Chap 1 Aircraft Maintenance Introduction
Chap 1 Aircraft Maintenance Introduction
Chap 1 Aircraft Maintenance Introduction
General definition
Maintenance cost is broadly defined as the sum of
incurred labour, material costs and various overheads otherwise known as indirect maintenance costs. The labour is normally a process time controlled and productivity related where certain tools such as lean processes or Six sigma can be employed to enhance productivity and consequently improve consumed labour. The material element is dependant on negotiated suppliers contracts and products reliability programs.
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worldwide airlines direct operating costs. These costs are growing in view of introduction of new more
expensive
material,
highly
sophisticated
repair
schemes especially those associated with structural parts and core Engine parts, and increasing labour costs.
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factors to the maintenance costs such as Aircraft utilisation, Environment and Age. Furthermore,
influence
product
support
and
as Controllable and Non Controllable Costs. The controllable cost element is further split into
elements of airlines maintenance costs and contain such costs where practicable through introduction of
pressure in light of the current downturn reducing demand especially on premium cabin, hence the
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pertain to Direct and Indirect Maintenance. Per IATA, Direct Maintenance comprises the following, by Cost segment:
- Airframe, Engines and component maintenance. And
by cost element: Labour, Material and Outside repair Where, Indirect Maintenance includes the Overheads
costs.
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follows: - Direct Maintenance Cost is, the direct airframe and Engine maintenance which consist of the labour and material required to perform service, repair, modification, restoration, inspection, test, and troubleshooting tasks during on-airplane and shop maintenance activities.
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supervision, maintenance training, maintenance planning, unallocated labour costs, rentals and Utilities.
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Direct Maintenance Cost (DMC) and Indirect Maintenance Cost (IMC). The breakdown of these
costs is:
2.1 Direct maintenance costs 2.2 Indirect maintenance costs
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2.1.1
ON aircraft maintenance
during the scheduled aircraft checks as defined by the Manufacturers MPD documents where an extensive
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dedicated to tests, inspection, minor airframe corrections and components removals which are due for routine maintenance. IATA as shown in Figure (1) below refer to this maintenance category as 1st Level Maintenance costs segments that include Airframe and Engines Labour, materials and subcontracted work.
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1- Direct Maintenance Cost Airframe / Engine Component / Overview On Aircraft Off Aircraft
- Labor - Material - Subcontracted - Labor - Material - Subcontracted - Labor - Material - Subcontracted
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Life cycle cost Total operating cost Direct operating cost Financial Insurance Crew
AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
Disposal cost
Indirect operating cost Passenger services Marketing and sales Indirect maintenance cost Other
Direct maintenance cost Landing & Navigation fees Fuel and oil Cash operating cost
Aircraft Maintenance Costs - Guest Lecture - Cranfield University - March 2009 - CSMAM - Ref. D09005085 Issue 1
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and components in either In house or outsourced overhaul shops as these costs comprise expended labour, material, testing and modifications.
The above two categories are generally split as per below
percentages.
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follows:
1. Aircraft Transit checks- this is a normal minor check that
occurs every flight where walk around is conducted by the Engineers to detect any obvious damage and/or discrepancy which my obstruct aircraft despatch or serviceability for further flights. Also aircraft Log books will be reviewed to clear or defer all recorded snags.
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more extensive hours are expended in general visual inspections and overall Aircraft condition. Minor
modification (Engineering Orders) can be conducted and additional defects clearances which require extended times can be accomplished during this check.
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occurred almost every three months or 500 flight hours with various tasks scheduled for accomplishment. Few access panels, Engine cowlings and other doors will be opened to perform certain visual inspections and rectifications.
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for an extended time where many routine MPD tasks will be carried out. As majority of access panels are opened, a detailed visual inspection will be carried out on airframes linkages, structural fittings and main systems (such as oil, hydraulic and fuel) functional or leak checks and major components defect rectification. The interior cabin such as seats will be removed fro refurbishment. Galleys and toils will receive servicing and repairs.
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call it. The aircraft will undergo a detailed visual inspection almost in every area including main structure where a NDT and application of special die pent rants will be carried out to detect possible skin cracks. Within the cabin the primary structural parts removed for corrosion
as follows: a) Engine Repair and Overhaul Maintenance during aircraft operations, The Engines are the most stressed items where every time the aircraft takes off, Engines parts rotate at a very high speed with thrust causing certain wear to such parts at an accelerated pace. Engine internal parts especially turbine and combustion chambers are manufactured from special materials in order to withstand the high temperatures and pressure put on the engine during operations.
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and that is the reason where majority of airlines outsource engine maintenance to OEMs/MROs to alleviate the burden off airlines from investment in development of such highly sophisticated overhaul shops with special required repairs. Normally the Engine initial shop visits expenses from Aircraft induction to maturity is relatively less expensive than aging Engine maintenance as main LLP parts requires replacement then and such parts impose a high cost to the Engine Maintenance.
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In general terms, the difference between engine and airframe maintenance is that Engine material costs will exceed 80% of the total maintenance while airframe maintenance will equally share labour and material by 50/50%. The Engine performance maintenance costs optimisation is measured by the time it stays on wing as achieved by the
Replacements
This maintenance includes normal scheduled and unscheduled
components repairs to restore its serviceable condition. The parts are often categorised into rotables, repairable and expendables whereby a multiple number of repairs/resets is possible to rotables parts and considered as assets for the airline. The maintenance costs associated with this part depend significantly on whether these can be repaired In house or outsourced. This decision highly depends on two factors, the Turn around time and the Warranty aspect.
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sensible to despatch such components for repairs outside under warranty without spending much hassle to develop such capability and waste Engineers energy on warranted
components especially during the initial five years from Aircraft induction. There are occasions where rotables or repairable parts are scrapped due to economic conditions BER ,i.e. Where the Repair cost exceeds the 65% threshold of the unit cost
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cost is defined as the sum of all labour and material costs for support services which add to the total maintenance of the aircraft. The elements of IMC include the overhead costs of but not limited to, Facilities, Stores, Equipment, administration, Engineering technical services, Materials management and Engg training.
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together with organisational structure and the level of In/outsourcing plus work efficiencies.
Therefore The IMC costs fall within the category of
controllable airline maintenance costs but this factor cannot be controlled nor quantified by Aircraft
manufacturers.
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especially in the tech records, planning and materials management, drastically reduce the labour requirement and size of these support services departments and
The ideal tool for this exercise would be Six Sigma which
looks at the work environment to analyse the adopted processes, then propose solutions for the purpose of working smarter and cut inefficiencies (Turner 2005).
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Cash Airplane Related Operating Cost (CAROC) Fuel Cockpit crew Cabin crew Maintenance Landing Navigation Ground handling
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Ownership Cost Depreciation Financing (airplane and introductory investment) Operating lease cost Hull insurance
Cargo Related 25% Cost Handling Commissions Reservations and sales Advertising
System Related Cost Airplane general and administrative Passenger general and administrative Cargo general and administrative
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Food In flight services Handling Baggage handling Commissions Reservations and sales Aircraft Maintenance Module Advertising