ..................................................................... 47
8. CONCLUSIONS................................................................................................... 49
8.1 Unavailability Results ...................................................................................... 49
8.2 Unreliability Results ......................................................................................... 50
8.3 Suggestions ....................................................................................................... 50
REFERENCES ......................................................................................................... 51
APPENDICES .......................................................................................................... 53
APPENDIX G ........................................................................................................... 55
APPENDIX I ........................................................................................................... 105
CURRICULUM VITAE ........................................................................................ 131

xii
ABBREVIATIONS

CDF : Cumulative Distribution Function

FMEA : Failure Mode and Effectiveness Analysis
FT : Fault Tree
FTA : Fault Tree Analysis
GENSET : Generator Set
MTBF : Mean Time Between Failures
MTTF : Mean Time To Failure
MTTR : Mean Time To Repair
PDF : Probability Distribution Function
RAM : Reliability Availability Maintainability
RBD : Reliability Block Diagram
RWB : Reliability Workbench
SNAMEA : Society of Naval Architects and Marine Engineers
S/G : Steering Gear
TDT : Total Down Time
UKAEA : United Kingdom Atomic Energry Authority

xiii
xiv
LIST OF TABLES

Page

Table 6.1 : Propulsion system result summary. ....................................................... 36

Table 6.2 : Steering Gear System Result Summary. ................................................ 39
Table 6.3 : Electric power sub-system’s result summary. ........................................ 40
Table 6.4 : Damage control sub-system result summary. ........................................ 44
Table 7.1 : RBD and FT analaysis results. ............................................................... 47

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LIST OF FIGURES

Page

Figure 3.1 : Series System. ....................................................................................... 12

Figure 3.2 : Parallel System. ..................................................................................... 13
Figure 4.1 : FTA Construction Steps. ...................................................................... 18
Figure 4.2 : FTA Example. ...................................................................................... 20
Figure 4.3 : Minimum Cut Set 1. ............................................................................. 21
Figure 4.4 : Minimum Cut Set 2. ............................................................................. 21
Figure 5.1 : Ship SystemRBD. ................................................................................. 23
Figure 5.2 : RBD construction example. ................................................................. 25
Figure 5.3 : Failure model window. ......................................................................... 26
Figure 5.4 : Faul tree example. ................................................................................ 27
Figure 5.5 : Simple series arrangement. ................................................................... 28
Figure 5.6 : Simple parallel arrangement. . ............................................................... 29
Figure 6.1 : Unavailability of main sub-systems. . ................................................... 33
Figure 6.2 : Number of expected failures of main sub-systems. .............................. 34
Figure 6.3 : Unreliability of system. . ....................................................................... 35
Figure 6.4 : Unreliabilities of main sub-systems. . ................................................... 36
Figure 6.5 : Main Engine No:1 unavailability diagram. . ......................................... 37
Figure 6.6 : Main Engine No:2 unavailability diagram. . ......................................... 37
Figure 6.7 : Main Engine No:1 unreliability-time diagram. . ................................... 38
Figure 6.8 : Main Engine No:2 unreliability-time diagram. .................................... 38
Figure 6.9 : Unreliability of steering gear sub-system. ............................................ 39
Figure 6.10:Unavailabilities of electric power sub-systems. ................................... 40
Figure 6.11:Unreliabilities of electric power sub-systems. ...................................... 41
Figure 6.12:GENSET No:1 unavailability. .............................................................. 42
Figure 6.13:GENSET No:1 unreliability. ................................................................ 42
Figure 6.14:GENSET No:2 unavailability. .............................................................. 43
Figure 6.15:GENSET No:2 unreliability. ................................................................ 43
Figure 6.16:Damage control unavailability. ............................................................ 44
Figure 6.17:Damage control unreliability. ............................................................... 45

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 RELIABILITY AVALIABILITY AND MAINTAINABILITY ANALYSIS

IN NAVAL SHIPS

SUMMARY

Reliability Availability and Maintainability (RAM) analysis is performed to predict

availability of a system in the future and to make amendments which will increase
the performance of an equipment where necessary. Ram analysis has been used for
many years by companies to decrease the number of failures of the equipments
especially in warranty period.
Naval ships have various missions to accomplish. In order to accomplish the mission,
ship availability should be considered with utmost importance. To identify the
availability and reliability of a ship, failure rates of ship’s components are used. Ram
analysis computed by failure rates may be helpful for decision-makers in
modernizing the ship equipments. Equipments which have lower reliability and
availability, may be exchanged or may be modernized in order to increase the
performance of the equipment and availability of the ship.
In order to maintain the availability, i.e., ship may continue to accomplish the
missions assigned, Naval Ships should go through reliability, availability and
maintainability analysis during both building and life cycle. Through Ram Analysis,
components and systems, which reduce the availability of a ship, may be determined.
Reliability and safety methods experienced a rapid development after the Second
World War. These methods were mainly concerned with military use for electronics
and rocketry studies. The first predictive reliability models appeared in Germany on
the V1 missile project where a reliability level was successfully defined from
reliability requirements and experimentally verified on components during their
development stages. The first formal approach to shipboard reliability was the
Buships specification, MIL-R-22732 of July 31, 1960, prepared by the United States
of America’s Department of Defence and addressed ground and shipboard electronic
equipment. After the success gained by RAM Analysis in military area, RAM
analysis has been used by commercial purposes. Producers needed to improve the
reliability of their items in order to seize the confidence of customers.
In this thesis, some of auxiliary class ships have been examined through the failures
occurred between two overhauls. Reliability, availability and maintainability of the
systems are calculated on component basis by the help of a commercial software
named as Isograph Reliability Workbench. Reliability Block Diagram (RBD) has
been prepared and analyzed.
Components affecting the availability of the ship are reported. This information may
be used to decide whether these systems or components should be replaced with
better systems or components. In this thesis, also a Fault Tree Analysis (FTA) is

xix
carried out manually in order to help ship crew in finding the reasons of common
failures which may occur in ships.
Results of RBD and FTA analysis are compared, and it is observed that they agree
very well. The results include unavailability of system, failure frequency,
unreliability, total down time of system and expected number of failures. While
unreliability of system increases with working hours, unavailability of system does
not change.

xx
 SAVAŞ GEMİLERİNDE RAM ANALİZİ

ÖZET

İngilizcede Reliability, Availability and Maintainability (RAM) analizi olarak

kullanılan metod dilimizde Güvenilirlik, Kullanılabilirlik ve Sürdürülebilirlik
Analizi olarak yer bulmaktadır.
RAM analizinin yapılış amacı, bir sistemin gelecekte sahip olacağı kullanılabilirliği
önceden tahmin ederek, eğer ihtiyaç varsa sistemde yapılmasının faydalı olacağı
değerlendirilen değişiklikleri tespit edip, bu değişikliklerin uygulanıp
uygulanmaması konusundaki kararlara destek sağlamaktır. RAM analizi uzun
yıllardır firmalarca kullanılmaktadır. Firmalar dizayn ve üretim süreçleri içerisinde
RAM analizine yer vermektedirler.
RAM analizi ile firmalar ürettikleri ürünlerin tüketicilere sunulduktan sonra,
minimum sayıda veya hiç arıza yapmadan kullanım ömürlerini tamamlamalarını
hedeflemektedirler. Bu maksatla ürünün çok fazla sayıda arıza yaptığı başlangıç
periyodunu tüketiciye sunmadan önce fabrika ortamında tamamlamakta, arıza
oranının neredeyse sabit hale geldiği kullanım ömrü periyodunda ürünü tüketiciye
sunmaktadırlar. Bu şekilde firmaya ait ürün çok fazla sayıda meydana gelecek arıza
nedeniyle piyasada kötü bir üne sahip olmamaktadır. Firma yaptığı RAM analizi
sonucunda ürünün kullanım ömrünün başlangıcını tespit ederek tüketiciye sunulacağı
zamanı kararlaştırmaktadır. Piyasada ise tüketiciler o firmaya ait ürünlerin az arıza
yaptığı imajına sahip olacaklarından, firmaya ait ürünler daha fazla tercih edilir hale
gelecektir.
Güvenilirlik ve güvenlik konusundaki çalışmalar özellikle II.Dünya Savaşı’ndan
sonra hız kazanmıştır. Bu çalışmalar genellikle elektronik cihazlar ve roket
teknolojileri ile ilgili olarak yapılmaktaydı. Bu konuda güvenilirlik seviyesinin tam
olarak tespit edildiği ve tespit edilen değerlerin deneylerle sistem bileşenlerinde ispat
edildiği ilk çalışma olarak Almnya’da V1 füzelerinin üretiminde uygulamaya
konulan RAM analizi sayılabilir. Ram analizi uygulamalarında ilk resmi uygulama
ise, 1960 yılında Amerikan Savunma Bakanlığı tarafından elektronik cihazların
güvenilirliği konusunda hazırlanan “Buships Spefications, MIL-R- 22732”dir. ABD
savunma bakanlığı ve NASA RAM analizi kullanımının yaygınlaşmasında bir tür
öncü rolü üstlenmiştir. Füze ve uzay teknolojileri ile üretilen ürünler onarılabilirlik
açısından zayıf olduklarından, üretim ve dizayn aşamasında yapılan RAM analizi ile
ürün kullanıldıktan sonra ortaya çıkması muhtemel tüm arızaların önlenmesi
amaçlanmıştır. Füze ateşlendikten sonra elektronik kartlardan birinde çıkacak bir
arızanın onarımı mümkün olmadığından, füze ateşlenmeden önce muhtemel
arızaların engellenmesi büyük önem taşımaktadır.
NASA ve Amerikan Savunma Bakanlığı tarafından öncülüğü yapılan RAM analizi
uygulamaları daha sonra sivil endüstriler tarafından da benimsenmiştir. Günümüzde
beyaz eşya üreticilerine kadar bir çok sektörde dizayn ve üretim aşamalarında
yapılan RAM analizi ile ürünler daha az arıza oranları ile tüketicilere sunulmaktadır.
xxi
Savaş gemilerine gerçekleştirmek üzere çok çeşitli görevler verilmektedir. Bu
görevler verildiği anda geminin bu görevi gerçekleştirmeye hazır bulunması
gereklidir. Savaş gemilerinin kullanılabilirliği bu aşamada önemlidir.
Kullanılabilirliğin arttırılması için savaş gemilerini oluşturan bileşenlerin RAM
analizine tabi tutulmaları gereklidir. RAM analizi yöntem olarak, dizayn ve test
aşamalarında gerçekleştirilerek, üretime geçmeden önce ileride sistemlerin
kullanılabilirliğini olumsuz etkileyecek parametrelerin tespit edilmesi ve
iyileştirmelere gidilmesi şeklinde uygulanabileceği gibi, gemi yaşam periyodunda
meydana gelen arızalar istatiksel olarak incelenerek RAM analizi yapılması ve
gerekli iyileştirmelerin yapılması da mümkündür. Bu analizler sonrasında karar
vericiler güvenilirliği ve kullanılabilirliği olumsuz etkileyen sistemlerin
modernizasyonuna veya kullanımdan kaldırılmalarına karar verebilirler.
Bu tezde Türk Deniz Kuvvetlerine ait yardımcı sınıf olarak görev yapan 5 eş gemi
çalışma konusu yapılmıştır. Bu gemilerin iki overhol onarımı arasındaki arıza
kayıtları incelenerek, gemi tipine ait genel bir güvenilirlik ve kullanılabilirlik
değerlendirmesi yapılmıştır.
Öncelikle bir yardımcı sınıf askeri geminin görev ihtiyaçlarını yerine getirebilmesi
için gerekli olan minimum sistemler göz önüne alınarak bir gemi sistemi
oluşturulmuştur. Bu geminin ana sistemleri olarak ana tahrik sistemi, elektrik üretim
sistemi, dümen sistemi ve yara savunma sistemi ele alınmıştır. Bu dört sistemden
birinin arızalanması durumunda geminin görev yapamayacağı değerlendirilmiştir.
Beş geminin iki overhol arası arızaları incelenmiş, her bir cihazın en fazla sayıda
arıza yapanı seçilmek suretiyle beş gemi en çok arıza yapan cihazlardan oluşan sanal
bir gemi olarak düşünülmüştür. Bu şekilde elde edilecek sonuçların en kötü
senaryoyu ortaya koyacağı değerlendirilmiştir.
Analizin yapılmasında Isograph firması tarafından verilen akademik lisans
kullanılarak, Reliability Workbench 11.0 ticari programı kullanılmıştır. Programda
öncelikle RBD modülünde gemi sistemi oluşturulmuştur. Daha sonra sistemin alt
sistemleri ve alt sistemlerin kullanılabilirliğini etkileyen olaylar RBD modülüne
eklenmiştir. Kullanılabilirliği etkileyen her bir olayın arıza modelleri, geçmişte
meydana gelen arızalardan hesaplanan MTTF ve MTBF değerleri girilerek
oluşturulmuştur. Isograph RWB tarafından, oluşturulan sistem ve arıza modelleri
doğrultusunda analiz yapılarak, gerek alt sistemlerin, gerekse ana sistemlerin
güvenilirlik, kullanılabilirlik değerleri hesaplanmış ve raporlanmıştır. Geminin görev
yapmasını etkileyecek arızaların işlendiği bir hata ağacı FT modülünde hazırlanarak
bu modülle de hesaplama yaptırılmış ve sonuçlar karşılaştırılmıştır.
Elde edilen sonuçlar gemi tipinin kullanılabilirlik açısından tatmin edici seviyede
olduğunu göstermiştir. Güvenilirlik analizinde güvenilirliğin zamanla azaldığı tespit
edilmiştir. Bu sorunun iki overhol arası süreyi azaltarak giderilebileceği
vurgulanmakla birlikte, gemilerin kullanılabilirlik oranlarının yüksekliği nedeniyle
sadece önemli cihazlarda yapılacak koruyucu ve ara bakımlarla yetinilebileceği
değerlendirilmiştir.

xxii
1. INTRODUCTION

Reliability, Availability and Maintainability (RAM) analysis is performed to predict

availability of a system in the future and to make amendments which will increase
the performance of the system. RAM analysis has been used for many years by
companies to decrease the number of failures of the equipments especially in
warranty period.

Naval ships have various missions to accomplish. In order to accomplish the mission,
ship availability should be considered with utmost importance. To determine
availability and reliability of the ship, failure rates of ship’s components are used.
Ram analysis computed by failure rates may be helpful for decision-makers in
modernizing the ship equipments. Equipments which have lower reliability and
availability, may be replaced or modernized in order to increase the performance of
the equipment and availability of the ship.

1.1 Purpose of Thesis

In order to maintain the availability, i.e., ship may continue to accomplish the
missions assigned, Naval Ships should go through reliability, availability and
maintainability analysis during both building and life cycle. Through Ram Analysis,
components and systems, which reduce the availability of ship, can be determined.
In this thesis, some of auxiliary class ships have been examined through the failures
occurred between two overhaul. Reliability, availability and maintainability of the
systems are calculated on component basis by the help of a commercial software.
Components affecting the availability of the ship are reported. This information may
be used to decide whether these systems or components should be replaced with
better systems or components.

In this thesis a Fault Tree Analysis (FTA) is carried out to help ship crew in finding
the reasons of common failures which may occur in ships.

1
1.2 7 Literature Review

Reliability and safety methods experienced a rapid development after the Second
World War. These methods were mainly concerned with military use for electronics
and rocketry studies. The first predictive reliability models appeared in Germany on
the V1 missile project where a reliability level was successfully defined from
reliability requirements and experimentally verified on components during their
development stages (Bazovsky, 1961).

The first formal approach to shipboard reliability was the “Buships Specification,
MIL-R-22732” of July 31, 1960, prepared by the United States of America’s
Department of Defence and addressed ground and shipboard electronic equipment.
Subsequently in 1961 the Bureau of Weapons issued the MIL standards concerning
reliability models for avionics equipment and procedures for the prediction and
reporting of the reliability of weapon systems. This was due to the fact that the
growing complexities of electronic systems were responsible for the failure rates
leading to a significantly reduced availability on demand of the equipment (MIL
1960).

In February 1963 the first symposium on advanced marine engineering concepts for
increased reliability was held at the office of Naval Research at the University of
Michigan. In December 1963 a paper entitled “Reliability Engineering Applied to the
Marine Industry” was presented at the Society of Naval Architects and Marine
Engineers (SNAME) and the following year in June another paper, entitled
“Reliability in Shipbuilding”, was presented. Following the presentation of these two
papers, SNAME in 1965 established Panel M-22 to investigate the new discipline as
applied to marine machinery and make it of use to the commercial marine industry.

In the last three decades, stimulated by public reaction and health and safety
legislation, the use of risk and reliability assessment methods has spread from the
higher risk industries to an even wider range of applications. The Reactor Safety
Study undertaken by the U.S.A. (U.S Nuclear Regulatory Commission (1975) ) and
the Canvey studies performed by the UK Health & Safety Executive resulted from a
desire to demonstrate safety to a doubtful public. Both these studies made
considerable use of quantitative methods, for assessing the likelihood of failures and
for determining consequence models.

2
There is a long history in the United Kingdom (UK) on research, development and
successful practical application of safety and reliability technology. There is a
continuing programme of fundamental research in areas such as software reliability
and human error in addition to further development of the general methodology.
Much of the development work was carried out by the nuclear industry. Based on the
considerable expertise gained in the assessment of nuclear plants, a National Centre
for System Reliability (NCSR) was established by the UK Atomic Energy Authority
(UKAEA) to promote the use of reliability technology. This organization plays a
leading role in research, training, consultancy and data collection. The NCSR is part
of the safety and reliability directorate of the UKAEA, which has played a major role
in formulating legislation on major hazards, and has carried out major safety studies
on industrial plants. It is noted that some of the major hazard studies commissioned
at the national level in the UK have included the evaluation of the risks involved as a
result of marine transportation of hazardous materials such as liquefied gases and
radioactive substances. It is expected that the recent legislation in relation to the
control of major hazards will result in a wider use of quantitative safety assessment
methods and this will inevitably involve the marine industry.

Most chemical and petrochemical companies in the UK have made use of safety and
reliability assessment techniques for plant evaluation and planning. Similar methods
are regularly employed in relation to offshore production and exploration
installations.

The Royal Navy has introduced reliability and maintainability engineering concepts
in order to ensure that modern warships are capable of a high combat availability at
optimum cost. The application of these methods has been progressively extended
from consideration of the operational phase and maintenance planning to the design
phase. To date, comparatively little use of safety and reliability assessment methods
has been made in connection with merchant shipping. Lloyd’s Register of Shipping
has for a long period, collected information relating to failures and has carried out
development work to investigate the application of such methods to the classification
of ships. Apart from this, some consultancy work has also been carried out on behalf
of ship owners. One example is the P&O Grand Princess , for which a
comprehensive safety and availability assurance study was carried out at the concept
design stage of this cruise ship (Best and Davies, 1999). Established risk assessment

3
techniques were used including Failure Mode and Effects Analysis (FMEA),
flooding risk analysis and fire risk analysis. The resultant ship was believed to be
better and safer than it would have been otherwise. P&O has now developed an in-
house safety management system which is designed to capture any operational
feedback, so as to improve the safety and efficiency of its cruise fleet operation and
to use it for better design in the future. The merchant ship-building yards in the UK,
having seen the success of the warship yards in applying Availability, Reliability and
Maintainability (ARM) studies at the design stage, are actively seeking benefits from
adopting a similar approach. Some joint industry-university research projects are
being undertaken to explore this area (Molland, 2008).

1.3 Applications of RAM Analysis

Reliability Availability and Maintainability (RAM) analysis is established at first by

NASA and US Air Force, and later improved especially by household appliance
producers in order to decrease the costs paid by themselves during the warranty
period of the product.

NASA has established this approach to reduce the chance of failure which may occur
during the space program, since failures could not be repaired after launch of the
space crafts. That’s why, to achieve minimum number of faults during space craft
production has been very important for NASA. US Air Force followed NASA in
RAM analysis applications.

Especially in flight operations, some failures cause fatal consequences which makes
the reliability highly important. As in space programs of NASA, US Air Force
started to apply reliability programs particularly for electronic equipments. The aim
was to decrease the failure rate of electronic devices. Reliability programs held by
US air Force motivated US Department of Defence (DoD) to indicate some standards
for reliability programs. MIL-STD-721C Definition of Terms for Reliability and
Maintainability is one of the sources stating the definitions about RAM Analysis.
Another source printed by DoD about RAM Analysis is MIL-STD-756B Reliability
Modelling and Prediction including the information on modelling and predicting the
reliability of a system. DoD has established lots of standards on reliability by
publishing handbooks and directives.

4
After the success gained by RAM Analysis in military area, RAM analysis was used
by commercial purposes. Producers needed to improve the reliability of their items in
order to seize the confidence of customers. Extended warranty periods are preferred
by end user when two items to be bought were compared. Since extending the
warranty period would increase the after-sales services costs, producers thought that
it would be more economical to produce reliable items, instead of losing more money
in repairs. Producers aimed to serve their products in their useful life in which less
number of failures occur. Figure 1.1 shows bathtube curve including three phase of
product life. First phase is initial period through which fabric tests are applied to
products. In the initial period number of failures is high. Producers aim to deliver the
products to costumers after this period. Second phase is useful life of the product in
which number of failures is less than initial period and wear-out period. During this
period failure rate (λ) is constant.

Figure 1.1 : Bathtube curve.

Currently most of the companies prepare reliability programmes to perform RAM

Analysis in design phase. According to the results obtained from RAM Analysis,
producers make necessary changes on project or product to increase the reliability.
Making alterations in design phase decreases the expenditures of the company for the
faults of the product which will be experienced after-sale phase. Repairs or

5
corrections after the product sold also cause bad reputation for the product and
company.

Because of the reasons explained above, RAM Analysis has gained well-deserved
importance in almost every engineering area. Reliability prediction has been made
for repairable and non-repairable items currently. For non-repairable and repairable
items, reliability analysis has been made respectively on the basis of Mean Time To
Failure (MTTF) and Mean Time Between Failures (MTBF). For both types the aim
targeted is to decrease the number of failures and increase MTTF or MTBF
especially in warranty period of the product. Increasing the reliability of the products
by programs hold has given producers an opportunity to extend the warranty periods.
Thanks to the extended warranty periods, producer have got advantage in
competition against the rivals. Products with extended warranty periods have been
chosen by the customers, since these products made people think that they were more
reliable than before. Producers also have got cuts in expenditures in warranty period
which is determined according to the first phase of bath-tube curve for failures. RAM
Analysis has shortened the first part of the curve through which more failures
occurred compared with the latest life cycle of the product. Hence, producer still
believe the benefits of RAM Analysis and commonly use reliability programmes in
design periods.

Since increasing concern and need for RAM Analysis in industrial area, reliability
has found a place in engineering education as lectures on different engineering
programmes. Some international meetings, conferences and trainings have been held
about reliability and still continue. Some software have been prepared and provided
commercially in order to make reliability calculation of the complex systems.

A marine application of RAM Analysis is “Study of Reliability, Maintainability and

Availability: A Case Study of a Shuttle Tanker ropulsion System” by
Balingwi.(1999). In this research, ship propulsion system is modelled in order
topredict and optimize the effectiveness of the ship propulsion system. The
objectives of this research were to review the process of evaluatinga shuttle tanker
propulsion system’s reliability, maintainability and availability, and to investigate the
computurised simulation statistical approach to help manage the information which
is required in making intelligent maintenance and repair decisions.

6
2. DEFINITIONS

2.1 Reliability

Reliability may be expressed as: “The probability that an item will perform required
function without failure under a stated condition for a stated period of time”
(O’Connor, 1981). A customer, purchasing the product, accepts that it may fail at
some future time. Coupling this acceptation with a warranty period relieves the
customer about the failures of the item in future. But this relief does not last after
warranty period. During the warranty period problems are solved by producer
without any charge. It seems that failures occurred during warranty period are not
problem for both side, customer and producer. In fact it is not so. Increase in number
of failures causes warranty costs for the producer increase, as it is inconvenient for
the customer also. Outside the warranty period, only customer suffers about the
failures. In both cases, producer will probably incur a loss of reputation which may
affect future business relations.

Reliability may also be expressed in other ways. One of the definition states that
“reliability for non-redundant items is the duration or probability of failure-free
performance under stated conditions. For redundant items it may be expressed as the
probability that an item can perform its intended function for a specified interval
under stated conditions” (MIL-STD 721C).

2.2 Maintainability

Maintainability is an expression about repairable items. Non-repairable items are the

ones used just for once and disposed i.e. fuel filters. Systems are repaired when they
fail, and some labour force is spent for the system to work properly. These all efforts
are fulfilled to maintain the system. How easy the system can be carried out by repair
and other maintenance work shows the maintainability of the system.

7
Maintainability can be quantified as the mean time to repair (MTTR). The time
needed for repair including several activities may be divided into three groups as
below (O’Connor, 1981);

1. Preparation time which consist of finding person for the job, travel,obtaining
tools and test equipment,

2. Active maintenance time at which job is actually done,

3. Delay time caused by waiting for the spare parts etc after the job has already
been started.

Maintainability is expressed as “the measure of the ability of an item to be retained in

or restored to specified condition when maintenance is performed by personnel
having specified skill levels, using prescribed procedures and resources, at each
prescribed level of maintenance and repair” (MIL-STD 721C).

Maintained systems may be subject to corrective and preventive maintenance.

Corrective maintenance includes all actions to return a system from a failed to an
operating or available state. The amount of corrective maintenance is therefore
determined by reliability. Corrective maintenance action cannot be planned. It may
be needed even when it is not expected. The aim of preventive maintenance is to
retain the system in an operational or available state. This aim may be achieved by
preventing the failures before they happen. In a mechanical system it may be
possible by the ways of lubrication, cleaning, inspection and calibration which are
made in schedule. Preventive maintenance affects reliability of a system directly.

2.3 Availability

According to military standards of US Department of Defence, availability is

described as; “a measure of the degree to which an item is an operable comitable
state at the start of a mission when the mission is called at unknown (random) time
(MIL-STD 721C). It is needed to explain the difference between availability and
dependability. Availability concerns the time before the mission starts. If system is
ready to perform the mission when it is ordered, then availability of the system is
mentioned. But, if we talk about the system’s ability to continue its performance
during the mission, then we emphasize dependability of the system.

8
The time taken to repair the failures and to carry out the preventive maintenance
removes the system from the available state. There is thus a close relationship
between reliability and maintainability , one affecting the other and both affecting
availability and costs. Assuming that maintenance actions occur at a constant rate, in
a steady state after a transient behavior has settled down availability may be
formulated as below (O’Connor, 1981);

2.4 Redundancy

The existence of more than one means to accomplishing a given mission is called as
redundancy. In naval ships redundancy has high importance to increase the
availability of a system without any interruption.

2.5 Mean Time Between Failures (MTBF)

MTBF is described as the mean number of life units during which all parts of item
perform in their specified limits, during a particular time interval under stated
conditions. MTBF is a basic measure of reliability for repairable items.

2.6 Mean Time To Failure (MTTF)

MTTF is the mean number of life units of an item divided by the total number of
failures within that population during a particular measurement interval in stated
conditions. MTTF is a basic measure of reliability for non-repairable items.

2.7 Mean Time To Repair (MTTR)

The sum of corrective maintenance times at any maintenance level of repair divided
by the total number of failures within an item repaired at that level during a particular
interval in stated conditions. MTTR is a basic measure of maintainability.

9
10
3. RELIABILITY

In the broadest sense, reliability is associated with dependability, with successful

operation, and with the absence of breakdowns or failures. It is necessary for
engineering analysis, however, it is about defining reliability quantitatively as a
probability. Thus reliability is defined as the probability that a system will perform
its intended function for a specified period of time under a given set of conditions.

A product or system is said to fail when it ceases to perform its intended mission.
This cessation may occur as entirely breakdown or as lower performance for the
mission intended. A generator may not produce electricity because of the absence of
exciting current. This type of failure may be referred as complete breakdown of the
generator. But if it produces energy lower than it is intended, it has lower
performance. This may be caused by a failure on fuel supply system of the engine.
In both case generator does not perform well. It is necessary to define failure
quantitatively in order to take into account the more subtle forms of failure. Having
knowledge of why the failure occurred in detail would help to calculate the reliability
of the system more accurately.

The expression of time in the definition of reliability may vary in some cases. When
we consider a intermittently working device can we talk about calender time? If the
operation is cyclic, such a on-off of a switch, time is likely to be cast in terms of
number of the operations. If we consider a pump working intermittently, we should
cast the time in terms of hours of operation. If we use calender time in calculations,
then we must consider the frequency of starts and stops and the ratio of operating to
total time. Instead of calender time, it seems better to use operating hours for the best
practice.

3.1 Reliability Mathematics

Reliability concerns the probability of a device to have failure in a specific time

period. Reliability can be specified as the mean number of failures in a given time
which can be also described as failure rate or can be expressed as the mean time

11
between failures MTBF for repairable items, or as the mean time to failure MTTF for
non-repairable items. Repairable items are repaired and returned to use again after
repair. For repairable items, it is usually assumed that failures occur at constant rate,
and it is expressed as (O’Connor, 1981);

(3.1)

3.2 Redundancy

Redundancy has great importance in naval ships. All naval ship are designed in
capability to serve continuously even when some devices have faults which prevent
the device performing the mission properly. In order to provide uninterrupted
mission accomplishment, main devices have standby systems which will work in
case of failure of actual one. Thus, system performance is kept in any case of system
failure.

3.3 System Structures

It is generally excepted that there are four generic types of relationships between a
device and its components. These relationships may be expressed as series, parallel,
k out of n and others. These relationships directly affect the redundancy of the
system.

3.3.1 Series systems

The simplest and most commonly encountered configuration of components is the

series system. “A series system is one in which all components must function
properly in order for the system to function properly” (Nachlas, 2005). According to
the definition, if one of the components fails, then system cannot perform the
properly. Reliability block diagram for a series system may be shown as in Figure
3.1.

1 2 3

Figure 3.1 : Series system.

The function of system may be expressed as;

12
 ( ) ∏ (3.2)

Only the functioning of all components yields system function.

3.3.2 Parallel system

The second type of components’ structure is the parallel structure. “A parallel system
is one in which the proper function of any component implies system function”
(Nachlas, 2005). One example of a parallel system is the set of two engines on a two
engine electric supply system of a ship. As long as at least one of the engine function
properly, supplement of electricity through the ship may be accomplished. The
function for parallel system is;

( ) ∐ ∏ ( ) (3.3)

The structure function for a parallel system may be expressed as Figure 3.2;

Figure 3.2 : Parallel system.

Conceptually a parallel system is failed when all system components are failed.
Parallel arrangement of components is often referred to as redundancy. This is
because the proper function of any of the parallel components implies proper
function of the structure. Thus, the additional components are redundant until an
actually performing component fails. Frequently, parallel structures are included in
product designs specifically because of resulting redundancy. Often but not always,
the parallel components are identical. At the same time, there are actually several
ways in which the redundancy may be implemented. A distinction is made between

13
redundancy obtained using a parallel structure in which all components function
simultaneously and that obtained using parallel components of which one functions
and the others wait as standby units until the failure of functioning unit.

3.3.3 K-out-of-n systems

“A k-out-of-n system is one in which the proper function of any k of the n

components that comprise the system implies proper system function” (Nachlas,
2005). In this type of structures, the number of components needed to imply the
function properly is indicated by letter k, while system has more number of similar
components which is indicated by letter n.

Electric supply system of a large ship may be described by this type of structure. In
large naval ships for example in frigates, there several number of generators to for
electric supply. These generators placed in different parts of the ship may be
designed to supply different networks or all may supply all the networks. In naval
ships generators are designed to a power more than the ship needs. Even in a small
naval boat such as coast guard boats, there are at least two generators for electric
supply, even though one is enough. In large ships having 5 generators, 3 of them are
on and it is enough to function the electric system. It has no importance which of the
5 generators are on.

The function for a k-out-of-n system;

∑
( ) { (3.4)

3.4 Failure rate

The failure rate which is donated by λ, is expressed in terms of failures per unit time,
such as failures per hour or failures per 100 hours or failures per 1000 hours. It is
computed as a simple ratio of the number of failures, f, during a specified test
interval T;

(3.5)

14
3.5 Mean time between failures (MTBF)

During the operating period, when failure rate is fairly constant, MTBF is reciprocal
of the constant failure rate to the number of failures (Govil, 1983)

(3.6)

3.6 Mean time to failure (MTTF)

For an information on n items with failures t1,t2,.....tn, MTTF is defined as;

∑ (3.7)

3.7 Mean time to repair (MTTR)

For an information on n items with repair times t1,t2,.....tn, MTTR is defined as;

∑ (3.8)

3.8 Reliability

The constant failure rate model for continously operating systems leads to an
exponential distribution (Lewis, 1996). Probability density function for a constant
failure rate (PDF);

( ) (3.9)

Similarly, cumulative distribution function (CDF) becomes

( ) (3.10)

And reliability may be written as

() (3.11)

15
16
4. FAULT TREE ANALYSIS (FTA)

Fault Tree Analysis (FTA) is a formal deductive procedure for determining

combinations of component failures and human errors that could result in the
occurrence of specified undesired events at the system level (Ang and Tang ,1984).

It is a diagrammatic method used to evaluate the probability of an accident resulting

from sequences and combinations of faults and failure events. This method can be
used to analyse the vast majority of industrial system reliability problems. FTA is
based on the idea that:

1. A failure in a system can trigger other consequent failures.

2. A problem might be traced backwards to its root causes.

3. The identified failures can be arranged in a tree structure in such a

way that their relationships can be characterised and evaluated
(Andrews and Moss, 2002).

4.1 Benefits To Be Gained From FTA

There are several benefi ts of employing FTA for use as a safety assessment tool.
These include:

1. The Fault Tree (FT) construction focuses the attention of the analyst
on one particular undesired system failure mode, which is usually
identified as the most critical with respect to the desired function.

2. The FT diagram can be used to help communicate the results of the

analysis to peers, supervisors and subordinates. It is particularly useful
in multi-disciplinary teams with the numerical performance measures.

3. Qualitative analysis often reveals the most important system features.

4. Using component failure data, the FT can be quantified.

17
 5. The qualitative and quantitative results together provide the decision-
maker with an objective means of measuring the adequacy of the
system design.

An FT describes an accident model, which interprets the relation between

malfunction of components and observed symptoms. Thus the FT is useful for
understanding logically the mode of occurrence of an accident. Furthermore, given
the failure probabilities of the corresponding components, the probability of a top
event occurring can be calculated. A typical FTA consists of the following steps:

1. System description.

2. Fault tree construction.

3. Qualitative analysis.

4. Quantitative analysis.

These steps are illustrated in Figure 4.1 .

System description

Qualitative
Fault tree construction analysis

Quantitative
analysis

Figure 4.1 : FTA Construction Steps.

4.2 System Definition

FTA begins with the statement of an undesired event, that is, failed state of a system.
To perform a meaningful analysis, the following three basic types of system
information are usually needed:

1. Component operating characteristics and failure modes: A description

of how the output states of each component are infl uenced by the
input states and internal operational modes of the component.

18
 2. System chart: A description of how the components are
interconnected. A functional layout diagram of the system must show
all functional interconnections of the components.

3. System boundary conditions: These define the situation for which the
fault tree is to be drawn.

4.3 Fault Tree Construction

FT construction, which is the first step for a failure analysis of a technical system, is
generally a complicated and time-consuming task. An FT is a logical diagram
constructed by deductively developing a specific system failure, through branching
intermediate fault events until a primary event is reached. Two categories of graphic
symbols are used in an FT construction, logic symbols and event symbols.

The logic symbols or logic gates are necessary to interconnect the events. The most
frequently used logic gates in the fault tree are AND and OR gates. The AND gate
produces an output if all input events occur simultaneously. The OR gate yields
output events if one or more of the input events are present. The event symbols are
rectangle, circle, diamond and triangle. The rectangle represents a fault output event,

which results from combination of basic faults, and/or intermediate events acting
through the logic gates.

The circle is used to designate a primary or basic fault event. The diamond describes
fault inputs that are not a basic event but considered as a basic fault input since the
cause of the fault has not been further developed due to lack of information. The
triangle is not strictly an event symbol but traditionally classified as such to indicate
a transfer from one part of an FT to another. Figure 4.2 gives an example of a fault
tree.

To complete the construction of a fault tree for a complicated system, it is necessary

first to understand how the system works. This can be achieved by studying the blue
prints of the system (which will reflect the interconnections of components within
the system). In practice, all basic events are taken to be statistically independent
unless they are common cause failures. Construction of an FT is very susceptible to
the subjectivity of the analyst. Some analysts may perceive the logical relationships
between the top event and the basic events of a system differently. Therefore, once

19
the construction of the tree has been completed, it should be reviewed for accuracy,
completeness and checked for omission and oversight. This validation process is
essential to produce a more useful FT by which system weakness and strength can be
identified.

Figure 4.2 : FTA Example.

4.4 Qualitative Fault Tree Evaluation

Qualitative FTA consists of determining the minimal cut sets and common cause
failures. The qualitative analysis reduces the FT to a logically equivalent form, by
using the Boolean algebra, in terms of the specific combination of basic events
sufficient for the desired top event to occur. In this case, each combination would be
a critical set for the undesired event. The relevance of these sets must be carefully
weighted and major emphasis placed on those of greatest significance.

4.5 Quantitative Fault Tree Evaluation

In an FT containing independent basic events, which appear only once in the tree
structure, then the top event probability can be obtained by working the basic event
probabilities up through the tree.

In doing so, the intermediate gate event probabilities are calculated starting at the
base of the tree and working upwards until the top event probability is obtained.

20
When trees with repeated events are to be analysed, this method is not appropriate
since intermediate gate events will no longer occur independently. If this method is
used, it is entirely dependent upon the tree structure whether an overestimate or an
underestimate of the top event probability is obtained. Hence, it is better to use the
minimal cut-set method.

The occurrence probability of a top event can then be obtained from the associated
minimum cut sets. The following two mini-trees are used to demonstrate how the
occurrence probability of a top event can be obtained:

Figure 4.3 : Minimum Cut Set 1.

Obviously the minimum cut set for the mini-tree below is A · B .

If one event is independent from the other, the occurrence probability of top event Z:

( ) ( ) ( ) ( ) (4.1)

where P(A) and P(B) are the occurrence probabilities of events A and B.

Figure 4.4 : Minimum Cut Set 2

21
Obviously the minimum cut set for the mini-tree above is A + B.

If one event is independent from the other, the occurrence probability of top event Z
is

( ) ( ) ( ) ( ) ( ) ( ) (4.2)

where P(A) and P(B) are the occurrence probabilities of events A and B.

FTA may be carried out in the hazard identification and risk estimation phases of the
safety assessment of ships to identify the causes associated with serious system
failure events and to assess the occurrence likelihood of them. It is worth noting that
in situations where there is a lack of the data available, the conventional FTA method
may not be well suited for such an application.

22
5. SCOPE OF THE THESIS

Through this thesis, reliabilities of the main systems, which are crucial for the
mission of the ship, have been analyzed. Firstly, the main systems required to
accomplish the mission of the ship are determined. Systems are chosen so that even
if one of the systems is failed, ship cannot perform the mission. Failure data are
needed to compute reliability of the ship. They have been collected from 5 sister
ships of Turkish Navy (TN). These ships are at service as auxiliary ships.

Data have been collected from 5 ships for the period between two overhaul periods
of the ships. Data from all ships are analyzed and the one which has highest number
of failures is chosen for the project. Events are chosen from different ships and a
virtual ship is determined with the events which are the highest among others. In this
way the results compiled by the project will be the worst case for the ship class.

The systems chosen for an auxiliary ship are propulsion system, steering gear
system, damage control system and electric supply system, shown in Figure 5.1.
These systems have been branched to subsystems and components. Each
component’s number of failures’ data has been used to compute failure rate of the
components. Failure rates, MTTF, MTTR and MTBF have been computed on a MS
Excel sheet. It is assumed that components have constant failure rates and reliability
values are computed according to exponential distribution as shown Equation 3.11.

Figure 5.1 : Ship SystemRBD.

Failure rate and MTBF data have been imported to Isograph Reliability Workbench
11.0. By using the software RBDs for each system including all components, have
been prepared. MTTF and MTTR values of the components have been imported to
the software and unavailability and unreliability values of the system have been
computed.

23
After preparing RBDs for the ship’s systems, fault tree (FT) construction has been
produced by the software. Since FT produced by software is complicated and hard to
follow, simplified FT of the systems are prepared manually.

5.1 Assumptions

Through the thesis, five of an auxiliary class of Turkish Navy Ships have been
examined. Failure reports of five ships have been collected. The mostly experienced
failures in all ships have been examined and the one which has highest failure rate
among identical components has been chosen for analysis. For all the systems
working hour has been identified as the time between two overhaul period, which is
being executed as 6 years for the class of ships in Turkish Navy.

For the systems and components serving as auxiliary apparatus e.g. fuel transfer
pump, fire-figthing pump, hatches, portholes etc., six years of maintenance period,
which is equal to 52560 hours has been identified as working hours.

For propulsion units, number of failures have been collected in all ships and it
assumed that five ships’ propulsion systems are identical. The number of working
hours of chosen component has been taken into account. The working hour is
recalculated directly proportional to ship’s overhaul period 6 years, 52560 hours in
order to use the same project time for all the ship systems.

For electric production generators No:1 and No:2 of all ships have been examined
and in order to represent the worst case, highest number of failures of the
componenets have been chosen as in propulsion system.

For Steering Gear System working hours of the components have been taken
according to the number of working hours of the propulsion components, since
Steering Gear would have the same working hours with propulsion system.

5.2 Utilization of Isograph Reliability Workbench 11.0.

Isograph Reliability Workbench is a windows based commercial software capable of

reliability production. First step in software is preparing reliability block diagram.
Blocks for each component must be prepared and linked according to the system
construction. For this thesis, values which should be filled in are MTTF and MTTR
for each event. After linking the components and filling the MTTF and MTTR

24
values, software computes the unavailability of the components and systems to
compute total unavailability of the project (Isograph, 2011).

The Reliability Block Diagram (RBD) module allows the user to build an RBD to
represent the system to be modelled. The blocks in the diagram represent sub
systems, components and events that can occur in the system. The logic of the
system is dictated by the way in which the blocks are connected together.

Once the RBD is constructed, the diagram may be populated with failure and repair
information. Analysis of the system returns estimates of system parameters, minimal
cut set data and importance information for highlighting critical areas of the system.

Before building an RBD it is first necessary to create a System. A System represents

the highest level of the system to be modelled. Once created, the new System will
appear in the Tree Control under the RBD Pages node. The user may then select the
System in the Tree Control and add RBD structure in the diagram area.

In the RBD, blocks represent sub systems, components and events. Each block can
have failure and repair data associated with it. The arrangements in which the blocks
are connected determine the logic of the system and thus affect the minimal cut sets
and system parameters. An example of RBD shown in Figure 5.2.

Nodes may be used to commence and terminate parallel RBD arrangements, and to
manipulate the behaviour of those arrangements. For example, in a voted
arrangement the vote number is applied at the output node. Nodes may also be used
to alter the shape of connections on screen.

Figure 5.2 : RBD construction example.

25
A large RBD can become difficult to view and to navigate. Hence, as an RBD gets
larger it may become necessary to break it down into more manageable pieces.
Furthermore, the user may wish to view results for different sub systems, as well as
for the system as a whole. Both of these goals can be achieved using the sub system
facility of the RBD module.

In order to determine system parameters such as unavailability and failure frequency

the user must allocate failure and repair data to the component blocks in the RBD.
This is done via the Generic Failure Models. A Generic Failure Model may be
created containing failure and repair information. Screenshot of Generic Failure
Model input box is shown in Figure 5.3. It may then be allocated to one or more
blocks in the RBD. Blocks which use the same Generic Model will share the same
failure data but will remain independent of one another. List of the generic failure
models generated for this project is illustrated in Appendix A.

Figure 5.3 : Failure model window.

Before analyzing the project, the user must first make sure that the system lifetime is
set correctly. For this thesis, life-time is assigned as 6 years meaning 52560 hours
and actual working hours of main engines 2500/2550 hours and of generators
3260/3270 hours are projected to 6 years life-time.

The Fault Tree module allows the user to build a fault tree to represent the system to
be modelled. An example of FT is shown in Figure 5.4. A fault tree consists of logic

26
gates representing systems and sub systems, and basic events at the roots of the tree
representing component failures and events. The type of logic gates selected dictate
the way in which the failures interact.

Figure 5.4 : Faul tree example.

Failure mode, unavaliability values may be shown under blocks after completing the
analysis. Results may be exported by various reports. Some reports generated by
Isograph Reliability Workbench 11.0.are shown in Appendices A-I.

5.3 Isograph Reliability Workbench 11.0. Calculations

5.3.1 Unavailability of a component (Q) and component failure frequency (ω)

To calculate the unavailability of a component, software needs inputs of failure rate

(λ), MTTF and MTTR values, which are both calculated on a MS Excel sheet.
Failure rate (λ) is defined as;

(5.1)

27
The unavailability of a component (Q) is calculated by the software as;

() (5.2)

Failure frequency of the component is;

() ( ( )) (5.3)

5.3.2 Unavailability of a sub-system and system (Qsys)

The structure of a reliability block diagram (RBD) defines the logical interaction of
failures within a system. Individual blocks may represent single component failures,
sub-system failures and other events that may contribute towards system failures.
The reliability behavior of an individual sub-system block may be represented by a
RBD at a lower hierarchical level.

For the system to be successful in its operation, at least one path must be maintained
between the system input and output nodes. A simple series arrangement of 3 blocks
A, B and C would only require one of the blocks to fail to eliminate the single
success path from input to output node. Simple series arrangement of a system is
shown on Figure 5.5.

Figure 5.5 : Simple series arrangement.

System unavailability of a serially connected components is calculated as,

∑ (5.4)

For the example series arrangement above, System unavailability is,

(5.5)

A simple parallel arrangement of 3 blocks A, B and C would require all 3 blocks to

fail to eliminate the 3 success paths from input to output node.

28
 Figure 5.6 : Simple parallel arrangement.

Figure 5.6 shows a simple parallel arrangement of components. System

unavailability of a parallel connected components is calculated by;

∏ (5.6)

For the sysytem shown on Figure 5.5, system unavailability;

(5.7)

Since only one path is enough for the success of the system, if one of the
componenets’ unavailability equals to zero, then system unavailability becomes zero.
Total ship unavailabilty is calculated by Equations (5.5) and (5.7) according to the
systems’ types of arrangement.

5.3.3 Cut sets occurance probability (Qcut)

The RBD Module uses efficient minimal cut sets generation algorithms to analyze
large and complex RBDs. Cut sets represent a minimal combination of failures which
will cause the system to fail. Table of the cut sets generated by software, which are
affecting system unavailability, is illustrated on Appendix B.

Cut set occurance probability may be expressed as,

∏ (5.8)

where Qi is the unavailability of the ith event in the cut set.

Failure frequency of the cut set may be expressed as,

∑ ∏ (5.9)

29
30
6. TOTAL SHIP RELIABILITY ANALYSIS

RWB software analyzes the system and, unavailability and unreliability results of the
components and systems are computed by RWB. A block in RBD represents an
event of a component or a system which has more than one component’s events.
Serial or parallel arrangement of components determines how the calculations are
carried out. Sub-system results are computed through components contributing
system unavailability. At the end, for this project, a total ship unavailability result is
calculated by the software. The list of the events contributing to ship unavailability
and prepared as blocks in RBD are listed with generic failure types in Appendix C.
Those blocks which have no generic failure data represent a sub-system or system in
RBD and they do not need generic failure data input, since components’ generic
failure data are used in calculation.

6.1 MTTF-MTTR Calculations

According to the model type chosen for the project, RWB needs some inputs for the
calculation. For this project, MTTF model type has been chosen and necessary inputs
are MTTF and MTTR values. The MTTF and MTTR values have been calculated on
MS Excel Worksheet and shown in Appendix D. These values have been imported to
RWB via Generic Failure Models.

Data used to calculate MTTF and MTTR are listed on event basis in Appendix E and
Appendix F respectively.

In order to calculate MTTF and MTTR values, data from ships’ log books have been
used. MTTF and MTTR have been calculated by the Equations (3.7) and (3.8)
respectively on a MS Excel worksheet.

6.2 Unavailability Calculations

RWB makes unavailability calculations for the system, sub-systems and components
acccording to the values inserted into events’ generic failure models. Before starting
the analysis, RBD should be prepared.

31
RBD has been constructed according to the effects of the events about the
accomplishment of the ship’s mission. After constructing the RBD, generic failure
models were prepared and attached to the relevant events. Software analayzed the
system and unavailabilities have been computed. RBDs with unavailability results
for the system, sub-systems and events are shown in Appendix G.

RWB has calculated unavailabilities of the events according to the Eqs. (5.1) and
(5.2). Unavailabilities of the sub-systems and system have been calculated by RWB
according to the Eqs. (5.4) and (5.6).

In order to find unavailability of a serially arranged system or sub-system,

unavailabilities of the events or sub-systems composing the relevant sub-system or
system are summed. To find unavailability of a sub-system or system constructed in
parallel, unavailabilities of the events or sub-systems are multiplied. Hence, in a
parallel arrangement, if one of the events has unavailability value as zero, then
mission can be accomplished and unavailability of the sub-system or system equals
to zero.

6.3 Results and Discussion

RWB calculates system unavailability and this result may show how reliable the
system is. RWB reports unavailability, failure frequency and unreliability of each
RBD blocks. This report is shown in Appendix H.

Unavailability of the sub-system is a function of MTBF, MTTR and preventive

maintenance. In this project, preventive maintenance time is neglected.
Unavailability and failure frequency of a sub-system are constant. Since reliability of
the system is the function of failure rate (λ) and time as indicated at Equation (3.11),
RWB calculates system and sub-systems’ unreliabilities in 20 working hour steps. As
shown in Appendix H, unreliability value of the sub-systems are increasing
proportionally with working hours. Unreliability of the system (Fsys) is calculated by
the software as;

∫ ( )
(6.1)

Where λsys is system failure rate and calculated as;

(6.2)

32
Where ωsys is system failure frequency and calculated as;

∑ (6.3)

Reliability values may be calculated by Eq. (6.4);

(6.4)

RWB also calculates total down time (TDTsys) and number of expected failures
(Wsys) by the Eqs. (6.5) and (6.6) respectively.

∫ ( ) (6.5)

∫ ( ) (6.6)

6.3.1 Unavailability of main sub-systems

Four main sub-system have been constructed for the ship type examined. These sub-
systems are serially arranged and directly affect the availability of the ship.
Unavailability diagram of main sub-systems is shown in Figure 6.1.

Figure 6.1 : Unavailability of main sub-systems.

Since unavailability is a function of failure rate (λ) and MTTR, it does not change
with working hour. System unavailability is computed through the unavailabilities of
the cut sets by cross-product method in RWB as;

33
 () ∑ () ∑ ∑ () ∑ ∑ ∑ () (6.5)

Ship total unavailability may be calculated also by summation of main sub-systems’

unavailabilities. Sub-system Damage Control contribution is higher than other
systems, since the unavailability of portholes increases the unavailability of water-
tight compartments. Total ship system’s unavailability was calculated by RWB as
Q=0,0003726. The availability of the system and sub-systems may be calculated by;

(6.6)

The availability of total ship system then becomes 0,996274. This availability value
is very high and shows that, during the project time, the ship is highly capable of
accomplishing the mission.

6.3.2 Number of expected failures of main sub-systems

Number of expected failures of the sub-systems are calculated by RWB and shown in
Figure 6.2. Damage Control system has highest number of expected number of
failures.

Figure 6.2 : Number of expected failures of main sub-systems.

6.3.3 Unreliability of main sub-systems

Unreliabilities of system and sub-systems are calculated and plots are prepared by
RWB, as shown in Figure 6.3 and Figure 6.4 respectively. It is observed from these

34
figures that, unreliabilities of the system and sub-systems are increasing with
working hour, since reliability is an exponential function of failure rate (λ) and time.

Since failure rate (λ) is constant for the project time, 52560 hours, working hour of
the system increases the unreliability of the system. Reliability of a component can
be calculated by Eq. (3.11) and by the unreliability results of RWB.

It is usual that reliability of the system decreases towards the end of the project time.
When Figure 6.4 examined, it is obvious that, Damage Control main sub-system has
the most contribution to low reliability value of the system. Contributions of the
main sub-systems via their sub-systems are examined below in detail.

Block Time Profile

SHIP
1 UNAVAILABILIT
Y

0,9

0,8

0,7

0,6
Unreliability

0,5

0,4

0,3

0,2

0,1

0
0 5256 10512 15768 21024 26280 31536 36792 42048 47304 52560

Time

Figure 6.3 : Unreliability of system.

6.3.3.1 Contribution of propulsion sub-system

Propulsion system is composed of two main diesel engines including events and sub-
systems. RWB result summary of propulsion system is shown on Table 6.1. As
shown on Table 6.1, Total Down Time (TDT) of propulsion system, which is
consisted of Main Engine No:1 and Main Engine No:2, is 0,202 hours through
project time 52560 hours. This low value is due to the parallel arrangement of main
engines in propulsion system RBD. Only one of the engines is accepted as sufficient
in order to accomplish the mission of the ship.

35
 Block Time Profile
PROPULSION
1 SYSTEM

STEERING
GEAR
0,9
ELECTRIC
POWER
SYSTEM
0,8
DAMAGE
CONTROL
SYSTEM
0,7

0,6
Unreliability

0,5

0,4

0,3

0,2

0,1

0
0 5256 10512 15768 21024 26280 31536 36792 42048 47304 52560

Time

Figure 6.4 : Unreliabilities of main sub-systems.

When Table 6.1 is examined, it is seen that, unreliabilities of each engine are
calculated as 1. But RWB calculated propulsion system’s unreliability as 0,1305,
since RWB uses cut sets’ unreliabilities and unavailabilities to calculate system’s
unreliability and unavailability. Cut sets used in calculation are illustrated in
Appendix B. These cut sets are generated by software according to their effects on
sub-system’s success.

Table 6.1 : Propulsion system result summary.

No.of
Unavailability Unreliability Expected TDT MTTF MTTR
Failures
Propulsion
3,87E-06 0,1305 0,1398 0,202 3,74E+05 1,448
System
Main Eng.
0,002248 1 31.93 117,6 1641 3,701
No:1
Main Eng.
0,00172 1 37,93 89,94 1383 2,383
No:2

36
 Figure 6.5 : Main Engine No:1 unavailability diagram.

Contributions of sub-systems to Main Engines’ unavailabilities are shown in Figures

6.5 and 6.6 Unavailabilities of the sub-systems are constant since failure rate does
not change with time.

Figure 6.6 : Main Engine No:2 unavailability diagram.

37
 Block Time Profile

1 MAIN ENG1

MAIN ENG
FUEL
0,9 SYSTEM1

MAIN ENG
LUBOIL SYS1
0,8 MAIN ENG
COOLING
WATER1
0,7 MAIN ENG LUB
OIL TEMP1

MAIN ENG
0,6 CHARGE AIR
Unreliability

SYSTEM1
MAIN ENG
0,5 START SYS1
MAIN ENG SEA
WATER1
0,4

0,3

0,2

0,1

0
0 5256 10512 15768 21024 26280 31536 36792 42048 47304 52560

Time

Figure 6.7 : Main Engine No:1 unreliability-time diagram.

Block Time Profile

1,1 MAIN ENG2

MAIN ENG
FUEL
1 SYSTEM2

MAIN ENG
LUBOIL SYS2
0,9
MAIN ENG
COOLING
0,8 WATER2
MAIN ENG LUB
OIL TEMP2
0,7
MAIN ENG
CHARGE AIR
Unreliability

SYSTEM2
0,6
MAIN ENG
START SYS2
0,5 MAIN ENG SEA
WATER2

0,4

0,3

0,2

0,1

0
0 5256 10512 15768 21024 26280 31536 36792 42048 47304 52560

Time

Figure 6.8 : Main Engine No:2 unreliability-time diagram.

Sub-systems’ contribution to unreliabilities of Main Engines are shown on Figures

6.7 and 6.8 As shown on diagram, unreliabilities of the sub-systems increase with
working hours.

38
6.3.3.2 Contribution of steering gear sub-system

Result summary of steering gear sub-system is shown on Table 6.2. As seen on Table
6.2, almost all sub-systems of steering gear have unavailability values of zero.
System unavailability and unreliability are affected by failures of S/G electric supply
section board.

Table 6.2 : Steering Gear System Result Summary

No.of
Unavailability Unreliability Expected TDT MTTF MTTR
Failures
Steering
Gear 3,425E-05 0,9502 3 1,791 1,751E+04 0,6
System
S/G Pumps 0 0,003622 0,003628 0 1,441E+07 -
S/G
0 0,000454 0,0004541 0 1,151E+08 -
Hyd.Sys
S/G Room
0 0,0001325 0,0001325 0 3,945E+08 -
Components

The availability value for steering gear sub-system is calculated as 0,99966.

Unreliability of steering gear sub-system versus working hour is shown on Figure
6.9. As expected, because of constant failure rate, reliability of the system decreases
with time.

Block Time Profile

STEERING
1 GEAR

S/G PUMPS
0,9
S/G HYD SYS

S/G ROOM
0,8 COMPONENTS

0,7

0,6
Unreliability

0,5

0,4

0,3

0,2

0,1

0
0 5256 10512 15768 21024 26280 31536 36792 42048 47304 52560

Time

Figure 6.9 : Unreliability of steering gear sub-system.

39
6.3.3.3 Contribution of electric power sub-system

Result summary of RWB for electric power sub-system is shown on Table 6.3.

Table 6.3 : Electric power sub-system’s result summary.

No.of
Unavailability Unreliability Expected TDT MTTF MTTR
Failures
Electric
Power 9,845E-05 0,9998 8,317 5,149 6316 0,622
System
GENSET
0,0003842 1 34,98 20,09 1501 0,5773
No:1
GENSET
0,008614 1 41,64 450,5 1251 10,87
No:2
Main
3,805E-05 0,9933 5 1,99 1,051E+04 0,4
Switchboard
Section
0,0001332 0,9997 7,999 6,964 6565 0,875
Boards
Emergency
0,5
Power 5,707E-05 0,9975 6 2,985 8754
Supply

Unavailabilities of electric power sub-systems are shown on Figure 6.11. Although

unavailability of Genset No:2 is higher than other sub-systems, total unvailability is
low, since Genset No:2 is connected to Genset No:1 in parallel.

Figure 6.10 : Unavailabilities of electric power sub-systems.

40
Unreliabilities of electric power sub-systems are shown on Figure 6.12. Since
Gensets have generators and diesel engines total reliabilities get higher with time and
cut sets unreliabilities cause system unreliability to become high at the end of project
time.

Unavailabilities and unreliabilities of Genset No:1 and No:2 are shown in Figures
6.13, 6.14, 6.15 and 6.16 respectively. Although unavailability of Gensets are low,
unreliability values get higher with working hour. As indicated in description of
reliability, reliability values represent the probability of failure occurance in system.
Since availabilities are high, we may conclude that gensets are properly working in
ship system. Because with a constant failure rate, it is normal to have lower
reliabilities at the end of the project time.

Block Time Profile

ELECTRIC
1,1 POWER
SYSTEM

1 GENSET1

MAIN SWITCH
BOARD
0,9
SECTION
BOARDS
0,8 EMERGENCY
POWER
SUPPLY
0,7
GENSET2
Unreliability

0,6

0,5

0,4

0,3

0,2

0,1

0
0 5256 10512 15768 21024 26280 31536 36792 42048 47304 52560

Time

Figure 6.11 : Unreliabilities of electric power sub-systems.

41
 Figure 6.12 : GENSET No:1 unavailability.

Block Time Profile

1 GENSET1

GENEDIESEL 1

0,9 GENERATOR1

GENSET FUEL
SYS1
0,8
GENSET LUB
OIL SYS1
0,7 GENSET
COOLING
WATER1
0,6 GENSET
START SYS1
Unreliability

GENSET LUB
0,5 OIL TEMP 1
GENSET SEA
WATER1
0,4

0,3

0,2

0,1

0
0 5256 10512 15768 21024 26280 31536 36792 42048 47304 52560

Time

Figure 6.13 : GENSET No:1 unreliability.

42
 Figure 6.14 : GENSET No:2 unavailability.

Block Time Profile

1,1 GENSET2

GENEDIESEL 2
1
GENERATOR2

GENSET FUEL
0,9 SYS2

GENSET LUB
0,8 OIL SYS2
GENSET
COOLING
0,7 WATER2
GENSET
START SYS2
Unreliability

0,6
GENSET LUB
OIL TEMP 2
0,5

0,4

0,3

0,2

0,1

0
0 5256 10512 15768 21024 26280 31536 36792 42048 47304 52560

Time

Figure 6.15 : GENSET No:2 unreliability.

43
6.3.3.4 Contribution of damage control sub-system

Damage control sub-system consist of components related with especially ship’s

floatability and preventive considerations against fire-fighting and water disharge
systems. Other system is fuel transfer system which is necessary for ship’s
propulsion and electric power systems. RWB analze result summary is illustrated on
Table 6.4.

Table 6.4 : Damage control sub-system result summary.

No.of
Unavailability Unreliability Expected TDT MTTF MTTR
Failures
Damage
Control 0,000236 1 16,03 12,34 3275 0,7739
System
Fire
Fighting &
Water 4,858E-05 0,9822 4,028 2,54 1,304E+04 0,6338
Discharge
System
Watertight
7,229E-05 0,9999 8,999 3,781 5838 0,4222
Departments

Unavailabilities and unreliabilities of Damage Control Sub-systems are shown

respectively on Figures 6.17 and 6.18.

Figure 6.16 : Damage control unavailability.

44
 Block Time Profile
DAMAGE
1 CONTROL
SYSTEM
FIRE FIGHTING
0,9 & WATER
DISCHARGE
SYSTEM
0,8 DO TRA SYS

W/T DEPTS
0,7

0,6
Unreliability

0,5

0,4

0,3

0,2

0,1

0
0 5256 10512 15768 21024 26280 31536 36792 42048 47304 52560

Time

Figure 6.17 : Damage control unreliability.

45
46
7. FAULT TREE CONSTRUCTION

RWB Fault Tree analysis calculates unavailability, failure frequency and

unreliability of project. RWB has facility to convert RBD to FT diagram. Since FT
generated by RBD is difficult to follow in determining the reason of the failure in
ship’s main sub-systems, a simplified FT for the project has been prepared in RWB.

The simplified FT diagrams are shown in Appendix I. In construction process, logic

of RBD has been used. Serially arranged events and systems are represented by OR
gates and parallel arranged events and sub-systems are represented by AND gates.
Top gate represents “ship cannot accomplish the mission” event. When ship cannot
accomplish the mission, at least one of four sub-system may have failure. If FT is
followed from top to bottom, failure causing the mission interrupt or making system
unavailable may be determined.

An analysis has been carried out for the simplified FT and the results generated have
been checked against the results of RBD as shown in Table 7.1. It is approved that
the simplification of original FT converted from RBD is satisfactory..

Table 7.1 : RBD and FT analaysis results.

No.of
System Unavailability Unreliability
Expected Failures
RBD/ FT RBD FT RBD FT RBD FT
Total Ship 0,0003726 0,0003726 1 1 27,48 27,48
Propulsion
3,87E-06 3,867E-06 0,1305 0,1302 0,1398 0,139
System
Steering
3,425E-05 3,425E-05 0,9502 0,9502 3 3
Gear
Electric
Power 9,845E-05 9,844E-05 0,9998 0,9998 8,317 8,316
System
Damage
0,000236 0,000236 1 1 16,03 16,03
Control

47
48
8. CONCLUSIONS

8.1 Unavailability Results

According to the analysis of the sample ship type chosen for the project, Ship has
low unavailability value and number of expected failures calculated by RWB for
total ship system is not high for the selected project time of six years. Low
unavailability values may be interpreted that ship will be ready to accomplish the
mission for most of the time through the period considered.

When the unavailabilities of the main systems are examined, it is obvious that
damage control sub-system is most contributing one in increasing the unavailability
of ship system. The reason of this contribution may be explained by checking the
unavailabilities of damage control sub-systems. Water-tight compartments including
hatchways and portholes have high number of failures. Even though these systems do
not cause the mission interrupt directly, according to the regulations of naval ships,
water-tigthness between compartments is necessary for a naval ship to be missioned.
These kinds of failures are very important for the ship to go underway. Since in case
of fire or water flooding, these failures may cause huge damages, ship with these
kinds of failures is accepted as unavailable for the mission.

Ship propulsion system and steering gear system have 2500 working hours which are
projected to 52560 hours. These systems have also low unavailability values for the
selected project time. The reason for the low unavailability may be explained by the
age of the ships. Project time, which has been selected, is the period after first
overhaul of the ships.Systems are just at the beginning of the useful life described on
Figure 1.1 Bathtube curve. Probably low number of failures is due to the age of the
systems. Number of failures and unavailability may increase proportionally as the
system components age in future.

49
8.2 Unreliability Results

Unreliability values calculated by RWB show that unreliabilities of the sub-systems

are increasing with time as expected. It is usual that unreliability of a system with
contant failure rate, increases with working hours because of the definition of
unreliability, Equation 6.1. Unreliability of propulsion system is so high, since one
propulsion unit is accepted enough for accomplishing the mission. In case two
propulsion unit was mandatory for the mission, the propulsion system should be
constructed in a serial arrangement, and then unreliability of propulsion system
would be higher.

8.3 Suggestions

In order to decrease unavailability of the ship, standby components can be designed

for the components which decrease the availability of the sub-systems. As an
example, additional submersible pump for water discharge system would increase the
availability of damage control sub-system.

Another solution to increase availabilities of the sub-systems is to make additional

preventive maintenance for the components which cause system failure. For instance,
according to the results compiled by RWB, especially leakage problems cause
unavailability increase. Preventive maintenance would decrease the number of
failures occured in piping systems, so availability of the system increases.

Unreliability indicates a probability of failure for the systems. Since all the system
components are repairable or replacable, maintainability of the system can be
assured. Although reliability of the system decreases with time, availability is
constant, because of constant failure rates. In order to increase reliability, the period
between two overhaul can be decreased or maintenance procedures can be put into
effect for the key components like engines, generators and steering gear components.

50
REFERENCES

Molland, T, (2008). The Maritime Engineering Reference Book: A Guide to Ship

Design, Construction and Operation, Elsevier Jordan Hill, Burlington,
USA.

Andrews , J.D. and Moss , T.R., (2002). Reliability and Risk Assessment,
Professional Engineering Publishing Ltd., London and Bury St
Edmunds, UK .

O’Connor P. D.T, (1981). Practical Reliability Engineering, John Wiley & Sons,
Newyork,USA.

MIL-STD-721C, (1981). Military Standarts Definition of Terms for Reliability and

Maintanability, Department of Defence , United States of America.

MIL-STD-756B, (1981). Military Standart Reliability Modelling and Prediction,

Department of Defence , United States of America.

Nachlas, J.A., (2005). Reliability Engineering : Probalistic Models and

Maintanance Methods, Taylor & Francis, Boca Raton, USA.

Govil A.K., (1983). Reliability Engineering, McGraw-Hill, New Delhi, India.

Lewis, E.E., (1996). Introduction to Reliability Engineering, John Wiley & Sons,
Newyork,USA.

Bazovsky, I., (1961). Reliability Theory and Practice. Prentice Hall, Englewood
Cliffs New Jersey

MIL (1960). Buships Specification . Department of Defence , United States of

America , MIL-R-22732 .

Ang, A.H.S. and Tang, W.H., (1984). Probability Concepts in Engineering

Planning and Design, John Wiley & Sons , UK .

Best, P.J. and Davies, W.B., (1999). The Assessment of Safety for Vessels in
Service: Practical Examples of the Application of FSA Techniques
from Inland Vessels to Ocean Going Ferries . Transactions of IMarE ,
Vol. 111 , No. 2 , pp. 51 – 58 .

Isograph, (2011). Reliability Workbench Version 11 Incorporating FaultTree+ User

Guide.

51
Baliwangi, L., (1999). Stuady of Reliability, Maintainability and Availability: A
Case Study of a Shuttle Tanker Propulsion System, Faculty of
Engineering & Applied Sciences, Memorial University of
Newfoundland, Canada.

Alven W.H. Von, (1964). Reliability Engineering, ARINC Research

Corporation,Prentice Hall Inc, New Jersey.

DoD, (2005). DoD Guide for Achieving Reliability, Availability, and

Maintainability, Department of Defence , United States of America.

52
APPENDICES

APPENDIX A: Failure Model List İncluding MTTF and MTTR Table on CD

APPENDIX B: Cut Sets Unavailability and Failure Frequency Table on CD
APPENDIX C: Events Generic Failure Models on CD
APPENDIX D: Events Failure Rate - MTTF – MTTR List on CD
APPENDIX E: Events MTTF List on CD
APPENDIX F: Events MTTR List on CD
APPENDIX G: Reliability Block Diagrams
APPENDIX H: RBD Time Profile on CD
APPENDİX I : Fault Tree Diagrams

53
54
APPENDIX G

Reliability Block Diagrams

SHIP RELIABILITY

System SHIP RELIABILITY

Page 1 of 49

Page 2

SHIP UNAVAILABILITY
Total Ship System's Unavailability

Q=0,0003726

55
 Reliability Block Diagrams
SHIP RELIABILITY

Page 2 of 49
Sub-system SHIP UNAVAILABILITY See page 1

Page 3 Page 4 Page 5 Page 6

PROPULSION SYSTEM STEERING GEAR ELECTRIC POWER SYSTEM DAM AGE CONTROL SYSTEM

Propulsion System Steering Gear Electric Power Damage Control

Failure Failure System Failure System Failure

Q=3,87E-06 Q=3,425E-05 Q=9,845E-05 Q=0,000236

56
 Reliability Block Diagrams
SHIP RELIABILITY

Page 3 of 49
Sub-system PROPULSION SYSTEM See page 2

Page 7
MAIN ENG1
MAIN ENGINE
Failure

Q=0,002248

Page 31
MAIN ENG2
MAIN ENGINE
Failure

Q=0,00172

57
 Reliability Block Diagrams
SHIP RELIABILITY

Page 4 of 49
Sub-system STEERING GEAR See page 2

Page 15
S TEERING GEAR S ECTION BOARD S/G PUMPS
Electric Supply S/G Pump Failure
Problem on S/G
Section Board
STEERING GEAR Q=0
SECTION BOARD
MTTF=26280
Q=1,903E-05
Page 16 Page 17
S/G HYD SYS S/G PIPING S/G ROOM COMPONENTS
Hydraulic System Leakage on S/G S/G Room Hydraulic
Failure Hydraulic Piping Components Failure

Q=0 S/G PIPING Q=0

MTTF=17520
Q=3,425E-05
MANUAL S/G
Manual System
Failure

MANUAL S/G
MTTF=52560
Q=0

58
 Reliability Block Diagrams
SHIP RELIABILITY

Page 5 of 49
Sub-system ELECTRIC POWER SYSTEM See page 2

Page 8 Page 10
GENSET1 SECTION BOARDS
No Electric Priorr Section Boards
Production Failure

Q=0,0003842 Page 9 Q=0,0001332

M AIN SWITCH BOARD ELEC WIRING NETWORK
Main Switch Board Electrical Wiring
Failure Failure
Page 41
GENSET2 Q=3,805E-05 ELEC WIRING Page 11
No Electric NETWORK EM ERGENCY POWER SUPPLY
Production MTTF=17520 Emergency Power Supply
Q=5,707E-05 Failure
Q=0,008614
Q=5,707E-05

59
 Reliability Block Diagrams
SHIP RELIABILITY

Page 6 of 49
Sub-system DAMAGE CONTROL SYSTEM See page 2

Page 12 Page 13 Page 14

FI RE FI GHTI NG & WATER DI SCHARGE SYSTEM
DO TRA SYS W/T DEPTS
Fire Fighting & DIESEL OIL WATER-TIGHT
Water Discharge TRANSFER DEPARTMENTS
System Failure SYSTEM
Q=4,858E-05 Q=0,0001152 Q=7,229E-05

60
 Reliability Block Diagrams
SHIP RELIABILITY

Sub-system MAIN ENG1 See page 3 Page 7 of 49

Page 18 Page 19 Page 20 Page 21 Page 22 Page 23

M AINENGF UEL S YSTEM1 M AIN ENG LUBOIL S YS 1 M A I N E N G C O O L I NG WATER1 M AINENGLUBOIL TEMP1 M AI N ENG CHARGE AI R SYSTEM 1 M AIN ENG S TART S YS 1 M AIN ENG ALARM S YS 1 M AI N ENG LUB OI L M I XED WATER 1

No Fuel Supply Lub.Oil Pres s ure Fres h Water Temp Lub Oil Temp High Air Supply Failure Starter Failure Alarm Syatem Water M ixed into
Low High Failure Lub Oil

Q=0,0003234 Q=0 Q=0 Q=0 Q=0,001823 Q=7,61E-06 M AIN ENG M AIN ENG LUB
ALARM SYS1 OIL M IXED
M TTF=17520 WATER 1
Q=3,805E-05 M TTF=26280
Q=5,707E-05

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Page 8 of 49
Sub-system GENSET1 See page 5

Page 25 Page 26
GENEDIESEL 1 GENERATOR1 GENERATOR WIRING 1
Engine Failure Generator Does Not Electrical Wiring
Produce Electircity Failure

Q=0,0003272 Q=0 GENERATOR

WIRING 1
MTTF=26280
Q=5,707E-05

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Page 9 of 49
Sub-system MAIN SWITCH BOARD See page 5

MAIN SWITCHES SEC BOARD SWITCHES SYNC UNIT

Main Switches Section Boards' Syncrontion Unit
Failure Swithes Failure Failure

MAIN SWITCHES SEC BOARD SYNC UNIT

MTTF=26280 SWITCHES MTTF=52560
Q=1,903E-05 MTTF=26280 Q=0
Q=1,903E-05

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Page 10 of 49
Sub-system SECTION BOARDS See page 5

STEERING GEAR SECTION BOARD NAVIGATIONAL AS S ETS S ECTION BOARD ENGINE ROOM SECTİON BOARD

Electric Supply Electric Supply Electric Supply

Problem on S/G Problem on Problem on Engine
Navigational Assets
Section Board Section Board Room Section Board
STEERING GEAR NAVIGATIONAL ENGINE ROOM
SECTION BOARD ASSETS SECTION SECTİON BOARD
MTTF=26280 BOARD MTTF=26280
Q=1,903E-05 MTTF=13140 Q=5,707E-05
Q=5,707E-05

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Page 11 of 49
Sub-system EMERGENCY POWER SUPPLY See page 5

EMER BATTERIES EMER SUPPLY WIRINGS

Battery Voltage Low Emergency Wiring
Failure

EMER BATTERIES EMER SUPPLY

MTTF=13140 WIRINGS
Q=4,756E-05 MTTF=26280
Q=9,513E-06

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Page 12 of 49
Sub-system FIRE FIGHTING & WATER DISCHARGE SYSTEM See page 6

F IXED WATER DIS CHARGE S YS TEM

FIRE PUM P ELEC M OTOR 1 FIRE PUMP 1 Water Discharge

Fire Pump Electric Pump does not Ejector Does Not
Motor Does Not function Function
Function FIXED WATER
FIRE PUMP ELEC FIRE PUMP 1 DISCHARGE FIRE FIGHTING PIPING
MOTOR 1 MTTF=17520 SYSTEM Leakage on
MTTF=52560 Q=0,004545 MTTF=17520 Fire-Figthing Piping
Q=0 Q=9,512E-05

FIRE PUM P ELEC M OTOR 2 FIRE PUMP 2 S UBM ERS IBLE ELECTRICAL P UM P FIRE FIGHTING
Fire Pump Electric Pump does not Submersible Electric PIPING
Motor Does Not function Pump Does Not MTTF=13140
Function Function Q=3,805E-05
FIRE PUMP ELEC FIRE PUMP 2 SUBMERSIBLE
MOTOR 2 MTTF=52560 ELECTRICAL
MTTF=26280 Q=0 PUMP
Q=0,002278 MTTF=26280
Q=0,001823

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Page 13 of 49
Sub-system DO TRA SYS See page 6

DO TRANS F ER P UM P ELECTRIC M OTOR DO TRANSFER PUMP

DO Transfer Pump DO Transfer Pump
Electric Motor Does Does Not Function
Not Function
DO TRANSFER DO TRANSFER DO TRANSFER SYSTEM PIPING

PUMP ELECTRIC PUMP Leakage on DO

MOTOR MTTF=26280 Transfer System
MTTF=26280 Q=0,0009124 Piping
Q=0,001823
DO TRANSFER
DO TRANSFER HAND PUMP SYSTEM PIPING
DO Transfer Hand MTTF=17520
Pump Does Not Q=0,0001141
Function
DO TRANSFER
HAND PUMP
MTTF=26280
Q=0,0003804

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Page 14 of 49
Sub-system W/T DEPTS See page 6

PORTHOLES HATCHWAYS
Tigthness Problem Tigthness Problem
on Portholes on Hatchways

PORTHOLES HATCHWAYS
MTTF=10512 MTTF=13140
Q=1,903E-05 Q=5,327E-05

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Page 15 of 49
Sub-system S/G PUMPS See page 4

S/G PUMP ELEC MOTOR1 S/G HYD PUMP1

Electric Motor Hydraulic Pump
Failure Failure

S/G PUMP ELEC S/G HYD PUMP1

MOTOR1 MTTF=52560
MTTF=52560 Q=0
Q=0

S/G PUMP ELEC MOTOR2 S/G HYD PUMP2

Electric Motor Hydraulic Pump
Failure Failure

S/G PUMP ELEC S/G HYD PUMP2

MOTOR2 MTTF=52560
MTTF=26280 Q=0
Q=0,001823

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Page 16 of 49
Sub-system S/G HYD SYS See page 4

S/G HYD SYS PUM P ON BRIDGE

S/G Hydraulic Pump

Does Not Function

S/G HYD SYS

PUMP ON BRIDGE
MTTF=26280
Q=0,0004564

S/G HYD PUMP IN S/G ROOM

S/G Hyd Pump Does

Not Function in S/G
Room
S/G HYD PUMP IN
S/G ROOM
MTTF=52560
Q=0

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Page 17 of 49
Sub-system S/G ROOM COMPONENTS See page 4

S/G SELENOID VALVE GROUP 1

S/G HYD PISTON 1
S/G Selenoid Valve S/G Hydraulic
Group 1 Failure Piston 1 Failure

S/G SELENOID S/G HYD PISTON 1

VALVE GROUP 1 MTTF=52560
MTTF=52560 Q=0
Q=0

S/G SELENOID VALVE GROUP 2 S/G HYD PISTON 2

S/G Selenoid Valve S/G Hydraulic
Group 2 Failure Piston 2 Failure

S/G SELENOID S/G HYD PISTON 2

VALVE GROUP 2 MTTF=26280
MTTF=26280 Q=9,512E-05
Q=3,805E-05

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Page 18 of 49
Sub-system MAIN ENG FUEL SYSTEM1 See page 7

M AINENGDUBLEXF UEL F ILT A1

Fuel Filter Clogged

M AIN ENG F UELS RVC P UM P 1 MAIN ENG M AIN ENG FUEL PUM P1 M AIN ENG INJ ECTORS1 M AIN ENG P IP ING F UEL S YS 1

Fuel Service Pump DUBLEX FILTER Bosch Type Fuel Some injectors do Leakage on fuel
Failure A1 Pump Failure not spray fuel pipes and
No Fuel at inlet of filter MTTF=26280 connections
Q=5,708E-06
MAIN ENG FUEL MAIN ENG FUEL MAIN ENG MAIN ENG PIPING
SRVC PUMP1 M AINENGDUBLEXF UEL F ILT B1
PUMP1 INJECTORS1 FUEL SYS1
MTTF=26280 Fuel Filter Clogged MTTF=52560 MTTF=17520 MTTF=52560
Q=0,0002283 Q=0 Q=9,512E-05 Q=0

MAIN ENG
DUBLEX FUEL
FILT B1
MTTF=26280
Q=5,708E-06

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Sub-system MAIN ENG LUBOIL SYS1 See page 7 Page 19 of 49

Page 21
M AINENGS UM P OIL LEVEL1 M AIN ENG FILTER OIL1 M AIN ENG LUB OIL TEM P 1 M AIN ENG LUB OIL P UM P 1 M AINENGM AINBEARINGS1 M AINENGCONRODBEARINGS1 M AIN ENG PIPING OIL1
Lub Oil level Low Oil Filter Clogged Lub Oil Temp High Lubricating Oil Main Bearings Worn Connecting Rod Leakage at Oil
Pump Failure Bearings Worn System Piping

MAIN ENG SUMP MAIN ENG Q=0 MAIN ENG LUB MAIN ENG MAIN MAIN ENG CON MAIN ENG PIPING
OIL LEVEL1 FILTER OIL1 OIL PUMP1 BEARINGS1 ROD BEARINGS1 OIL1
MTTF=52560 MTTF=52560 MTTF=52560 MTTF=52560 MTTF=52560 MTTF=52560
Q=0 Q=0 Q=0 Q=0 Q=0 Q=0

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Page 20 of 49
Sub-system MAIN ENG COOLING WATER1 See page 7

Page 24
M AIN ENG SEA WATER1 MAIN ENG F/W HEX1 MAIN ENG F/W LEVEL1 M AIN ENG THERM OSTAT1 MAIN ENG F/W PUMP1
Sea Water Supply F/W HEX Clogged F/W Level Low Thermostat Stucked F/W Pump Failure
Loss Closed

Q=0 MAIN ENG F/W MAIN ENG F/W MAIN ENG MAIN ENG F/W
HEX1 LEVEL1 THERMOSTAT1 PUMP1
MTTF=52560 MTTF=52560 MTTF=52560 MTTF=52560
Q=0 Q=0 Q=0 Q=0

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Page 21 of 49
Sub-system MAIN ENG LUB OIL TEMP1 See pages 7,19

Page 24
MAIN ENG SEA WATER1 MAIN ENG LUB OIL HEX1 MAIN ENG SUMP OIL LEVEL1

Sea Water Supply Lub Oil HEX Lub Oil level Low
Loss Clogged

Q=0 MAIN ENG LUB MAIN ENG SUMP

OIL HEX1 OIL LEVEL1
MTTF=52560 MTTF=52560
Q=0 Q=0

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Page 22 of 49
Sub-system MAIN ENG CHARGE AIR SYSTEM1 See page 7

MAIN ENG AIR FILTER1 MAIN ENG SUPERCHARGER1

Air Filter Clogged Supercharger Failure

MAIN ENG AIR MAIN ENG

FILTER1 SUPERCHARGER1
MTTF=52560 MTTF=26280
Q=0 Q=0,001823

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Page 23 of 49
Sub-system MAIN ENG START SYS1 See page 7

MAIN ENG START BATTERIES1 MAIN ENG START MOTOR 1 MAIN ENG START SWITCH 1 M AIN ENG START SYS WIRING 1

Battery Voltage Low Start Motor Failure Start Switch Failure Start System Wiring
Failure

MAIN ENG START MAIN ENG START MAIN ENG START MAIN ENG START
BATTERIES1 MOTOR 1 SWITCH 1 SYS WIRING 1
MTTF=52560 MTTF=52560 MTTF=52560 MTTF=26280
Q=0 Q=0 Q=0 Q=7,61E-06

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Page 24 of 49
Sub-system MAIN ENG SEA WATER1 See pages 20,21

M AIN ENG S/W SUCTION VALVE1 MAIN ENG S/W PUMP1

Suction Valve S/W Pump Failure
Stucked Closed
MAIN ENG S/W PIPING1
MAIN ENG S/W MAIN ENG S/W Leakage on S/W
SUCTION VALVE1 PUMP1 Piping
MTTF=52560 MTTF=52560
Q=0 Q=0
MAIN ENG S/W
PIPING1
MAIN ENG EMER S/W SUPPLY1 MTTF=52560
Q=0
Emergency Sea
Water Supply Loss

MAIN ENG EMER

S/W SUPPLY1
MTTF=52560
Q=0

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Sub-system GENEDIESEL 1 See page 8 Page 25 of 49

Page 27 Page 28 Page 29 Page 39 Page 30

GENSET FUEL SYS1 GENS ET LUB OIL S YS 1 GENS ET COOLINGWATER1 GENS ET LUBOIL TEMP 1 GENSET AIR SYS1 G EN S ET S TA R T S YS1 G EN S ET A LA R M SYS1 G ENSETLUBOI LM I XEDWI THWATER1

No Fuel Supply Lub Oil Pres s ure Fres h Water Temp Lub Oil Temp High Air Filter Clogged Starter Failure Alarm Sys tem Water M ixed into
Low High Failure Lub Oil

Q=0,0001065 Q=7,597E-06 Q=0,0001598 Q=7,597E-06 GENSET AIR SYS1 Q=3,805E-06 GENSET ALARM GENSET LUB OIL
M TTF=52560 SYS1 M IXED WITH
Q=0 M TTF=26280 WATER 1
Q=1,903E-05 M TTF=26280
Q=3,805E-05

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Page 26 of 49
Sub-system GENERATOR1 See page 8

GENSET SLIP RING1 GENSET BRUSHES1 GENSET EXCITING CURRENT 1

GENSET1 Slip Ring GENSET 1 Brush GENSET 1 No

Failure Failure Exciting Current

GENSET SLIP GENSET GENSET

RING1 BRUSHES1 EXCITING
MTTF=52560 MTTF=52560 CURRENT 1
Q=0 Q=0 MTTF=52560
Q=0

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Page 27 of 49
Sub-system GENSET FUEL SYS1 See page 25

GENS ET DUBLEX F ILTER A1

Dublex Filter
Clogged

GENSET FUELSRVCPUM P 1 GENSET DUBLEX GENSET FUEL PUMP1 GENSET INJECTORS1 GENSET PIPING FUEL 1
Fuel Service Pump FILTER A1 Bosch Type Fuel Some Injectors do Leakage on fuel
Failure MTTF=26280 Pump Failure not spray fuel pipes and
No Fuel at Inlet of Filter Q=5,708E-06 connections
GENSET GENSET DUBLEX FILTER B1 GENSET FUEL GENSET GENSET PIPING
FUELSRVCPUMP Dublex Filter PUMP1 INJECTORS1 FUEL 1
1 Clogged MTTF=52560 MTTF=26280 MTTF=26280
MTTF=52560 Q=0 Q=9,512E-05 Q=1,142E-05
Q=0
GENSET DUBLEX
FILTER B1
MTTF=52560
Q=0

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Sub-system GENSET LUB OIL SYS1 See page 25 Page 28 of 49

Page 39
GENS ET S UM P OIL LEVEL1 GENSET OIL FILTER 1 GENS ET LUB OIL TEM P 1 GENS ET LUB OIL P UM P 1 GENS ET M AIN BEARINGS 1 GENS ET CONRODBEARINGS 1 GENSET PIPING OIL 1
Lub Oil level Low Oil Filter clogged Lub Oil Temp High Lubricating Oil Main Bearings Worn Connecting Rod Leakage at Oil
Pump Failure Bearings Worn System Piping

GENSET SUMP GENSET OIL Q=7,597E-06 GENSET LUB OIL GENSET MAIN GENSET CON GENSET PIPING
OIL LEVEL1 FILTER 1 PUMP 1 BEARINGS 1 ROD BEARINGS 1 OIL 1
MTTF=52560 MTTF=52560 MTTF=52560 MTTF=52560 MTTF=52560 MTTF=52560
Q=0 Q=0 Q=0 Q=0 Q=0 Q=0

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Page 29 of 49
Sub-system GENSET COOLING WATER1 See page 25

Page 40
GENSET SEA WATER1 GENSET F/W HEX 1 GENSET F/W LEVEL 1 GENSET THERMOSTAT 1 GENSET F/W PUMP 1
Sea Water Supply F/W HEX Clogged F/W Level Low Thermostat Stucked F/W Pump Failure
Loss Closed

Q=7,597E-06 GENSET F/W HEX GENSET F/W GENSET GENSET F/W

1 LEVEL 1 THERMOSTAT 1 PUMP 1
MTTF=52560 MTTF=52560 MTTF=52560 MTTF=26280
Q=0 Q=0 Q=0 Q=0,0001522

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Page 30 of 49
Sub-system GENSET START SYS1 See page 25

GENSET START BATTERIES 1 GENSET START MOTOR 1 GENSET START SWITCH 1 GENSET START SYS WIRING 1

Battery Voltage Low Start Motor Failure Start Switch Failure Start System Wiring
Failure

GENSET START GENSET START GENSET START GENSET START

BATTERIES 1 MOTOR 1 SWITCH 1 SYS WIRING 1
MTTF=26280 MTTF=52560 MTTF=52560 MTTF=52560
Q=3,805E-06 Q=0 Q=0 Q=0

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Sub-system MAIN ENG2 See page 3 Page 31 of 49

Page 32 Page 33 Page 34 Page 35 Page 36 Page 37

M AINENGF UEL S YSTEM2 M AIN ENG LUBOIL S YS 2 M A I N E N G C O O L I NG WATER2 M AINENGLUBOIL TEMP2 M AI N ENG CHARGE AI R SYSTEM 2 M AIN ENG S TART S YS 2 M AIN ENG ALARM S YS 2 M AI N ENG LUB OI L M I XED WATER 2

No Fuel Supply Lub.Oil Pres s ure Fres h Water Temp Lub Oil Temp High Air Supply Failure Starter Failure Alarm Syatem Water M ixed into
Low High Failure Lub Oil

Q=0,0009656 Q=1,522E-05 Q=0,0002245 Q=1,522E-05 Q=3,805E-06 Q=0,0004621 M AIN ENG M AIN ENG LUB
ALARM SYS2 OIL M IXED
M TTF=10512 WATER 2
Q=6,468E-05 M TTF=52560
Q=0

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Page 32 of 49
Sub-system MAIN ENG FUEL SYSTEM2 See page 31

M AINENGDUBLEXF UEL F ILT A2

Fuel Filter Clogged

M AIN ENG F UELS RVC P UM P 2 MAIN ENG M AIN ENG FUEL PUM P2 M AIN ENG INJ ECTORS2 M AIN ENG P IP ING F UEL S YS 2

Fuel Service Pump DUBLEX FUEL Bosch Type Fuel Some injectors do Leakage on fuel
Failure FILT A2 Pump Failure not spray fuel pipes and
No Fuel at inlet of filter MTTF=52560 connections
Q=0
MAIN ENG MAIN ENG FUEL MAIN ENG MAIN ENG PIPING
FUELSRVC M AINENGDUBLEXF UEL F ILT B2
PUMP2 INJECTORS2 FUEL SYS2
PUMP2 Fuel Filter Clogged MTTF=26280 MTTF=26280 MTTF=26280
MTTF=52560 Q=0,0009124 Q=3,805E-05 Q=1,522E-05
Q=0
MAIN ENG
DUBLEX FUEL
FILT B2
MTTF=26280
Q=5,708E-06

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Sub-system MAIN ENG LUBOIL SYS2 See page 31 Page 33 of 49

Page 35
M AINENGS UM P OIL LEVEL2 M AIN ENG FILTER OIL2 M AIN ENG LUB OIL TEM P 2 M AIN ENG LUB OIL P UM P 2 M AINENGM AINBEARINGS2 M AINENGCONRODBEARINGS2 M AIN ENG PIPING OIL2
Lub Oil level Low Oil Filter Clogged Lub Oil Temp High Lubricating Oil Main Bearings Worn Connecting Rod Leakage at Oil
Pump Failure Bearings Worn System Piping

MAIN ENG SUMP MAIN ENG Q=1,522E-05 MAIN ENG LUB MAIN ENG MAIN MAIN ENG CON MAIN ENG PIPING
OIL LEVEL2 FILTER OIL2 OIL PUMP2 BEARINGS2 ROD BEARINGS2 OIL2
MTTF=52560 MTTF=52560 MTTF=52560 MTTF=52560 MTTF=52560 MTTF=52560
Q=0 Q=0 Q=0 Q=0 Q=0 Q=0

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Page 34 of 49
Sub-system MAIN ENG COOLING WATER2 See page 31

Page 38
M AIN ENG SEA WATER2 MAIN ENG F/W HEX2 MAIN ENG F/W LEVEL2 M AIN ENG THERM OSTAT2 MAIN ENG F/W PUMP2
Sea Water Supply F/W HEX Clogged F/W Level Low Thermostat Stucked F/W Pump Failure
Loss Closed

Q=1,522E-05 MAIN ENG F/W MAIN ENG F/W MAIN ENG MAIN ENG F/W
HEX2 LEVEL2 THERMOSTAT2 PUMP2
MTTF=26280 MTTF=52560 MTTF=52560 MTTF=26280
Q=5,707E-05 Q=0 Q=0 Q=0,0001522

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Page 35 of 49
Sub-system MAIN ENG LUB OIL TEMP2 See pages 31,33

Page 38
MAIN ENG SEA WATER2 MAIN ENG LUB OIL HEX2 MAIN ENG SUMP OIL LEVEL2

Sea Water Supply Lub Oil HEX Lub Oil level Low
Loss Clogged

Q=1,522E-05 MAIN ENG LUB MAIN ENG SUMP

OIL HEX2 OIL LEVEL2
MTTF=52560 MTTF=52560
Q=0 Q=0

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Page 36 of 49
Sub-system MAIN ENG CHARGE AIR SYSTEM2 See page 31

MAIN ENG AIR FILTER2 MAIN ENG SUPERCHARGER2

Air Filter Clogged Supercharger Failure

MAIN ENG AIR MAIN ENG

FILTER2 SUPERCHARGER2
MTTF=26280 MTTF=52560
Q=3,805E-06 Q=0

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Page 37 of 49
Sub-system MAIN ENG START SYS2 See page 31

MAIN ENG START BATTERIES2 MAIN ENG START MOTOR 2 MAIN ENG START SWITCH 2 M AIN ENG START SYS WIRING 2

Battery Voltage Low Start Motor Failure Start Switch Failure Start System Wiring
Failure

MAIN ENG START MAIN ENG START MAIN ENG START MAIN ENG START
BATTERIES2 MOTOR 2 SWITCH 2 SYS WIRING 2
MTTF=52560 MTTF=26280 MTTF=26280 MTTF=52560
Q=0 Q=0,0004564 Q=5,708E-06 Q=0

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Page 38 of 49
Sub-system MAIN ENG SEA WATER2 See pages 34,35

M AIN ENG S/W SUCTION VALVE2 MAIN ENG S/W PUMP2

Suction Valve S/W Pump Failure
Stucked Closed
MAIN ENG S/W PIPING2
MAIN ENG S/W MAIN ENG S/W Leakage on S/W
SUCTION VALVE2 PUMP2 Piping
MTTF=26280 MTTF=52560
Q=1,522E-05 Q=0
MAIN ENG S/W
MAIN ENG EMER S/W SUPPLY2 PIPING2
Emergency Sea MTTF=17520
Water Supply Loss Q=1,522E-05

MAIN ENG EMER

S/W SUPPLY2
MTTF=52560
Q=0

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Page 39 of 49
Sub-system GENSET LUB OIL TEMP 1 See pages 25,28

Page 40
GENSET SEA WATER1 GENSET LUB OIL HEX1 GENSET SUMP OIL LEVEL1

Sea Water Supply Lub Oil HEX Lub Oil level Low
Loss Clogged

Q=7,597E-06 GENSET LUB OIL GENSET SUMP

HEX1 OIL LEVEL1
MTTF=52560 MTTF=52560
Q=0 Q=0

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Page 40 of 49
Sub-system GENSET SEA WATER1 See pages 29,39

GENSET S/W SUCTION VALVE 1 GENSET S/W PUMP 1

Suction Valve S/W Pump Failure
Stcked Closed

GENSET S/W GENSET S/W

SUCTION VALVE PUMP 1
1 MTTF=26280
MTTF=52560 Q=1,903E-05 GENSET S/W PIPING 1
Q=0
Leakage on S/W
Piping
GENSET EMER S/W SUPPLY 1

Emergency Sea GENSET S/W

Water Supply Loss PIPING 1
MTTF=26325
Q=7,597E-06
GENSET EMER
S/W SUPPLY 1
MTTF=52560
Q=0

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Page 41 of 49
Sub-system GENSET2 See page 5

Page 42 Page 43
GENEDIESEL 2 GENERATOR2 GENERATOR WIRING 2
Engine Failure Generator Does Not Electrical Wiring
Produce Electircity Failure

Q=0,008614 Q=0 GENERATOR

WIRING 2
MTTF=52560
Q=0

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Sub-system GENEDIESEL 2 See page 41 Page 42 of 49

Page 44 Page 45 Page 46 Page 48 Page 47

GENSET FUEL SYS2 GENS ET LUB OIL S YS 2 GENS ET COOLINGWATER2 GENS ET LUB OIL TEM P 2 GENSET AIR SYS2 GENSET START SYS2 GENSET ALARM SYS2 GENSET LUB OI L M I XED WI TH WATER 2

No Fuel Supply Lub Oil Pres s ure Fres h Water Temp Lub Oil Temp High Air Filter Clogged Starter Failure Alarm Sys tem Water M ixed into
Low High Failure Lub Oil

Q=0,00435 Q=8,941E-05 Q=0,004191 Q=8,371E-05 GENSET AIR SYS2 Q=0 GENSET ALARM GENSET LUB OIL
M TTF=26280 SYS2 M IXED WITH
Q=9,513E-06 M TTF=52560 WATER 2
Q=0 M TTF=52560
Q=0

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Page 43 of 49
Sub-system GENERATOR2 See page 41

GENSET SLIP RING2 GENSET BRUSHES2 GENSET EXCITING CURRENT 2

GENSET 2 Slip GENSET 2 Brush GENSET 2 No

Ring Failure Failure Exciting Current

GENSET SLIP GENSET GENSET

RING2 BRUSHES2 EXCITING
MTTF=52560 MTTF=52560 CURRENT 2
Q=0 Q=0 MTTF=52560
Q=0

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Page 44 of 49
Sub-system GENSET FUEL SYS2 See page 42

GENS ET DUBLEX F ILTER A2

Dublex Filter
Clogged

GENSET FUELSRVCPUM P 2 GENSET DUBLEX GENSET FUEL PUMP2 GENSET INJECTORS2 GENSET PIPING FUEL 2
Fuel Service Pump FILTER A2 Bosch Type Fuel Some Injectors do Leakage on fuel
Failure MTTF=52560 Pump Failure not spray fuel pipes and
No Fuel at Inlet of Filter Q=0 connections
GENSET GENSET DUBLEX FILTER B2 GENSET FUEL GENSET GENSET PIPING
FUELSRVCPUMP Dublex Filter PUMP2 INJECTORS2 FUEL 2
2 Clogged MTTF=17520 MTTF=17520 MTTF=17520
MTTF=26280 Q=0,004093 Q=0,0001522 Q=3,044E-05
Q=7,61E-05
GENSET DUBLEX
FILTER B2
MTTF=26280
Q=5,708E-06

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Sub-system GENSET LUB OIL SYS2 See page 42 Page 45 of 49

Page 48
GENS ET S UM P OIL LEVEL2 GENSET OIL FILTER 2 GENS ET LUB OIL TEM P 2 GENS ET LUB OIL P UM P 2 GENS ET M AIN BEARINGS 2 GENS ET CONRODBEARINGS 2 GENSET PIPING OIL 2
Lub Oil level Low Oil Filter clogged Lub Oil Temp High Lubricating Oil Main Bearings Worn Connecting Rod Leakage at Oil
Pump Failure Bearings Worn System Piping

GENSET SUMP GENSET OIL Q=8,371E-05 GENSET LUB OIL GENSET MAIN GENSET CON GENSET PIPING
OIL LEVEL2 FILTER 2 PUMP 2 BEARINGS 2 ROD BEARINGS 2 OIL 2
MTTF=52560 MTTF=52560 MTTF=52560 MTTF=52560 MTTF=52560 MTTF=26280
Q=0 Q=0 Q=0 Q=0 Q=0 Q=5,708E-06

99
 Reliability Block Diagrams
SHIP RELIABILITY

Page 46 of 49
Sub-system GENSET COOLING WATER2 See page 42

Page 49
GENSET SEA WATER2 GENSET F/W HEX 2 GENSET F/W LEVEL 2 GENSET THERMOSTAT 2 GENSET F/W PUMP 2
Sea Water Supply F/W HEX Clogged F/W Level Low Thermostat Stucked F/W Pump Failure
Loss Closed

Q=7,61E-06 GENSET F/W HEX GENSET F/W GENSET GENSET F/W

2 LEVEL 2 THERMOSTAT 2 PUMP 2
MTTF=26280 MTTF=52560 MTTF=26280 MTTF=17520
Q=7,61E-05 Q=0 Q=1,522E-05 Q=0,004093

100
 Reliability Block Diagrams
SHIP RELIABILITY

Page 47 of 49
Sub-system GENSET START SYS2 See page 42

GENSET START BATTERIES 2 GENSET START MOTOR 2 GENSET START SWITCH 2 GENSET START SYS WIRING 2

Battery Voltage Low Start Motor Failure Start Switch Failure Start System Wiring
Failure

GENSET START GENSET START GENSET START GENSET START

BATTERIES 2 MOTOR 2 SWITCH 2 SYS WIRING 2
MTTF=52560 MTTF=52560 MTTF=52560 MTTF=52560
Q=0 Q=0 Q=0 Q=0

101
 Reliability Block Diagrams
SHIP RELIABILITY

Page 48 of 49
Sub-system GENSET LUB OIL TEMP 2 See pages 42,45

Page 49
GENSET SEA WATER2 GENSET LUB OIL HEX2 GENSET SUMP OIL LEVEL2

Sea Water Supply Lub Oil HEX Lub Oil level Low
Loss Clogged

Q=7,61E-06 GENSET LUB OIL GENSET SUMP

HEX2 OIL LEVEL2
MTTF=26280 MTTF=52560
Q=7,61E-05 Q=0

102
 Reliability Block Diagrams
SHIP RELIABILITY

Page 49 of 49
Sub-system GENSET SEA WATER2 See pages 46,48

GENSET S/W SUCTION VALVE 2 GENSET S/W PUMP 2

Suction Valve S/W Pump Failure
Stcked Closed
GENSET S/W PIPING 2
GENSET S/W GENSET S/W Leakage on S/W
SUCTION VALVE PUMP 2 Piping
2 MTTF=26280
MTTF=52560 Q=1,903E-05
Q=0 GENSET S/W
PIPING 2
GENSET EMER S/W SUPPLY 2 MTTF=26280
Q=7,61E-06
Emergency Sea
Water Supply Loss

GENSET EMER
S/W SUPPLY 2
MTTF=52560
Q=0

103
104
APPENDIX I

Fault Tree Diagrams

SHIP RELIABILITY

Ship cannot
accomplish
mission

SHIP UNAVAILABLE
Q=0,0003726

Propulsion Steering Gear Electric Power Damage Control

System Failure System Failure System Failure System Failure

PROPULSION SYSTEM STEERING GEAR ELECTRIC POWER SYSTEM DAMAGE CONTROL SYSTEM

Q=3,867E-06 Q=3,425E-05 Q=9,844E-05 Q=0,000236

Page 2 Page 3 Page 4 Page 5

105
 Fault Tree Diagrams
SHIP RELIABILITY

Propulsion
System Failure

1
PROPULSION SYSTEM
Q=3,867E-06

GT336 GT337

Main Engine Main Engine

No:1 Failure No:2 Failure

MAIN ENGINE NO:1 MAIN ENGINE NO:2

Page 16 Page 17

106
 Fault Tree Diagrams
SHIP RELIABILITY

Steering Gear
System Failure
3
1
STEERING GEAR
Q=3,425E-05

S/G Failure Leakage on S/G S/G Room

Piping Components
Failures

S/G SYSTEMS S/G PIPING S/ G RO O M CO M PO NENETS

S/G PIPING
MTTF=17520
Q=3,425E-05
Manual S/G Selenoid Valve Hydraulic Piston
Failure Failure Failure

MANUAL S/G GT332 GT333 S/GSEL ENOIDVALVES S/G HYD PISTONS

MANUAL S/G
MTTF=52560
Q=0
Hydraulic S/G S/G Pump or Selenoid Valve Selenoid Valve Hydraulic Piston Hydraulic Piston
Failure Electric Supply Failure Failure Failure Failure
Failure

S/G HYDRAUL IC SYS S/G S/ G SELENO I D VALVE G RO UP 1 S/ G SELENO I D VALVE G RO UP 2 S/G HYD PISTON 1 S/G HYD PISTON 2

S/G SELENOID S/G SELENOID S/G HYD S/G HYD

VALVE GROUP VALVE GROUP PISTON 1 PISTON 2
1 2 MTTF=52560 MTTF=26280
Hydraulic manual Hydraulic Manual Pump Failures MTTF=52560
S/G Section MTTF=26280 Q=0 Q=9,512E-05
pump failure Pump Failure BoardQ=0
Electric Q=3,805E-05
Supply Failure

S/ G HYD SYS PUM P O N BRI DG E S/ G HYD PUM P I N S/ G RO O M

S/G PUMPS S/G SEC BOARD

S/G HYD SYS S/G HYD STEERING

PUMP ON PUMP IN S/G GEAR
BRIDGE ROOM SECTION
MTTF=26280 MTTF=52560 Pump Unit Pump Unit BOARD
Q=0,0004564 Q=0 Failure Failure MTTF=26280
Q=1,903E-05

PUMP UNIT 1 PUMP UNIT 2

S/G Pump S/G Hydraulşc S/G Pump S/G Hydraulşc

Electric Motor Pump Failure Electric Motor Pump Failure
Failure Failure

S/ G PUM P ELEC M O TO R 1
S/G HYD PUMP 1 S/ G PUM P ELEC M O TO R 2
S/G HYD PUMP 2

S/G PUMP S/G HYD S/G PUMP S/G HYD

ELEC MOTOR1 PUMP1 ELEC MOTOR2 PUMP2
MTTF=52560 MTTF=52560 MTTF=26280 MTTF=52560
Q=0 Q=0 Q=0,001823 Q=0

107
 Fault Tree Diagrams
SHIP RELIABILITY

El e c tri c Power
Sy s te m Fa ilure

1
ELECTRI C PO WER SYSTEM

Q =9, 844E- 05

M ain El e c tri c a l Wirng Bo a rd s Po wer

Swi tc h b oard Fa i lure Su p p l y Fa ilure
fa i lure

M AI N SWI TCHBO ARD ELECTRI CAL WI RI NG PRI O R BO ARDS

EL EC WIRING
NETWORK
M TTF=17520
Swi tc h Fa i lure Swi tc h Fa i lure Sy n c ro n ation Q=5 ,7 0 7 E-05
Un i t Fa i lure Se c ti o n Board Em e rgency
Fa i lure Po we rSu pply
Ge n s e ts p roduce Fa i lure
n o e l e c tricity
SECBO ARDSWI TCHES
M AI N SWI TCHES SYNCRO NATI O N UNI T
SECTI O N BO ARDS BO ARD'S EM ERG ENCY SUPPLY

GENSETS M AIN SEC BOARD SYNC UNIT

SWITCHES SWITCHES M TTF=52560
M TTF=26280 M TTF=26280 Q=0
Q=1 ,9 0 3 E-05 Q=1 ,9 0 3 E-05
Se c ti o n board Se c ti o n board S/GSe c tion Ba tte ry v o ltage Wi ri n g fa ilure
e l e c tri c a l failure e l e c tri c a l failure Bo a rd El e c tric l ow
Ge n s e t p roduce Ge n s e t p roduce Su p p l y Fa ilure
n o e l e c tricity n o e l e c tricity

NAVI G ATI O NALASSETS'SECBO ARD ENG I NERO O M SECBO AR

D EM ERG ENCY BATTERI ES EM ERG ENCY WI RI NG
S/ G SEC BO ARD

GENSET 1 GENSET 2
NAVIGATIONA ENGINE ROOM STEERING EM ER EM ER SUPPL Y
L ASSETS SECTİON GEAR BATTERIES WIRINGS
SECTION BOARD SECTION M TTF=13140 M TTF=26280
BOARD M TTF=26280 BOARD Q=4 ,7 5 6 E-05 Q=9 ,5 1 3 E-06
M TTF=13140 Q=5 ,7 0 7 E-05 M TTF=26280
Q=5 ,7 0 7 E-05 Q=1 ,9 0 3 E-05
En g i n e Fa ilure Ge n e ra to rdoes El e c tri c a l Wirng En g i n e Fa ilure Ge n e ra to rdoes El e c tri c a l Wirng
n o t p ro duce Fa i lure n o t p ro duce Fa i lure
e l e c tricity e l e c tricity

GEN DIESEL 1 GENERATOR 1 G ENERATO RWI RI N

G1 GEN DIESEL 2 GENERATOR 2 G ENERATO RWI RI N
G2

Page 6 GENERATOR Pa ge 11 GENERATOR

WIRING 1 WIRING 2
M TTF=26280 M TTF=52560
Sl i p ri n g fa ilure Bru s h fa i lure No e x c i ting Q=5 ,7 0 7 E-05 Sl i p ri n g fa ilure Bru s h fa i lure No e x c i ting Q=0
c u rrent c u rrent

G ENSET SLI P RI NG 1 G ENSET BRUSHES 1 G ENSETEXCI TI NG CURRENT G ENSET SLI P RI NG 2 G ENSET BRUSHES 2 G ENSET EXCI TI NG CURRENT1

GENSET SL IP GENSET GENSET GENSET SL IP GENSET GENSET

RING1 BRUSHES1 EXCITING RING2 BRUSHES2 EXCITING
M TTF=52560 M TTF=52560 CURRENT 1 M TTF=52560 M TTF=52560 CURRENT 2
Q=0 Q=0 M TTF=52560 Q=0 Q=0 M TTF=52560
Q=0 Q=0

108
 Fault Tree Diagrams
SHIP RELIABILITY

Damage Control
System Failure

1
DAM AG E CO NTRO L SYSTEM

Q=0 ,0 0 0 2 3 6

Fire Fighting and Water-tigth Diesel Oil

Water Discharge Departments Transfer System
System Failure Failure Failure

FI REFI G HTI NG &WATERDI SCHARG ESY

S WATER- TI G TH DEPTS DOTRANSFERSYS

Pump Units Leakage on Fire Tigthness Tigthness Leakage on Transfer Pumps

Figthing System Discharge Problem on Problem on Piping System Failure
Failure System Failure
Piping Portholes Hatchways

PUMP UNITS FI REFI G THI NG SYSPI PI NG

DI SCHARG E SYSTEM
PORTHOLES HATCHWAYS DO TRANSFER SYS PI PI NG TRANSFERPUMPS

FIRE PORTHOLES HATCHWAYS DO TRANSFER

FIGHTING MTTF=10512 MTTF=13140 SYSTEM
PIPING Q=1,903E-05 Q=5,327E-05 PIPING
MTTF=13140 MTTF=17520
Fixed Water Submersible Q=0,0001141
Q=3,805E-05 Discharge Pump Failure
System Failure

GT338 GT339 FI XEDWATERDI SCHARG ESYS SUBM ERSI BLEELECTRI CALPUM P GT334 GT335

FIXED WATER SUBMERSIBLE

DISCHARGE ELECTRICAL
SYSTEM PUMP
Pump Unit Pump Unit MTTF=17520 MTTF=26280 DO Transfer Hand Pump
Failure Failure Q=9,512E-05 Q=0,001823 Pump Failure Failure

FIREPUM PUNIT 1 FIREPUM PUNIT 2 DO TRANSFER PUM P UNI T DOTRAHANDPUMP

DO TRANSFER
HAND PUMP
MTTF=26280
Electric Motor Pump Failure Electric Motor Pump Failure Electric Motor Pump Failure Q=0,0003804
Failure Failure Failure

EL EC M OTOR 1 FIRE PUMP 1 EL EC M OTOR 2 FIRE PUMP 2 DO TRA PUM P ELEC M O TO R DO TRANSFER PUM P

FIRE PUMP FIRE PUMP 1 FIRE PUMP FIRE PUMP 2 DO TRANSFER DO TRANSFER
ELEC MOTOR MTTF=17520 ELEC MOTOR MTTF=52560 PUMP PUMP
1 Q=0,004545 2 Q=0 ELECTRIC MTTF=26280
MTTF=52560 MTTF=26280 MOTOR Q=0,0009124
Q=0 Q=0,002278 MTTF=26280
Q=0,001823

109
 Fault Tree Diagrams
SHIP RELIABILITY

Engine Failure

GEN DIESEL 1

Charge air Engine alarm Water mixed into Fuel Supply Lubrication Oil Lubrication Oil Cooling Water
supply failure system failure lub oil Failure Temperature Pressure Low Temperature
High High

GENSET AIR SYS 1 GENSET AL ARM SYS1 G ENSETLUBO I LM I XEDWI THWAT

R1
E GENSET FUEL SYSTEM1 GENSET L UBOIL TEMP1 G ENSET LUB O I L SYSTEM 1 G ENSETCO O LI NG WATERSYS
M1
E
T

GENSET AIR GENSET GENSET LUB Page 7 Page 8 Page 9 Page 10

SYS1 ALARM SYS1 OIL MIXED
MTTF=52560 MTTF=26280 WITH WATER Start System
Q=0 Q=1,903E-05 1 Failure
MTTF=26280
Q=3,805E-05

GENSET START SYS1

Battery voltage Start Motor Start Switch Start System

low failure failure Wiring failure

G ENSET START BATTERI ES 1 G ENSET START M O TO R 1 G ENSET START SWI TCH 1 G ENSET START SYS WI RI NG 1

GENSET GENSET GENSET GENSET

START START START START SYS
BATTERIES 1 MOTOR 1 SWITCH 1 WIRING 1
MTTF=26280 MTTF=52560 MTTF=52560 MTTF=52560
Q=3,805E-06 Q=0 Q=0 Q=0

110
 Fault Tree Diagrams
SHIP RELIABILITY

Fuel Supply
Failure

6
GENSET FUEL SYSTEM1

Fuel Service Dublex Filters Bosch Type Fuel Some Injectors Fuel Leakage on
Pump Failure No Clogged Pump Failure do not spray fuel fuel piping
fuel at fuel filter
inlet

GENSET FUEL SRVC PUM P 1 GENSET DUBLEX FILTERS1 GENSET FUEL PUMP 1 GENSET INJECTORS 1 GENSET PIPING FUEL SYS 1

GENSET GENSET FUEL GENSET GENSET

FUELSRVCPU PUMP1 INJECTORS1 PIPING FUEL 1
MP 1 MTTF=52560 MTTF=26280 MTTF=26280
MTTF=52560 Fuel Filter Fuel Filter Q=0 Q=9,512E-05 Q=1,142E-05
Q=0 Glogged Clogged

GENSET DUBL EX FUEL FIL T A1 GENSET DUBL EX FUEL FIL T B1

GENSET GENSET
DUBLEX DUBLEX
FILTER A1 FILTER B1
MTTF=26280 MTTF=52560
Q=5,708E-06 Q=0

111
 Fault Tree Diagrams
SHIP RELIABILITY

Lubrication Oil
Temperature 8
High

6,9
GENSET LUB OIL TEMP 1

Sea water supply Lub Oil HEX Oil level is low

loss clogged

10

GENSET SEA WATER SYS 1 GENSET LUB OIL HEX 1 GENSET SUM P OIL L EVEL 1

GENSET LUB GENSET

OIL HEX1 SUMP OIL
MTTF=52560 LEVEL1
Leakage on S/W Sea water supply Q=0 MTTF=52560
Piping loss Q=0

GENSET S/W PIPING 1 GENSET S/W SUPPL Y SYS 1

GENSET S/W
PIPING 1
MTTF=26325
Q=7,597E-06 Emergency sea Main Sea Water
water supply loss System Failure

GENSET EM ERGENCYS/W SUPPLY1 GENSET S/W PUM P SUPPL Y 1

GENSET
EMER S/W
SUPPLY 1
MTTF=52560 Suction Valve S/W Pump failure
Q=0 stucked closed

GENSET S/W SUCTIONVALVE1 GENSET S/W PUMP 1

GENSET S/W GENSET S/W

SUCTION PUMP 1
VALVE 1 MTTF=26280
MTTF=52560 Q=1,903E-05
Q=0

112
 Fault Tree Diagrams
SHIP RELIABILITY

Lubrication Oil
Pressure Low

6
GENSET L UB OIL SYSTEM 1

Oil Filter clogged Lub Oil Pump Main Bearings Connecting Rod Leakage on lub Lubrication Oil Oil level is low
Failure worn Bearings worn oil piping system Temperature
High

GENSET FILTER OIL 1 GENSET L UB OIL PUM P 1 GENSET M AIN BEARINGS 1 GENSET CONRODBEARINGS1 GENSET L UB OIL PIPING SYS 1 GENSET L UB OIL TEM P 1 GENSET SUM P OIL L EVEL 1

GENSET OIL GENSET LUB GENSET MAIN GENSET CON GENSET Page 8 GENSET
FILTER 1 OIL PUMP 1 BEARINGS 1 ROD PIPING OIL 1 SUMP OIL
MTTF=52560 MTTF=52560 MTTF=52560 BEARINGS 1 MTTF=52560 LEVEL1
Q=0 Q=0 Q=0 MTTF=52560 Q=0 MTTF=52560
Q=0 Q=0

113
 Fault Tree Diagrams
SHIP RELIABILITY

10

Cooling Water
Temperature
High

6
G ENSET CO O LI NG WATER SYSTEM 1

Fresh water HEX Fresh Water Thermostat Fresh Water Sea water supply
clogged Level low failure Pump failure loss

8
G ENSET M AI N ENG F/ W HEX 1
GENSET F/W L EVEL 1 GENSET THERM OSTAT 1 GENSET F/W PUMP 1 GENSET SEAWATERSYS1

GENSET F/W GENSET F/W GENSET GENSET F/W

HEX 1 LEVEL 1 THERMOSTAT PUMP 1
MTTF=52560 MTTF=52560 1 MTTF=26280
Q=0 Q=0 MTTF=52560 Q=0,0001522 Leakage on S/W Sea water supply
Q=0 Piping loss

GENSET S/W PIPING 1 GENSET S/W SUPPLYSYS1

GENSET S/W
PIPING 1
MTTF=26325
Q=7,597E-06 Emergency sea Main Sea Water
water supply loss System Failure

G ENSET EM ERG ENCY S/ W SUPPLY 1 G ENSET S/ W PUM P SUPPLY 1

GENSET
EMER S/W
SUPPLY 1
MTTF=52560 Suction Valve S/W Pump failure
Q=0 stucked closed

G ENSET S/ W SUCTI O N VALVE 1 GENSET S/W PUMP 1

GENSET S/W GENSET S/W

SUCTION PUMP 1
VALVE 1 MTTF=26280
MTTF=52560 Q=1,903E-05
Q=0

114
 Fault Tree Diagrams
SHIP RELIABILITY

11

Engine Failure

4
GEN DIESEL 2

Charge air Engine alarm Water mixed into Fuel Supply Lubrication Oil Lubrication Oil Cooling Water Start System
supply failure system failure lub oil Failure Temperature Pressure Low Temperature Failure
High High

GENSET AIRSYS2 GENSET ALARM SYS2 G ENSETLUBO I LM I XEDWI THWA

R2
E
T G ENSET FUEL SYSTEM 2 G ENSET LUB O I L TEM P 2 G ENSET LUB O I L SYSTEM 2 G ENSETCO O LI NG WATERSY
M2
E
T
S GENSET START SYS2

GENSET AIR GENSET GENSET LUB Page 12 Page 13 Page 14 Page 15

SYS2 ALARM SYS2 OIL MIXED
MTTF=26280 MTTF=52560 WITH WATER
Q=9,513E-06 Q=0 2 Battery voltage Start Motor Start Switch Start System
MTTF=52560 low failure failure Wiring failure
Q=0

G ENSET START BATTERI ES 2 G ENSET START M O TO R 2 G ENSET START SWI TCH 2 G ENSETSTARTSYSWI RI NG 2

GENSET GENSET GENSET GENSET

START START START START SYS
BATTERIES 2 MOTOR 2 SWITCH 2 WIRING 2
MTTF=52560 MTTF=52560 MTTF=52560 MTTF=52560
Q=0 Q=0 Q=0 Q=0

115
 Fault Tree Diagrams
SHIP RELIABILITY

12

Fuel Supply
Failure

11
GENSET FUEL SYSTEM2

Fuel Service Dublex Filters Bosch Type Fuel Some Injectors Fuel Leakage on
Pump Failure No Clogged Pump Failure do not spray fuel fuel piping
fuel at fuel filter
inlet

GENSET FUEL SRVC PUM P 2 GENSET DUBLEX FILTERS2 GENSET FUEL PUMP 2 GENSET INJECTORS 2 GENSET PIPING FUEL SYS 2

GENSET GENSET FUEL GENSET GENSET

FUELSRVCPU PUMP2 INJECTORS2 PIPING FUEL 2
MP 2 MTTF=17520 MTTF=17520 MTTF=17520
MTTF=26280 Fuel Filter Fuel Filter Q=0,004093 Q=0,0001522 Q=3,044E-05
Q=7,61E-05 Glogged Clogged

GENSET DUBL EX FUEL FIL T A2 GENSET DUBL EX FUEL FIL T B2

GENSET GENSET
DUBLEX DUBLEX
FILTER A2 FILTER B2
MTTF=52560 MTTF=26280
Q=0 Q=5,708E-06

116
 Fault Tree Diagrams
SHIP RELIABILITY

Lubrication Oil
Temperature 13
High

11,14
GENSET LUB OIL TEMP 2

Sea water supply Lub Oil HEX Oil level is low

loss clogged

15

GENSET SEA WATER SYS 2 GENSET LUB OIL HEX 2 GENSET SUM P OIL L EVEL 2

GENSET LUB GENSET

OIL HEX2 SUMP OIL
MTTF=26280 LEVEL2
Leakage on S/W Sea water supply Q=7,61E-05 MTTF=52560
Piping loss Q=0

GENSET S/W PIPING 2 GENSET S/W SUPPL Y SYS 2

GENSET
PIPING OIL 2
MTTF=26280
Q=5,708E-06 Emergency sea Main Sea Water
water supply loss System Failure

GENSET EM ERGENCYS/W SUPPLY2 GENSET S/W PUM P SUPPL Y 2

GENSET
EMER S/W
SUPPLY 2
MTTF=52560 Suction Valve S/W Pump failure
Q=0 stucked closed

GENSET S/W SUCTIONVALVE2 GENSET S/W PUMP 2

GENSET S/W GENSET S/W

SUCTION PUMP 2
VALVE 2 MTTF=26280
MTTF=52560 Q=1,903E-05
Q=0

117
 Fault Tree Diagrams
SHIP RELIABILITY

14

Lubrication Oil
Pressure Low

11
GENSET L UB OIL SYSTEM 2

Oil Filter clogged Lub Oil Pump Main Bearings Connecting Rod Leakage on lub Lubrication Oil Oil level is low
Failure worn Bearings worn oil piping system Temperature
High

GENSET FILTER OIL 2 GENSET L UB OIL PUM P 2 GENSET M AIN BEARINGS 2 GENSET CONRODBEARINGS2 GENSET L UB OIL PIPING SYS 2 GENSET L UB OIL TEM P 2 GENSET SUM P OIL L EVEL 2

GENSET OIL GENSET LUB GENSET MAIN GENSET CON GENSET Page 13 GENSET
FILTER 2 OIL PUMP 2 BEARINGS 2 ROD PIPING OIL 2 SUMP OIL
MTTF=52560 MTTF=52560 MTTF=52560 BEARINGS 2 MTTF=26280 LEVEL2
Q=0 Q=0 Q=0 MTTF=52560 Q=5,708E-06 MTTF=52560
Q=0 Q=0

118
 Fault Tree Diagrams
SHIP RELIABILITY

15

Cooling Water
Temperature
High

11
G ENSET CO O LI NG WATER SYSTEM 2

Fresh water HEX Fresh Water Thermostat Fresh Water Sea water supply
clogged Level low failure Pump failure loss

13
G ENSET M AI N ENG F/ W HEX 2
GENSET F/W L EVEL 2 GENSET THERM OSTAT 2 GENSET F/W PUMP 2 GENSET SEAWATERSYS2

GENSET F/W GENSET F/W GENSET GENSET F/W

HEX 2 LEVEL 2 THERMOSTAT PUMP 2
MTTF=26280 MTTF=52560 2 MTTF=17520
Q=7,61E-05 Q=0 MTTF=26280 Q=0,004093 Leakage on S/W Sea water supply
Q=1,522E-05 Piping loss

GENSET S/W PIPING 2 GENSET S/W SUPPLYSYS2

GENSET
PIPING OIL 2
MTTF=26280
Q=5,708E-06 Emergency sea Main Sea Water
water supply loss System Failure

G ENSET EM ERG ENCY S/ W SUPPLY 2 G ENSET S/ W PUM P SUPPLY 2

GENSET
EMER S/W
SUPPLY 2
MTTF=52560 Suction Valve S/W Pump failure
Q=0 stucked closed

G ENSET S/ W SUCTI O N VALVE 2 GENSET S/W PUMP 2

GENSET S/W GENSET S/W

SUCTION PUMP 2
VALVE 2 MTTF=26280
MTTF=52560 Q=1,903E-05
Q=0

119
 Fault Tree Diagrams
SHIP RELIABILITY

16

Main Engine
No:1 Failure

2
M AIN ENGINE NO:1

Alarm System Water Mixed into

Fuel Supply Lubrication Oil Cooling Water Lubrication Oil Charge Air Failure Lubrication Oil
Failure Pressure Low Temperature Temperature Supply Failure
High High

M AI N ENG ALARM SYS 1 M AI NENG WATERM I XEDI NTO LU

BOIL
1
M AI N ENG I NE FUEL SYSTEM 1 M AI NENG I NELUBO I LSYSTEM 1 M AI NENG I NECO O LI NG WATERSY
M1
E
T
S M AI N ENG LUB O I L TEM P 1
M AI N ENG CHARG E AI R SYS 1

MAIN ENG MAIN ENG LUB

Page 18 Page 19 Page 20 Page 21 ALARM SYS1 OIL MIXED
MTTF=17520 WATER 1
Start System Q=3,805E-05 MTTF=26280
Air filter clogged Supercharger Failure
Q=5,707E-05
failure

M AINENGSTART SYS1

M AI NENG CHARG EAI RFI LTER1 M AI N ENG SUPERCHARG ER 1

MAIN ENG AIR MAIN ENG

FILTER1 SUPERCHARG
MTTF=52560 ER1 Battery voltage Start Motor Start Switch Start System
Q=0 MTTF=26280 low failure failure Wiring failure
Q=0,001823

M AI N ENG START BATTERI ES 1 M AI N ENG START M O TO R 1 M AI N ENG START SWI TCH 1 M AI NENG STARTSYSWI RI NG 1

MAIN ENG MAIN ENG MAIN ENG MAIN ENG

START START START START SYS
BATTERIES1 MOTOR 1 SWITCH 1 WIRING 1
MTTF=52560 MTTF=52560 MTTF=52560 MTTF=26280
Q=0 Q=0 Q=0 Q=7,61E-06

120
 Fault Tree Diagrams
SHIP RELIABILITY

17

Main Engine
No:2 Failure

2
M AIN ENGINE NO:2

Fuel Supply Lubrication Oil Cooling Water Lubrication Oil Charge Air Alarm System Water Mixed into
Failure Pressure Low Temperature Temperature Supply Failure Failure Lubrication Oil
High High

M AI N ENG I NE FUEL SYSTEM 2 M AI NENG I NELUBO I LSYSTE

M2 M AI NENG I NECO O LI NG WATERSYS
M2
E
T M AI N ENG LUB O I L TEM P 2 M AI N ENG CHARG E AI R SYS 2 M AI N ENG ALARM SYS 2 M AI NENG WATERM I XEDI NTO LUBOIL
2

Start System
Page 22 Page 23 Page 24 Page 25 MAIN ENG MAIN ENG LUB
Failure
ALARM SYS2 OIL MIXED
MTTF=10512 WATER 2
Air filter clogged Supercharger Q=6,468E-05 MTTF=52560
Q=0
failure
M AI N ENG START SYS 2

M AI NENG CHARG EAI RFI LTE

R2 M AI N ENG SUPERCHARG ER 2

Battery voltage Start Motor Start Switch Start System

MAIN ENG AIR MAIN ENG low failure failure Wiring failure
FILTER2 SUPERCHARG
MTTF=26280 ER2
Q=3,805E-06 MTTF=52560
Q=0
M AI NENG STARTBATTERI ES2 M AI N ENG START M O TO R 2 M AI N ENG START SWI TCH 2 M AI NENG STARTSYSWI RIN
G2

MAIN ENG MAIN ENG MAIN ENG MAIN ENG

START START START START SYS
BATTERIES2 MOTOR 2 SWITCH 2 WIRING 2
MTTF=52560 MTTF=26280 MTTF=26280 MTTF=52560
Q=0 Q=0,0004564 Q=5,708E-06 Q=0

121
 Fault Tree Diagrams
SHIP RELIABILITY

18

Fuel Supply
Failure

16
M AIN ENGINE FUEL SYSTEM 1

Fuel Service Dublex Filters Bosch Type Fuel Some Injectors Fuel Leakage on
Pump Failure No Clogged Pump Failure do not spray fuel fuel piping
fuel at fuel filter
inlet

M AIN ENG FUEL SRVC PUM P 1 DUBLEX FILTERS MAIN ENG FUEL PUMP 1 MAIN ENG ıNJECTORS 1 M AIN ENG PIPING FUEL SYS 1

MAIN ENG MAIN ENG MAIN ENG MAIN ENG

FUEL SRVC FUEL PUMP1 INJECTORS1 PIPING FUEL
PUMP1 MTTF=52560 MTTF=17520 SYS1
MTTF=26280 Fuel Filter Fuel Filter Q=0 Q=9,512E-05 MTTF=52560
Q=0,0002283 Glogged Clogged Q=0

M AIN ENG DUBL EX FUEL FIL T A1 MAIN DUBLEX FUEL FILT B1

MAIN ENG MAIN ENG

DUBLEX DUBLEX FUEL
FILTER A1 FILT B1
MTTF=26280 MTTF=26280
Q=5,708E-06 Q=5,708E-06

122
 Fault Tree Diagrams
SHIP RELIABILITY

19

Lubrication Oil
Pressure Low

16
M AINENGINEL UBOIL SYSTEM1

Oil level is low Oil Filter clogged Lub Oil Pump Main Bearings Lubrication Oil Connecting Rod Leakage on lub
Failure worn Temperature Bearings worn oil piping system
High

M AINENGSUM POIL L EVEL 1 MAIN ENG FILTER OIL 1 M AIN ENG L UB OIL PUM P 1 M AIN ENG M AIN BEARINGS 1 M AIN ENG L UB OIL TEM P 1 M AINENGCONRODBEARINGS1 M AINENGL UBOIL PIPINGSYS1

MAIN ENG MAIN ENG MAIN ENG LUB MAIN ENG Page 21 MAIN ENG MAIN ENG
SUMP OIL FILTER OIL1 OIL PUMP1 MAIN CON ROD PIPING OIL1
LEVEL1 MTTF=52560 MTTF=52560 BEARINGS1 BEARINGS1 MTTF=52560
MTTF=52560 Q=0 Q=0 MTTF=52560 MTTF=52560 Q=0
Q=0 Q=0 Q=0

123
 Fault Tree Diagrams
SHIP RELIABILITY

20

Cooling Water
Temperature
High

16
M AI NENG I NECO O LI NG WATERSYST
M1
E

Sea water supply Fresh water HEX Fresh Water Thermostat Fresh Water
loss clogged Level low failure Pump failure

21

M AINENGSEAWATERSYS1 MAIN ENG F/W HEX 1 M AIN ENG F/W L EVEL 1 M AIN ENG THERM OSTAT 1 M AIN ENG F/W PUM P 1

MAIN ENG F/W MAIN ENG F/W MAIN ENG MAIN ENG F/W
HEX1 LEVEL1 THERMOSTAT PUMP1
MTTF=52560 MTTF=52560 1 MTTF=52560
Leakage on S/W Sea water supply Q=0 Q=0 MTTF=52560 Q=0
Piping loss Q=0

M AIN ENG S/W PIPING 1 M AINENGS/W SUPPLYSYS

MAIN ENG S/W

PIPING1
MTTF=52560
Q=0 Emergency sea Main Sea Water
water supply loss System Failure

EM ERGENCY S/W SUPPL Y M AI N ENG S/ W PUM P SUPPLY

MAIN ENG
EMER S/W
SUPPLY1
MTTF=52560 Suction Valve S/W Pump failure
Q=0 stucked closed

M AI N ENG S/ W SUCTI O N VALVE 1 M AIN ENG S/W PUM P 1

MAIN ENG S/W MAIN ENG S/W

SUCTION PUMP1
VALVE1 MTTF=52560
MTTF=52560 Q=0
Q=0

124
 Fault Tree Diagrams
SHIP RELIABILITY

Lubrication Oil
Temperature 21
High

16,19
MAIN ENG LUB OIL TEMP 1

Sea water supply Lub Oil HEX Oil level is low

loss clogged

20
M AIN ENG SEA WATER SYS 1 MAIN ENG LUB OIL HEX 1 M AIN ENG SUM P OIL L EVEL 1

MAIN ENG LUB MAIN ENG

OIL HEX1 SUMP OIL
MTTF=52560 LEVEL1
Leakage on S/W Sea water supply Q=0 MTTF=52560
Piping loss Q=0

MAIN ENG S/W PIPING 1 M AIN ENG S/W SUPPL Y SYS

MAIN ENG S/W

PIPING1
MTTF=52560
Q=0 Emergency sea Main Sea Water
water supply loss System Failure

EMERGENCY S/W SUPPLY M AIN ENG S/W PUM P SUPPL Y

MAIN ENG
EMER S/W
SUPPLY1
MTTF=52560 Suction Valve S/W Pump failure
Q=0 stucked closed

M AINENGS/W SUCTIONVALVE1 MAIN ENG S/W PUMP 1

MAIN ENG S/W MAIN ENG S/W

SUCTION PUMP1
VALVE1 MTTF=52560
MTTF=52560 Q=0
Q=0

125
 Fault Tree Diagrams
SHIP RELIABILITY

22

Fuel Supply
Failure

17
M AIN ENGINE FUEL SYSTEM 2

Fuel Service Dublex Filters Bosch Type Fuel Some Injectors Fuel Leakage on
Pump Failure No Clogged Pump Failure do not spray fuel fuel piping
fuel at fuel filter
inlet

M AIN ENG FUEL SRVC PUM P 2 DUBLEX FILTERS1 MAIN ENG FUEL PUMP 2 MAIN ENG ıNJECTORS 2 M AIN ENG PIPING FUEL SYS 2

MAIN ENG MAIN ENG MAIN ENG MAIN ENG

FUELSRVC FUEL PUMP2 INJECTORS2 PIPING FUEL
PUMP2 MTTF=26280 MTTF=26280 SYS2
MTTF=52560 Fuel Filter Fuel Filter Q=0,0009124 Q=3,805E-05 MTTF=26280
Q=0 Glogged Clogged Q=1,522E-05

M AIN ENG DUBL EX FUEL FIL T A2 MAIN DUBLEX FUEL FILT B2

MAIN ENG MAIN ENG

DUBLEX FUEL DUBLEX FUEL
FILT A2 FILT B2
MTTF=52560 MTTF=26280
Q=0 Q=5,708E-06

126
 Fault Tree Diagrams
SHIP RELIABILITY

23

Lubrication Oil
Pressure Low

17
M AINENGINEL UBOIL SYSTEM2

Oil level is low Oil Filter clogged Lub Oil Pump Main Bearings Lubrication Oil Connecting Rod Leakage on lub
Failure worn Temperature Bearings worn oil piping system
High

M AINENGSUM POIL L EVEL 2 MAIN ENG FILTER OIL 2 M AIN ENG L UB OIL PUM P 2 M AIN ENG M AIN BEARINGS 2 M AIN ENG L UB OIL TEM P 2 M AINENGCONRODBEARINGS2 M AINENGL UBOIL PIPINGSYS2

MAIN ENG MAIN ENG MAIN ENG LUB MAIN ENG Page 25 MAIN ENG MAIN ENG
SUMP OIL FILTER OIL2 OIL PUMP2 MAIN CON ROD PIPING OIL2
LEVEL2 MTTF=52560 MTTF=52560 BEARINGS2 BEARINGS2 MTTF=52560
MTTF=52560 Q=0 Q=0 MTTF=52560 MTTF=52560 Q=0
Q=0 Q=0 Q=0

127
 Fault Tree Diagrams
SHIP RELIABILITY

24

Cooling Water
Temperature
High

17
M AI NENG I NECO O LI NG WATERSYST
M2
E

Sea water supply Fresh water HEX Fresh Water Thermostat Fresh Water
loss clogged Level low failure Pump failure

25

M AINENGSEAWATERSYS2 MAIN ENG F/W HEX 2 M AIN ENG F/W L EVEL 2 M AIN ENG THERM OSTAT 2 M AIN ENG F/W PUM P 2

MAIN ENG F/W MAIN ENG F/W MAIN ENG MAIN ENG F/W
HEX2 LEVEL2 THERMOSTAT PUMP2
MTTF=26280 MTTF=52560 2 MTTF=26280
Leakage on S/W Sea water supply Q=5,707E-05 Q=0 MTTF=52560 Q=0,0001522
Piping loss Q=0

M AIN ENG S/W PIPING 2 M AINENGS/W SUPPLYSYS1

MAIN ENG S/W

PIPING2
MTTF=17520
Q=1,522E-05 Emergency sea Main Sea Water
water supply loss System Failure

EM ERGENCYS/W SUPPLY1 M AI N ENG S/ W PUM P SUPPLY1

MAIN ENG
EMER S/W
SUPPLY2
MTTF=52560 Suction Valve S/W Pump failure
Q=0 stucked closed

M AI N ENG S/ W SUCTI O N VALVE 2 M AIN ENG S/W PUM P 2

MAIN ENG S/W MAIN ENG S/W

SUCTION PUMP2
VALVE2 MTTF=52560
MTTF=26280 Q=0
Q=1,522E-05

128
 Fault Tree Diagrams
SHIP RELIABILITY

Lubrication Oil
Temperature 25
High

17,23
MAIN ENG LUB OIL TEMP 2

Sea water supply Lub Oil HEX Oil level is low

loss clogged

24
M AIN ENG SEA WATER SYS 2 MAIN ENG LUB OIL HEX 2 M AIN ENG SUM P OIL L EVEL 2

MAIN ENG LUB MAIN ENG

OIL HEX2 SUMP OIL
MTTF=52560 LEVEL2
Leakage on S/W Sea water supply Q=0 MTTF=52560
Piping loss Q=0

MAIN ENG S/W PIPING 2 M AIN ENG S/W SUPPL Y SYS1

MAIN ENG S/W

PIPING2
MTTF=17520
Q=1,522E-05 Emergency sea Main Sea Water
water supply loss System Failure

EM ERGENCY S/W SUPPL Y1 M AIN ENG S/W PUM P SUPPL Y1

MAIN ENG
EMER S/W
SUPPLY2
MTTF=52560 Suction Valve S/W Pump failure
Q=0 stucked closed

M AINENGS/W SUCTIONVALVE2 MAIN ENG S/W PUMP 2

MAIN ENG S/W MAIN ENG S/W

SUCTION PUMP2
VALVE2 MTTF=52560
MTTF=26280 Q=0
Q=1,522E-05

129
130
CURRICULUM VITAE

Name Surname: Oğuz AKKAYA

Place and Date of Birth: İstanbul-1972

Address: Deniz Harp Okulu K.lığı Dekanlık Tuzla-İstanbul

E-Mail: oguzakkaya@gmail.com

B.Sc.: Turkish Naval Academy Mechanical Engineering

Professional Experience and Rewards:

1994-2005 : Second Engineer and Chief Engineer posts on Turkish Navy

2005-2006 : Maintenance Planning Officer in İstanbul Shipyard

2006-2008: Company Commander in Turkish Naval Academy

2008-2012 : Marine Engineering Lecturer in Turkish Naval Academy

List of Publications and Patents:

PUBLICATIONS/PRESENTATIONS ON THE THESIS

Akkaya O., SÖĞÜT O.S., 2012: Hata Ağacı Analizi İle Standby Sistemlerin
Gemi Kullanılabilirliği Üzerine Etkisinin İncelenmesi. Gemi İnşaatı ve Deniz
Teknolojisi Teknik Kongresi, Aralık 13-14, 2012 İstanbul, Türkiye.

131