PART- 66

COURSEWARE GAS TURBINE ENGINE

MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST EXHAUST

Table of contents

Study and Operation

Pedagogical guide

27 May 2020

1
 PART- 66
COURSEWARE
TABLE OF CONTENTS
MODULE 15

GAS TURBINE
ENGINE

B1 category
CHAPTER 1 - CONSTRUCTIONAL FEATURES AND PRINCIPLES OF OPERATION
Lesson 07
EXHAUST S/C: Location
S/C: Function

CHAPTER 2 - CONVERGENT, DIVERGENT AND VARIABLE AREA NOZZLES

CHAPTER 3 - ENGINE NOISE REDUCTION

Table of contents

Study and Operation CHAPTER 4 - THRUST REVERSERS

Pedagogical guide S/C: Function
S/C: Location
S/C: Principle
S/C: Turbo-propellers

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CONSTRUCTIONAL FEATURES AND PRINCIPLES OF
COURSEWARE OPERATION
MODULE 15
Location
GAS TURBINE
ENGINE
In a single flow turbojet, the exhaust duct is an element located within the engine
B1 category behind the turbine and by which the gas stream, having undergone the engine
thermodynamic cycle, is ejected
Lesson 07
EXHAUST In the case of a dual-flow turbojet, the hot flow exhaust duct is positioned on the
turbine outlet as on a single flow engine; the cold flow exhaust duct is located
behind the fan.

Table of contents

Study and Operation

Pedagogical guide

27 May 2020

3
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COURSEWARE OPERATION
MODULE 15
Location
GAS TURBINE
ENGINE
The stations associated with the exhaust ducts of a turbojet:
B1 category
 The stations associated with the exhaust ducts of a turbojet :
Lesson 07
EXHAUST - For a single flow turbojet:
station 4: exhaust duct inlet
station 5: exhaust duct outlet

Table of contents

Study and Operation

Pedagogical guide

27 May 2020

4
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CONSTRUCTIONAL FEATURES AND PRINCIPLES OF
COURSEWARE OPERATION
MODULE 15
Location
GAS TURBINE
ENGINE
The stations associated with the exhaust ducts of a turbojet:
B1 category
- For a dual flow turbojet:
Lesson 07  
EXHAUST Hot flow (or primary flow): Cold flow (or secondary flow):
station 5: exhaust duct inlet station  15: exhaust duct inlet
station 6: exhaust duct outlet station 18: exhaust duct outlet
 

Table of contents

Study and Operation

Pedagogical guide

27 May 2020

5
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CONSTRUCTIONAL FEATURES AND PRINCIPLES OF
COURSEWARE OPERATION
MODULE 15
Function
GAS TURBINE
ENGINE
The exhaust duct’s function is to convert post-turbine gas energy into kinetic
B1 category energy.

Lesson 07  This transformation is an expansion;

EXHAUST
- it is obtained by the shape (convergent in general) of the exhaust
duct.

- It involves an acceleration of gases.

Table of contents  This acceleration generates a thrust force.

Study and Operation - It can be the main thrust of the engine (single flow engines)
Pedagogical guide - or a secondary thrust known as "residual thrust" (double flow
engine).

27 May 2020

6
 PART- 66
CONSTRUCTIONAL FEATURES AND PRINCIPLES OF
COURSEWARE OPERATION
MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide

27 May 2020 Function

7
 PART- 66
CONSTRUCTIONAL FEATURES AND PRINCIPLES OF
COURSEWARE OPERATION
MODULE 15
Construction
GAS TURBINE
ENGINE
Joining line.
B1 category
 It comprises an external casing. Inside, a cone (taper) is fixed by
Lesson 07 struts.
EXHAUST
 Its role is to channel the hot gases leaving the turbine and to transform
their annular flow into circular flow.

The taper.

Table of contents  Its role is to streamline the rear face of the turbine.

Study and Operation  It can support the rear bearing of the turbine.
Pedagogical guide Struts.

 The number of struts is variable, depending on the type of engine.

 They convey the gas flow in an axial direction.

27 May 2020
 Struts are hollow and can be thus used, due to fresh air circulating
inside, to cool the rear face of the turbine or to pressurize the turbine
8
bearing.
.
 PART- 66
CONSTRUCTIONAL FEATURES AND PRINCIPLES OF
COURSEWARE OPERATION
MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide

Joining line
27 May 2020

9
 PART- 66
CONSTRUCTIONAL FEATURES AND PRINCIPLES OF
COURSEWARE OPERATION
MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide

Taper

27 May 2020

10
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CONSTRUCTIONAL FEATURES AND PRINCIPLES OF
COURSEWARE OPERATION
MODULE 15
Construction
GAS TURBINE
ENGINE
Struts.
B1 category
 The number of struts is variable, depending on the type of engine.
Lesson 07 They convey the gas flow in an axial direction.
EXHAUST
 Struts are hollow and can be thus used, due to fresh air circulating
inside, to cool the rear face of the turbine or to pressurize the turbine
bearing.

Tail pipe.
Table of contents
 It is a cylindrical conduit intended to ensure the connection between
Study and Operation the joining line and exhaust nozzle.
Pedagogical guide  Note that it is optional, depending on how the engine is installed in the
airframe or in the nacelle.

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11
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CONSTRUCTIONAL FEATURES AND PRINCIPLES OF
COURSEWARE OPERATION
MODULE 15
Construction
GAS TURBINE
ENGINE
Nozzle.
B1 category
 The nozzle enables expansion of gases leaving the turbine to obtain
Lesson 07 maximum kinetic energy.
EXHAUST
 For a given subsonic speed of gases, the expansion nozzle is
convergent in shape.

 For a given supersonic speed of gases, the nozzle is convergent-

divergent in shape.
Table of contents

Study and Operation

Pedagogical guide

27 May 2020

12
 PART- 66
CONSTRUCTIONAL FEATURES AND PRINCIPLES OF
COURSEWARE OPERATION
MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide
Dual flow turbojet

27 May 2020

13
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CONSTRUCTIONAL FEATURES AND PRINCIPLES OF
COURSEWARE OPERATION
MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide Fixed area convergent nozzle : Mixed flow bi-pass turbojet

27 May 2020

14
 PART- 66
CONSTRUCTIONAL FEATURES AND PRINCIPLES OF
COURSEWARE OPERATION
MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Variable outlet section convergent nozzle : Eyelids
Pedagogical guide

27 May 2020

15
 PART- 66
CONSTRUCTIONAL FEATURES AND PRINCIPLES OF
COURSEWARE OPERATION
MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide
Variable outlet section convergent nozzle : Device with multiple flaps

27 May 2020

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CONSTRUCTIONAL FEATURES AND PRINCIPLES OF
COURSEWARE OPERATION
MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide Primary nozzle, convergent, multi-tab nozzle

27 May 2020

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CONSTRUCTIONAL FEATURES AND PRINCIPLES OF
COURSEWARE OPERATION
MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide Secondary nozzle, eyelids nozzle

27 May 2020

18
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CONSTRUCTIONAL FEATURES AND PRINCIPLES OF
COURSEWARE OPERATION
MODULE 15
Materials
GAS TURBINE
ENGINE
Tail pipe.
B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide

27 May 2020

19
 PART- 66
CONSTRUCTIONAL FEATURES AND PRINCIPLES OF
COURSEWARE OPERATION
MODULE 15
Materials
GAS TURBINE
ENGINE
Exhaust Pipe.
B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide

27 May 2020

20
 PART- 66
CONVERGENT, DIVERGENT AND VARIABLE AREA
COURSEWARE NOZZLES
MODULE 15
Introduction
GAS TURBINE
ENGINE
An exhaust duct is composed mainly:
B1 category
 of a joining line, including an outer jacket and a cone, the function of
Lesson 07 which is to assure the continuity of gas flow leaving the turbine,
EXHAUST
 of a tail pipe, ensuring the connection between the joining line and the
nozzle.

- The tail pipe is optional.

Table of contents - Its installation depends on how the engine is placed in the frame.

Study and Operation  of a nozzle of fixed or variable exhaust area, intended to expand and
accelerate gases.
Pedagogical guide
Nozzle architecture can vary sharply, and is classified in two groups:

 fixed convergent area ducts, found on most commercial aircraft

engines,
27 May 2020
 variable area ducts (convergent or convergent-divergent), found on
engines equipped with exhaust reheaters (Concorde or fighter
21
aircraft).
 PART- 66
CONVERGENT, DIVERGENT AND VARIABLE AREA
COURSEWARE NOZZLES
MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Exhaust duct
Pedagogical guide

27 May 2020

22
 PART- 66
CONVERGENT, DIVERGENT AND VARIABLE AREA
COURSEWARE NOZZLES
MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Nozzle types
Pedagogical guide

27 May 2020

23
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CONVERGENT, DIVERGENT AND VARIABLE AREA
COURSEWARE NOZZLES
MODULE 15
Fixed convergent area nozzle
GAS TURBINE
ENGINE
Single flow turbojet.
B1 category
 On this type of turbojet the exhaust duct is single. It is composed
Lesson 07 mainly:
EXHAUST
- of an exhaust cone, including two parts: a casing and an internal
cone.

The casing is directly attached to the turbine case. Its shape is

convergent.
Table of contents
The internal cone’s function is to adapt the annular section of the
Study and Operation flow in the turbine outlet in circular section.
Pedagogical guide
The internal cone is linked to the casing by struts which rectify the
flow.

- of a duct. On some engines, the duct precedes a tail pipe.

The duct is a convergent channel in which the expansion of hot

27 May 2020
gases produces their acceleration.

24
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CONVERGENT, DIVERGENT AND VARIABLE AREA
COURSEWARE NOZZLES
MODULE 15
Fixed convergent area nozzle
GAS TURBINE
ENGINE
Dual flow turbojet.
B1 category
 Double flow turbojets have two ducts. Both flows may be separate:
Lesson 07
EXHAUST - The exhaust duct containing hot flow enables the expansion
and the acceleration of the gas stream in the same way as in
single flow turbojets.

This acceleration, however, represents only one small part of the

turbofan’s thrust (about 20% on takeoff), and is called residual
Table of contents thrust.

Study and Operation - The exhaust duct containing cold flow makes it possible to
accelerate the gas stream, which is the main source of a
Pedagogical guide
turbofan’s thrust. It is of convergent shape and consists of two
partitions.

The internal partition is the casing surrounding hot parts of the gas
generator.
27 May 2020
The external partition constitutes the rear part of the engine
nacelle. It usually features a thrust reverser.
25
 PART- 66
CONVERGENT, DIVERGENT AND VARIABLE AREA
COURSEWARE NOZZLES
MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Fixed convergent area nozzle
Pedagogical guide

27 May 2020

26
 PART- 66
CONVERGENT, DIVERGENT AND VARIABLE AREA
COURSEWARE NOZZLES
MODULE 15
Fixed convergent area nozzle
GAS TURBINE
ENGINE
Variable ejector nozzle.
B1 category
 Engines equipped with variable area nozzles adjust more easily to
Lesson 07 their flight envelopes (as broad as possible for fighters).
EXHAUST
 Moreover, engines using re-heaters must be equipped with such
nozzles in order to compensate for the increase in mass flow rate.

 Variable ejector nozzles are classified in two groups: those with a

convergent section and those with a convergent – divergent
Table of contents section

Study and Operation - Convergent shapes limit gas exhaust velocities to Mach 1 (in
nozzle throat)..
Pedagogical guide
- To continue accelerating gases (assuming they still have energy)
and reach supersonic exhaust velocities, convergent nozzles must
be prolonged with a divergent duct.

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 PART- 66
CONVERGENT, DIVERGENT AND VARIABLE AREA
COURSEWARE NOZZLES
MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide

27 May 2020 Variable ejector nozzle

28
 PART- 66
CONVERGENT, DIVERGENT AND VARIABLE AREA
COURSEWARE NOZZLES
MODULE 15
Study of convergent jet nozzles
GAS TURBINE
ENGINE
Fixed exhaust convergent area nozzle.
B1 category
 Space upstream meets the conditions of pressure, temperature, and
Lesson 07 velocity in the turbine outlet.
EXHAUST
 The downstream space meets conditions of pressure and temperature
characteristic of the atmosphere.

Pt 5 = pressure turbine outlet and nozzle inlet

Tt 5 = temperature turbine outlet and nozzle inlet
Table of contents P 0 = atmospheric pressure
T 0 = atmospheric temperature
Study and Operation
 When pressure Pt5 is higher than P0, a flow originates in the upstream
Pedagogical guide
space and moves towards the downstream space.

- The larger the difference between pressures, the greater the flow

 As the nozzle is convergent, gases are accelerated by expansion.

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29
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CONVERGENT, DIVERGENT AND VARIABLE AREA
COURSEWARE NOZZLES
MODULE 15
Study of convergent jet nozzles
GAS TURBINE
ENGINE
Fixed exhaust convergent area nozzle.
B1 category
 If upstream pressure Pt5 continues to increase, gases reach a
Lesson 07 maximum speed in the nozzle throat.
EXHAUST
- This speed is equal to sonic speed (M=1).

- As speed is maximum, so is the gas mass flow rate and thrust.

 The relationship between total pressure and static pressure in the

Table of contents throat, known as critical ratio Rc, takes the value : Rc  1,9.

Study and Operation  In practice, the real ratio Rr is different from Rc.
Pedagogical guide

27 May 2020

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 PART- 66
CONVERGENT, DIVERGENT AND VARIABLE AREA
COURSEWARE NOZZLES
MODULE 15
Study of convergent jet nozzles
GAS TURBINE
ENGINE
Fixed exhaust convergent area nozzle.
B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide

27 May 2020

31
 PART- 66
CONVERGENT, DIVERGENT AND VARIABLE AREA
COURSEWARE NOZZLES
MODULE 15
Study of convergent jet nozzles
GAS TURBINE
ENGINE
Fixed exhaust convergent area nozzle.
B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide

27 May 2020

32
 PART- 66
CONVERGENT, DIVERGENT AND VARIABLE AREA
COURSEWARE NOZZLES
MODULE 15
Study of convergent jet nozzles
GAS TURBINE
ENGINE
Fixed exhaust convergent area nozzle.
B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide

27 May 2020

33
 PART- 66
CONVERGENT, DIVERGENT AND VARIABLE AREA
COURSEWARE NOZZLES
MODULE 15
Study of convergent jet nozzles
GAS TURBINE
ENGINE
Fixed exhaust convergent area nozzle.
B1 category
 Conclusion:
Lesson 07
EXHAUST - Every constant section nozzle is adapted to a given altitude and to
a precise turbojet engine rating.

- Complete expansion is thus carried out only under well defined

conditions.

Table of contents - The ideal compromise is thus sought when designing an exhaust
duct for an engine intended to propel an aircraft at subsonic
Study and Operation speeds.
Pedagogical guide

27 May 2020

34
 PART- 66
CONVERGENT, DIVERGENT AND VARIABLE AREA
COURSEWARE NOZZLES
MODULE 15
Study of convergent jet nozzles
GAS TURBINE
ENGINE
Variable exhaust convergent area nozzle.
B1 category
 For the nozzle to adapt continuously to every engine rating,
Lesson 07 manufacturers have developed various processes:
EXHAUST
- the bucket (or half-shell) system.

- the multi-flap system.

 They allow the adaptation to various engine ratings.

Table of contents
 They enable, indirectly, the control of turbine temperature
Study and Operation

Pedagogical guide

27 May 2020

35
 PART- 66
CONVERGENT, DIVERGENT AND VARIABLE AREA
COURSEWARE NOZZLES
MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents
Variable exhaust convergent area nozzle: The bucket system
Study and Operation

Pedagogical guide

27 May 2020

36
 PART- 66
CONVERGENT, DIVERGENT AND VARIABLE AREA
COURSEWARE NOZZLES
MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents
Variable exhaust convergent area nozzle: The multi-flap system
Study and Operation

Pedagogical guide

27 May 2020

37
 PART- 66
CONVERGENT, DIVERGENT AND VARIABLE AREA
COURSEWARE NOZZLES
MODULE 15
Study of convergent - divergent exhaust nozzle
GAS TURBINE
ENGINE
The Mach number behind the turbine is lower than 1 (M < 1).
B1 category
The duct behind the turbine always has a convergent shape.
Lesson 07
EXHAUST Principle of operation

 By connecting a divergent channel to the convergent nozzl after the

throat, the flow can be accelerated (Hugoniot’s Theorem)

 If the generating pressure Pt5 is sufficient, gases circulate past the

Table of contents nozzle’s throat at Mach 1, and continue expanding in the divergent
duct, with an increasing exhaust velocity: M > 1
Study and Operation

Pedagogical guide

27 May 2020

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 PART- 66
CONVERGENT, DIVERGENT AND VARIABLE AREA
COURSEWARE NOZZLES
MODULE 15
Study of convergent - divergent exhaust nozzle
GAS TURBINE
ENGINE
The convergent-divergent duct enables supersonic exhaust velocities (past the
B1 category throat).

Lesson 07 Because engine ratings are variable, the divergent duct must also be variable.
EXHAUST
 The primary duct is convergent and has a variable section

 The secondary duct may have a variable section, depending on flight

conditions (convergent or divergent).

Table of contents

Study and Operation

Pedagogical guide

27 May 2020

39
 PART- 66 ENGINE NOISE REDUCTION
COURSEWARE

MODULE 15
Origin of the noise
GAS TURBINE
ENGINE
The streamwise vortices generated in a jet flow, in addition to the azimuthal (or
B1 category ring type) vortices, have been found to mix fluid streams even more efficiently)

Lesson 07  Both the azimuthal and streamwise vorticities are of equal importance
EXHAUST to jet mixing process and they are not independent of each other.

 The distortion of azimuthal vortex structure may lead to streamwise

vortices under certain conditions.

 The streamwise vortices in jet mixing flows can be generated by many

Table of contents methods.

Study and Operation

Pedagogical guide

27 May 2020

40
 PART- 66 ENGINE NOISE REDUCTION
COURSEWARE

MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide
Exhaust noise

27 May 2020

41
 PART- 66 ENGINE NOISE REDUCTION
COURSEWARE

MODULE 15
Solutions
GAS TURBINE
ENGINE
Flow mixture.
B1 category
 Design enabling flow mixture before their backward ejection.
Lesson 07
EXHAUST  Significant reduction in exhaust gas noise, and in some cases, an
improvement in nacelle aerodynamics.

Table of contents

Study and Operation

Pedagogical guide

27 May 2020

42
 PART- 66 ENGINE NOISE REDUCTION
COURSEWARE

MODULE 15
Solutions
GAS TURBINE
ENGINE
Lobed nozzles.
B1 category
 A lobed nozzle used to generate large-scale streamwise vortices in a
Lesson 07 jet flow has been considered to be a promising method for jet mixing
EXHAUST enhancement.

Table of contents

Study and Operation

Pedagogical guide

27 May 2020

43
 PART- 66 ENGINE NOISE REDUCTION
COURSEWARE

MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide

Turbofan Lobed Mixer Nozzle

27 May 2020

44
 PART- 66 ENGINE NOISE REDUCTION
COURSEWARE

MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide Turbofan Lobed Mixer Nozzle

27 May 2020

45
 PART- 66 THRUST REVERSERS
COURSEWARE

MODULE 15
Function
GAS TURBINE
ENGINE
Reverse the whole or part of the propelling flow in order to create an
B1 category aerodynamic braking force.

Lesson 07 This makes it possible to assist the braking of the aircraft.

EXHAUST
 They improve deceleration on slippery runway.

 They reduce brake wear.

Table of contents

Study and Operation

Pedagogical guide

27 May 2020

46
 PART- 66 THRUST REVERSERS
COURSEWARE

MODULE 15
Location
GAS TURBINE
ENGINE
Generally, thrust reversers are located in the rear part of a single flow turbojet
B1 category and in an intermediate position in a modern dual flow turbojet.

Lesson 07
EXHAUST

Single flow turbojet

Table of contents

Study and Operation

Pedagogical guide

27 May 2020

Dual flow turbojet

47
 PART- 66 THRUST REVERSERS
COURSEWARE

MODULE 15
Study of the gas stream
GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide
When analysing the formula, we realize that in order to obtain an effective
opposite thrust, are required:

 a high aircraft speed (i.e. as soon as possible after landing),

27 May 2020
 a re-orientation of the ejected flow as forward as possible
(manufacturers limit the angle  to 45° forward to avoid engine stall
and runway remains ingestion).
48
 PART- 66 THRUST REVERSERS
COURSEWARE

MODULE 15
Principle
GAS TURBINE
ENGINE
Thrust reversers obey the same principle: to try and redirect the propelling flow
B1 category ahead for it to hit atmospheric air head-on.

Lesson 07 So as to avoid interferences between the air sucked by the engine and the
EXHAUST reversed flow, the ejection angle of reversed flow is generally limited to 45°.

 The unfolding of thrust reversers occurs when engine idles.

 Engine rating increases only when the spreading out sequence is

completed.
Table of contents
 The resulting reversed thrust is about 40% of takeoff thrust (full
Study and Operation power).
Pedagogical guide

27 May 2020

49
 PART- 66 THRUST REVERSERS
COURSEWARE

MODULE 15
Various types
GAS TURBINE
ENGINE
Eyelid (shell) type thrust reversers.
B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide

27 May 2020

50
 PART- 66 THRUST REVERSERS
COURSEWARE

MODULE 15
Various types
GAS TURBINE
ENGINE
Cascade type thrust reversers.
B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide

27 May 2020

51
 PART- 66 THRUST REVERSERS
COURSEWARE

MODULE 15
Various types
GAS TURBINE
ENGINE
Petal (prop-fan) type thrust reversers.
B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide

27 May 2020

52
 PART- 66 THRUST REVERSERS
COURSEWARE

MODULE 15
Turbo-propellers
GAS TURBINE
ENGINE
The thrust reversing on a turbo-propeller is carried out by inverting the pitch of
B1 category the propeller.

Lesson 07  This is done thanks to the propeller governor:

EXHAUST
- when thrust reversing is engaged, it swivels each blade ;

- when engine power increase, a thrust force opposite to the

direction of aircraft motion is created.

Table of contents

Study and Operation

Pedagogical guide

27 May 2020

53
 PART- 66 THRUST REVERSERS
COURSEWARE

MODULE 15
Reversers spreading out
GAS TURBINE
ENGINE
As soon as levers are switched:
B1 category
 The reverse system opens, driven by jacks,
Lesson 07
EXHAUST  Indicators describing the system unlocked state light up (amber
warning lights): [REV UNLK].

 Indicators describing the system opened state light up (green lights) :

[REV ]

Table of contents  Amber lights [ REV UNLK ] go out

Study and Operation  Reverse thrust levers are then free of movement.
Pedagogical guide  Reverse thrust can be increased by pulling the reverse levers
backwards

27 May 2020

54
 PART- 66 THRUST REVERSERS
COURSEWARE

MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide

Thrust reverse lever and indicators

27 May 2020

55
 PART- 66 THRUST REVERSERS
COURSEWARE

MODULE 15
Interfaces
GAS TURBINE
ENGINE
The thrust reverse assembly on an aircraft equipped with turbojet is often
B1 category connected to the brake system.

Lesson 07  Thus the aerodynamic brake system, called " Ground Spoilers "
EXHAUST function (which acts on the automatic deployment of slowing down
surfaces on the ground) can be activated as soon as the reverse lever
has its deployment position unlocked,

 For that purpose it is necessary of course that all the usual operation
conditions of such a system should be met (aircraft on ground, throttle
Table of contents control levers in idling position,...).

Study and Operation The thrust reverser assembly on an aircraft equipped with turbojet is often
connected to the anti-stall control system.
Pedagogical guide
 The VBV position can be affected by the use of the thrust reverse
assembly.

 Thus the theoretical opening surface of the valves can be increased

up to reaching a fixed value when reversers are used
27 May 2020

56
 PART- 66 THRUST REVERSERS
COURSEWARE

MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide
V.B.V.

27 May 2020

57
 PART- 66 THRUST REVERSERS
COURSEWARE

MODULE 15
Maintenance
GAS TURBINE
ENGINE
The forces actuating thrust reversers are very significant in order to ensure the
B1 category correct operation in spite of the aerodynamic and mechanical stresses.

Lesson 07 The greatest precaution is required when inspecting or repairing this system.
EXHAUST
 It is important for the system to be deactivated when work is to be
done on it, so as to prevent any risk of accident.

 It may also be deactivated and set in locked position in order to allow

the departure of an aircraft: thrust reversers would be inoperative :
Table of contents

Study and Operation

Pedagogical guide

27 May 2020

58
 PART- 66 THRUST REVERSERS
COURSEWARE

MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide

Maintenance

27 May 2020

59
 PART- 66 THRUST REVERSERS
COURSEWARE

MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide

Maintenance

27 May 2020

60
 PART- 66 THRUST REVERSERS
COURSEWARE

MODULE 15

GAS TURBINE
ENGINE

B1 category

Lesson 07
EXHAUST

Table of contents

Study and Operation

Pedagogical guide

Maintenance

27 May 2020

61