Ameco Beijing

Aviation College

Training Manual
Fundamentals
Jet
Aircraft
Maintenance
Fundamentals

ATA 76
Engine Controls

JAR-66

Lufthansa Issue: July 2000

Technical Training GmbH For Training Purposes Only
Book No: JAMF ATA 76 ALL Lufthansa Base ã Lufthansa 1995
For training purpose and internal use only.
Copyright by Lufthansa Technical Training GmbH.
All rights reserved. No parts of this training
manual may be sold or reproduced in any form
without permission of:

Lufthansa Technical Training GmbH

Lufthansa Base Frankfurt

D-60546 Frankfurt/Main
Tel. +49 69 / 696 41 78
Fax +49 69 / 696 63 84

Lufthansa Base Hamburg

Weg beim Jäger 193
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Tel. +49 40 / 5070 24 13
Fax +49 40 / 5070 47 46
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Aviation College
ATA 76 ENGINE CONTROLS
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Page 1
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ENGINE CONTROLS
ENGINE START CONTROLS
Ameco Beijing FUNDAMENTALS

Aviation College ATA 76 Lesson 1

ENGINE START CONTROLS

INTRODUCTION TO ENGINE CONTROLS
The main engine controls are the engine start controls, the forward
thrust controls and the reverse thrust controls.
The start lever is used to switch fuel on and off and to switch ignition on during
engine start.
The forward thrust lever is used to control the thrust of an engine between idle
and take--off thrust. The lever informs the fuel control unit how much thrust is
requested by the pilot.
The third engine control is the reverse thrust lever.
When the reverse thrust lever is activated the deflector doors are deployed and
the airflow is deflected to give reverse thrust.
When the reverse thrust lever is pushed down the deflector doors move to the
stowed position and the engine delivers forward thrust.
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Aviation College ATA 76 Lesson 1

FORWARD THRUST
LEVER

REVERSE THRUST START

LEVER LEVER
For Training Purposes Only

THRUST CONTROL SIGNAL

Figure 1 Mechanical Engine Controls

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Aviation College ATA 76 Lesson 1

Introduction to Engine Controls
You can find similar engine controls on modern aircraft like this Airbus 320.
The master switches on the engine start panel are used to control the engine
start sequence, the control levers help to set the required thrust and the
reverse latching levers are used with the control levers to give reverse thrust.
For Training Purposes Only

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Aviation College ATA 76 Lesson 1

REVERSE CONTROL
LATCHING LE- LEVER
VER

ENGINE
FWD START
THRUST PANEL
START CONTROL SIGNAL

FUEL IGNITION
ON ON

RESOLVER
For Training Purposes Only

ECU

THRUST CONTROL SIGNAL

REVERSE CONTROL SIGNAL

Figure 2 Electrical Engine Control

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Aviation College ATA 76 Lesson 1

START CONTROLS OVERVIEW

The last segment that the ignition and the fuel supply to the combustion
chamber are switched on by the engine start lever.
The fuel is supplied via a high pressure fuel shut--off valve and a low pressure
fuel shut--off valve.
The low pressure fuel shut--off valve is usually an electric motor driven valve.
The position of this valve is indicated by the fuel valve closed light. This light
illuminates when the valve is closed and goes out when the valve is open.
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Aviation College ATA 76 Lesson 1

LP FUEL
VALVE
For Training Purposes Only

Figure 3 LP Fuel Valve Control

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Aviation College ATA 76 Lesson 1

HP FUEL VALVE CONTROL

On this aircraft the high pressure fuel shut off valve is mechanically controlled.
The HP valve opens when the engine start lever is moved up and closes when
the lever is moved down.
The position of the HP fuel shut--off valve is indicated by the position of the
engine start lever.
For Training Purposes Only

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Aviation College ATA 76 Lesson 1

HP
FUEL
VALVE
For Training Purposes Only

Figure 4 HP Fuel Valve Control

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Aviation College ATA 76 Lesson 1

ELECTRICAL START CONTROLS

On some aircraft, for example the Airbus A320, the LP fuel valve position is
indicated on the ECAM display.
It is controlled by the engine master switch.
The HP fuel valve is not indicated directly but you know when it is open by the
fuel flow indication, the increase in the exhaust gas temperature or, by the fuel
used indication.
For Training Purposes Only

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Aviation College ATA 76 Lesson 1

START CONTROL SIGNAL

LP
CLOSE
FUEL
VALVE
HP
For Training Purposes Only

OPEN
FUEL
VALVE

ECU

Figure 5 Electrical Start Controls Indication

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Aviation College ATA 76 Lesson 1

LP FUEL VALVE CONTROL

The low pressure fuel shut--off valve on modern Airbus aircraft is controlled by
the engine master switch.
You may remember from the Fire Protection lessons that this valve is also
called the fire shut--off valve and therefore it is also controlled by the engine fire
switch.
When you operate the fire switch the fire relay opens and the low pressure fuel
shut--off valve closes.
The amber colour of the valve symbol on the ECAM display indicates an
emergency closure of the valve.
The engine fire switch always has priority over the engine master switch.
This applies on all aircraft with electrically controlled low pressure fuel shut--off
valves.
Mechanically controlled low pressure fuel shut--off valves are only found on
very old aircraft. They are not described in this lesson.
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Aviation College ATA 76 Lesson 1

START CONTROL SIGNAL

CLOSE LP FUEL
VALVE
For Training Purposes Only

OPEN

ECU

Figure 6 LP Fuel Valve Control

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Aviation College ATA 76 Lesson 1

MECHANICAL HP FUEL VALVE CONTROL

The controls for mechanical high pressure fuel shut off valves are routed from
the cockpit below the cabin floor to the center section and then via the wing
leading edges and the pylons to the fuel control units.
The engine start lever has detents to secure it in the idle and cut--off positions.
Inputs from the lever are transmitted via rods, pulleys and cables to the start
drum in the pylon.
The start drum is connected to the fuel control unit via a long push pull cable.
Mechanically controlled high pressure fuel shut--off valves are usually found on
older aircraft types. Mechanical controls are more reliable than electrical
controls but they are heavier and they usually require more adjustments.
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Aviation College ATA 76 Lesson 1

ADVANTAGE DISADVANTAGE
START
DRUM

START
DRUM

FCU

START
CABLE START
DRUM

TO EN-
GINE

HP PUSH-PULL
FUEL CABLE
VALVE
For Training Purposes Only

Figure 7 Mechanical Hp Fuel Valve Control

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Aviation College ATA 76 Lesson 1

ELECTRICAL HP FUEL VALVE CONTROL

Electrical high pressure fuel shut--off valves are normally found on modern
aircraft engines. They are located behind the fuel metering valve in the fuel
control unit. They can be motor controlled or solenoid controlled, but they have
similar construction.
Here you can see a more detailed view of the high pressure fuel shut--off valve
in the fuel control unit.
The valve assembly has two main parts -- the electrical component which
controls the servo valve and a spring loaded shut--off valve which is connected
to the servo valve. The spring loaded valve is usually called the pressurizing
valve.
The high pressure fuel flows across the partially open fuel metering valve and
then through the servo valve to the aft side of the pressurizing valve. The high
pressure fuel and the spring force keeps the pressurizing valve in the closed
position if the start lever is at cut--off.
This example shows a HP valve with a standard single coil solenoid. Note that
the solenoid is energized when the HP shut--off valve is closed.
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Aviation College ATA 76 Lesson 1

For Training Purposes Only

Figure 8 Electrical HP Fuel Valve OFF Postition

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Electrical hp fuel valve control cont.
When the start lever is moved to idle the solenoid is de--energized and the
servo valve moves down.
The pressure on the aft side of the pressurizing valve escapes into the case of
the fuel control unit.
The pressure from the high pressure fuel pump pushes the pressurizing valve
open and the fuel can flow to the fuel nozzles.
When the start lever is moved to the cut--off position the solenoid is energized
and the servo valve moves up.
This allows the fuel pressure to enter the aft side of the pressurizing valve
piston. The piston closes and the supply to the fuel nozzles is cut--off.
The critical disadvantage of this single coil solenoid control system is that if the
electrical signal is lost the high pressure fuel shut--off valve cannot be closed.
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For Training Purposes Only

Figure 9 Electrical HP Fuel Valve Open Position

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Aviation College ATA 76 Lesson 1

Electrical hp fuel valve control cont.
Other aircraft have dual coil solenoids at the HP valve as you can see here.
These solenoids need electrical power to close the valve and to open the valve.
The danger is that the valve can move to the closed position if there’s a short
circuit because of a damaged wire -- even if the start lever is in idle.
Aircraft manufacturers have added protection circuits to prevent this dangerous
situation.
These protection circuits differ from aircraft to aircraft. Here you see a
simplified example where the pressurizing valve is equipped with a limit switch.
The limit switch is activated by the plunger of the pressurizing valve.
When the start lever is moved to idle the open coil of the dual solenoid is
energized and the servo valve moves down.
This moves the pressurizing valve up and the plunger activates the limit switch.
The limit switch de--energizes the protection relay and this disconnects the
electrical power from the solenoid.
This makes sure that the valve cannot move by mistake.
Remember that this is a simplified example. On many aircraft the power supply
and the ground are disconnected from the electrical control element.
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Aviation College ATA 76 Lesson 1

For Training Purposes Only

Figure 10 Protection Circuit HP Fuel Valve

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Aviation College ATA 76 Lesson 2

MECHANICAL THRUST CONTROLS

INTRODUCTION
The mechanical thrust control system transmits the thrust lever input signals to
the fuel control unit on the engine. The forward thrust levers are also called the
throttles. They are located on the center pedestal. There is one thrust lever for
each engine.
The main positions of the forward thrust levers are idle and take--off thrust.
The reverse thrust levers are located at the top of the forward thrust levers.
The main positions of the reverse thrust levers are reverse idle and full reverse
thrust.
Forward thrust and reverse thrust use the same components.
At the drum below the trust levers the forward thrust lever rotates the drum
counter clockwise and the reverse thrust lever rotates the drum clockwise.
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Aviation College ATA 76 Lesson 2

THRUST FUEL
LEVER CONTROL
FORWARD UNIT
THRUST
REVERSE LEVER
THRUST
LEVER
For Training Purposes Only

CENTER PEDESTRAL

Figure 11 Mechanical Thrust Control

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Aviation College ATA 76 Lesson 2

FORWARD THRUST CONTROLS

The thrust control system is used to accelerate and decelerate the engine. It
can not be used to shut down the engine.
The thrust control system transmits the thrust lever signal to the fuel control
unit via control rods cables drums and pulleys and flexible controls such as
push pull cables.
Here you can see a simplified schematic of a crank lever transmission.
A power lever transmits the thrust lever signal to the fuel control unit. When the
thrust control levers are in idle the power lever is in the mid position.
If you move the thrust control levers forward the power lever moves up.
If you move the thrust control levers to idle the power lever moves to the mid
position.
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Aviation College ATA 76 Lesson 2

FORWARD
THRUST THRUST FUEL
LEVER LEVER CONTROL
UNIT
PULLEY DRUM

ROD

DRUM

CABLE
PUSH-PULL
CABLE
For Training Purposes Only

POWER
FCU
LEVER

Figure 12 Forward Thrust Control (Push Pull Control)

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Aviation College ATA 76 Lesson 2

Forward thrust controls cont.
Some aircraft use racks and pinions in the transmission instead of crank levers.
Racks and pinions are found at the thrust control drum at the engine pylon and
at the fuel control unit.
The linear movement of the rack is transformed into a circular movement by
the pinion.
For Training Purposes Only

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Aviation College ATA 76 Lesson 2

THRUST
LEVER FUEL
CONTROL
UNIT

PINION

RACK
For Training Purposes Only

FCU

Figure 13 Forward Thrust Control with Rack and Pinion

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Forward thrust controls cont.
A friction brake makes internal friction to keep the throttle control system in a
selected position. The friction must be strong enough to prevent the throttles
moving because of vibration but it must be small enough to move the throttles
easily. The friction brake can be a separate component as you can see on the
video or it can be an integral part of the autothrottle servo mechanism. The
friction brake can usually be adjusted.
The autothrottle servo mechanism receives signals from the autothrottle
computer and uses an electrical servo motor to move the thrust lever and the
mechanical transmission components and therefore change the power setting
for the engine.
A coupling unit or an integral friction brake makes sure that the autothrottle
servo motor can be disconnected from the mechanical control system.
A set of microswitches below the center pedestal are activated by the thrust
control levers.
These switches are used for warnings and controls which depend on the lever
position -- for example take--off warning, cabin pressurization and thrust
reverser activation.
For Training Purposes Only

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Aviation College ATA 76 Lesson 2

MICROSWITCH
UNIT

AUTOTHROTTLE
SERVO MECHANISM
(WITH FRICTION
BRAKE)

FRICTION
BRAKE
AUTOTHROTTLE SERVO MECHANISM
For Training Purposes Only

CONTROL
CABLES

FRICTION BRAKE

SEVO MOTOR
FROM AUTOTHROTTLE
COMPUTER
Figure 14 Friction Brake
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Aviation College ATA 76 Lesson 2

FORWARD THRUST CONTROLS - ADJUSTMENT

All mechanical control systems must be adjusted to operate properly. The
adjustment of the engine thrust control systems is usually split in two parts.
The controls between the cockpit and the pylon are adjusted in one procedure
and the controls between the pylon and the fuel control unit are adjusted
seperately.
The splitting point is usually the thrust control drum at the engine pylon.
The adjustment between the cockpit and the pylon is usually done with the
thrust levers in idle and the adjustment between the pylon and the fuel control
unit is usually done with the thrust levers in a defined part power position.
You can find the rig points where the transmission changes from one method to
another -- for example from control rods to cables as.
Note that a travel check is necessary after adjustment of the thrust control
system. This is to make sure that the thrust control levers can be moved over
the full range between idle and full forward thrust and between idle and full
reverse thrust. The travel check is also to make sure that all rig pins are
removed.
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Aviation College ATA 76 Lesson 2

RIGGING RIGGING
PIN PIN

RIGGING
PIN

RIGGING
PIN
For Training Purposes Only

FCU
RIGGING
PIN

Figure 15 Thrust Control-Adjustment

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Aviation College ATA 76 Lesson 2

REVERSE THRUST CONTROLS INTRODUCITON

The reverse thrust controls have three tasks -- to activate the thrust reverser to
increase engine power and to block the reverse thrust lever while the reverser
moves from the stowed to the deployed position.
The reverse thrust control system uses the same mechanical control
components as the forward thrust control system. In addition it has
microswitches below the center pedestal to activate the thrust reversers. The
system also has a mechanical linkage, known as the throttle interlock system,
to prevent the pilot from increasing engine power until the reverser is fully
deployed.
The reverse thrust control lever has three main positions -- one for each task.
The normal position is used to stow the reverser the reverse idle position is
used to activate the reverser. Here the lever is blocked by the throttle interlock.
The full reverse throttle position is used to increase engine power.
The throttle interlock system is the main difference between the reverse thrust
control system and the forward thrust control system.
It is usually installed on the engine pylon and controlled by a mechanical
feedback system. This feedback system is connected to the thrust control
system and the thrust reverser.
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Aviation College ATA 76 Lesson 2

REVERSER
DEPLOYED

MICROSWITCH
UNIT REVERSER
FULL REVERSER FEEDBACK
THROTTLE CABLE RH
THROTTLE
REVERSER INTERLOCK
IDLE SYSTEM

NORMAL

REVERSER
For Training Purposes Only

FEEDBACK
CABLE LH

Figure 16 Reverse Thrust Control

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Aviation College ATA 76 Lesson 2

THROTTLE INTERLOCK - OPERATION

The throttle interlock system locks the mechanical control system while the
thrust reverser is moving from the stowed to the deployed position. This
prevents damage to the reverser system and makes sure that the reverser is
fully deployed and latched before reverse power can be applied.
On this example of a Boeing 737 thrust control system the mechanical interlock
linkage is located in the strut drum control box where the thrust control cables
and the reverser feedback cables are connected.
When you look inside the strut drum control box you can see the thrust control
drum the thrust control rack with the thrust push pull cable and the pinion with
rollers on it.
You can also see the reverser feedback push pull cable and the reverser
feedback cam.
For Training Purposes Only

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Aviation College ATA 76 Lesson 2

THRUST
CONTROL
THRUST DRUM
CONTROL
CABLE
STRUT DRUM
CONTROL BOX

THRUST REVERSER
For Training Purposes Only

FEEDBACK PUSH-PULL
CABLES
TO ENGINE FUEL
CONTROL UNIT

Figure 17 Throttle Interlock

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Aviation College ATA 76 Lesson 2

throttle interlock - operation cont.
When the reverse thrust control lever is moved to reverse idle the thrust control
pinion rotates counter clockwise until the lower roller contacts the cam of the
reverser feedback cam. No further movement is possible but the reverser is
activated by the micro switch below the control levers in the cockpit.
When the reverser deploys the reverse feedback mechanism rotates the
reverser feedback cam clockwise.
When the reverser is fully deployed the contact surface of the feedback cam
doesn’t block the roller of the thrust control pinion any more.
This allows you to pull the reverse thrust control lever to get full reverse power.
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Aviation College ATA 76 Lesson 2

FULL REVERSE
REVERSER
THROTTLE
DEPLOYED
REVERSE
IDLE

NORMAL
For Training Purposes Only

Figure 18 Throttle Interlock

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Aviation College ATA 76 Lesson 2

LEVER LOCK SYSTEM

You learned that the forward thrust control signal moves the power lever on the
fuel control unit in one direction and the reverse thrust control signal moves it in
the opposite direction.
Engine control systems have a thrust lever lock system to make sure that the
forward thrust lever and the reverse thrust lever can not be activated at the
same time. This system differs from aircraft to aircraft but it is usually a
mechanical device. It locks the reverse thrust lever if the forward thrust lever is
out of idle and it locks the forward thrust lever if the reverse thrust lever is
pulled.
The thrust lever assembly has a movable part a fixed part and a rocker arm
with two rollers. The rocker arm connects the fixed sector, the throttle lever and
the moving sector.
In the idle position the rocker arm can toggle into detents on the fixed sector
and on the moving sector.
When the throttle control lever is pushed forward the forward roller of the
rocker arm moves into a detent on the moving sector and the aft roller moves
on to the cam of the fixed sector. In this condition you can not lift the thrust
reverser control lever because the two rollers of the rocker arm are locked.
When the thrust reverser control lever is lifted the aft roller of the rocker arm
moves into a detent on the fixed sector and the forward roller moves on to the
cam of the moving sector. In this condition you can not push the throttle control
lever to take off.
For Training Purposes Only

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For Training Purposes Only

Figure 19 Lever Lock System

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Aviation College ATA 76 Lesson 3

ELECTRICAL THRUST CONTROLS

FORWARD THRUST CONTROLS-INTRODUCTION
Electriacl thrust control systems use electrical signals to transmit the thrust
demand signal from the thrust control levers in the cckpit to the engines.
For safety reasons two separate thrust control signals are sent from each
control lever to the associated electronic control unit at the engine.
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Aviation College ATA 76 Lesson 3

HP FUEL LP FUEL VALVE

VALVE

ENGINE2
REVERSE LATCHING CONTROL
LEVER LEVER

ECU

CHANNEL A
CHANNEL B LP FUEL VALVE
CHANNEL A HP FUEL
VALVE
For Training Purposes Only

CHANNEL B

ECU

ENGINE1

Figure 20 Electrical Forward Thrust Control

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Aviation College ATA 76 Lesson 3

forward thrust controls-Introduction cont.
The thrust control levers are similar to those in a mechanical thrust control
system. They are usually connected to a mechanical linkage below the control
stand.
The movement of the thrust control levers is transmitted via control rods and
bellcranks to the resolvers.
There are two resolvers for each thrust control lever. The resolvers are
electrical components which convert the angular deflection of the input lever to
a voltage signal.
An artificial feel mechanism is used to simulate a higher resistance in the
mechanical transmission system. The resistance is low because there are very
few mechanical parts. The artificial feel mechanism is important because it
gives the pilot a feel for the resistance in the system.
On some aircraft the artificial feel mechanism is also used as a friction brake.
Some modern aircraft, like the Boeing 747--400,on the left graphic have the
autothrottle servo mechanism connected to the mechanical linkage below the
center pedestal. This servo mechanism is used to move the throttle levers by
the autothrottle computers. It also gives artificial feel and is used as a friction
brake.
Other modern aircraft, like the latest generation of Airbus aircraft, do not have
an autothrottle servo unit. This means that the thrust control levers do not
move when the autothrottle computer selects a new power setting.
For Training Purposes Only

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Aviation College ATA 76 Lesson 3

THRUST
CONTROL
LEVERS

CONTROL
ROD

BELLCRANK
ARTIFICAL
FEEL
RESOLVER MECHANISM
For Training Purposes Only

AUTOTHROTTLE
SERVO MECHANISM RESOLVER

Figure 21 Artificial Feel Unit (including Friction Brake)

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Aviation College ATA 76 Lesson 3

FORWARD THURST CONTROLS - OPERATION

In this segment we look at the operation of an electrical forward thrust control
system. These systems use mechanical input signals to move the input levers
of the resolvers.
The forward thrust control lever can be set in all positions between idle and full
forward thrust.
On some aircraft the forward thrust control levers have detents for the most
commonly used thrust settings such as maximum climb, maximum continuous
and reverse idle.
On these levers a spring loaded roller fits into the detents on the cam in the
artificial feel unit.
The full forward thrust lever position is determined by a mechanical stop in the
control stand.
Electrical thrust control systems also have rig points because of the
mechanical transmission below the control stand.
The more mechanical parts the system has the more rig points you will find in
it.
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Aviation College ATA 76 Lesson 3

FORWARD THRUST
CONTROL LEVER

STOP

CAM

DETENT
ARTIFICIAL
For Training Purposes Only

FEEL UNIT

ROLLER
SPRING

Figure 22 Operation of Forward Thrust Control

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ENGINE CONTROLS
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Aviation College ATA 76 Lesson 3

REVERSE THRUST CONTROLS

Electrical reverse thrust controls are similar to mechanical controls. This means
these systems also have a reverse thrust lever mechanical and an electrical
signal transmission, a reverser interlock system, lever lock system and control
switches.
The purpose of these components and sub systems in the electrical reverse
control system is the same as in the mechanical system.
The reverse thrust lever has three main positions -- one for each task.
The normal position is used to stow the reverser, the reverse idle position is
used to activate the reverser and the full reverse throttle position is used to
increase engine power.
Mechanical components in the control pedestal transmit the reverse thrust
lever movement to the resolvers. The resolvers convert the mechanical signal
to a voltage signal that is transmitted to the engine control unit.
The throttle interlock system locks the reverser control system while the thrust
reverser is moving from the stowed to the deployed position.
The thrust lever lock system makes sure that the forward thrust lever and the
reverse thrust lever can not be activated at the same time.
The control switches are used for warnings and controls which depend on the
lever position -- for example take--off warning, cabin pressurization and thrust
reverser activation.
For Training Purposes Only

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ENGINE CONTROLS
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Aviation College ATA 76 Lesson 3

REVERSE
THRUST
LEVER

REVERSE
THRUST
LEVER

REVERSER LEVER
LOCK PIN

CONTROL
SWITCHES

MECHANICAL
TRANSMISSION
For Training Purposes Only

THROTTLE
INTERLOCK
MECHANISM
RESOLVER

Figure 23 Thrust Lever/Reverse Lever Lock System

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Ameco Beijing FUDNAMENTALS

Aviation College ATA 76 Lesson 3

reverse thrust controls cont.
The reverser interlock system prevents that you can pull the reverse lever
further to full reverse thrust until the reverser is fully deployed.
This interlock protection is actually not always necessary on FADEC controlled
engine, because the FADEC can monitor the deployment of the reverser and
increase the fuel flow to the engine if the reverser is fully deployed.
As a result you will find that some aircraft do not have a throttle interlock
system.
For Training Purposes Only

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Aviation College ATA 76 Lesson 3

ENGINE
START
REVERSE PANEL
THRUST

FORWARD
THRUST
For Training Purposes Only

ECU

THRUST CONTROL SIGNAL

Figure 24 Electrical Reverse Thrust Control

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Aviation College ATA 76 Lesson 3

reverse thrust controls cont.
On aircraft with FADEC controlled engines you usually find throttle interlock
systems only if they have 4 engines.
These aircraft need a throttle interlock system to prevent dangerous situations
if a reverser fails to deploy.
When a reverser of an outer engine fails to deploy while the others operate in
full reverse thrust the aircraft gets a very strong yaw momentum because three
engines give reverse thrust and one engine gives forward idle thrust.
This can throw the aircraft from the runway and lead to a severe crash because
the yaw movement can not be counteracted by the nose wheel steering
system.
When a reverser of an inner engine fails to deploy the aircraft gets a yaw
momentum because three engines give reverse thrust and one engine gives
forward idle thrust.
This yaw momentum can usually be counteracted by the nose wheel steering
system because of the relatively short distance between an inner engine and
the yaw axis.
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Aviation College ATA 76 Lesson 3

For Training Purposes Only

Figure 25 Effect fo Reverser Failure

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Aviation College ATA 76 Lesson 3

reverse thrust controls cont.
On FADEC controlled aircraft the throttle interlock system prevents asymmetric
operation of the reversers.
Different methods are used.
On some aircraft all reverser control levers are protected by individual
electromechanical interlock actuators. The interlock mechanism locks the
mechanical linkage when the respective reverser is not fully deployed.
On other aircraft only the outer engines are protected by a throttle interlock
system. On this A340 for example, the FADEC systems of the two outer
engines communicate with each other. They lock the reverse levers of the
outer engines until the two outer reversers are deployed.
For Training Purposes Only

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Aviation College ATA 76 Lesson 3

REVERSE
THRUST
LEVER INTERLOCK
ACTUATOR
For Training Purposes Only

THROTTE
INTERLOCK
ACTUATOR
Figure 26 Throttle Interlock System
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Aviation College ATA 76 Lesson 3

reverse thrust controls cont.
On the A320 you can find another difference to typical electrical reverser
control systems. This aircraft has a reverse latching lever instead of a reverse
thrust lever.
The reverse latching lever releases the throttle control lever so that it can be
pulled further aft out of the idle position for full reverse power.
For Training Purposes Only

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Aviation College ATA 76 Lesson 3

REVERSE
LATCHING
LEVER

REVERSE
LATCHING
LEVER
For Training Purposes Only

Figure 27 Reverse Latching Lever

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Aviation College ATA 76 Lesson 3

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 Ameco Beijing
Aviation College
TABLE OF CONTENTS
ATA 76 ENGINE CONTROLS . . . . . . . . . . . . . . . . . 1
ENGINE START CONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
INTRODUCTION TO ENGINE CONTROLS . . . . . . . . . . . 2
START CONTROLS OVERVIEW . . . . . . . . . . . . . . . . . . . . 6
HP FUEL VALVE CONTROL . . . . . . . . . . . . . . . . . . . . . . . . 8
ELECTRICAL START CONTROLS . . . . . . . . . . . . . . . . . . . 10
LP FUEL VALVE CONTROL . . . . . . . . . . . . . . . . . . . . . . . . 12
MECHANICAL HP FUEL VALVE CONTROL . . . . . . . . . . 14
ELECTRICAL HP FUEL VALVE CONTROL . . . . . . . . . . . 16
MECHANICAL THRUST CONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . . 22
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
FORWARD THRUST CONTROLS . . . . . . . . . . . . . . . . . . . 24
FORWARD THRUST CONTROLS - ADJUSTMENT . . . . 30
REVERSE THRUST CONTROLS INTRODUCITON . . . . 32
THROTTLE INTERLOCK - OPERATION . . . . . . . . . . . . . 34
LEVER LOCK SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
ELECTRICAL THRUST CONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
FORWARD THRUST CONTROLS-INTRODUCTION . . . 40
FORWARD THURST CONTROLS - OPERATION . . . . . . 44
REVERSE THRUST CONTROLS . . . . . . . . . . . . . . . . . . . . 46

Page i
 Ameco Beijing
Aviation College
TABLE OF FIGURES
Figure 1 Mechanical Engine Controls . . . . . . . . . . . . . . . . . . . . . . . . 3
Figure 2 Electrical Engine Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 3 LP Fuel Valve Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure 4 HP Fuel Valve Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 5 Electrical Start Controls Indication . . . . . . . . . . . . . . . . . . . 11
Figure 6 LP Fuel Valve Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Figure 7 Mechanical Hp Fuel Valve Control . . . . . . . . . . . . . . . . . . . 15
Figure 8 Electrical HP Fuel Valve OFF Postition . . . . . . . . . . . . . . . 17
Figure 9 Electrical HP Fuel Valve Open Position . . . . . . . . . . . . . . . 19
Figure 10 Protection Circuit HP Fuel Valve . . . . . . . . . . . . . . . . . . . 21
Figure 11 Mechanical Thrust Control . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 12 Forward Thrust Control (Push Pull Control) . . . . . . . . . . 25
Figure 13 Forward Thrust Control with Rack and Pinion . . . . . . . . 27
Figure 14 Friction Brake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 15 Thrust Control-Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 16 Reverse Thrust Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Figure 17 Throttle Interlock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Figure 18 Throttle Interlock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Figure 19 Lever Lock System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Figure 20 Electrical Forward Thrust Control . . . . . . . . . . . . . . . . . . . 41
Figure 21 Artificial Feel Unit (including Friction Brake) . . . . . . . . . . 43
Figure 22 Operation of Forward Thrust Control . . . . . . . . . . . . . . . . 45
Figure 23 Thrust Lever/Reverse Lever Lock System . . . . . . . . . . . 47
Figure 24 Electrical Reverse Thrust Control . . . . . . . . . . . . . . . . . . . 49
Figure 25 Effect fo Reverser Failure . . . . . . . . . . . . . . . . . . . . . . . . . 51
Figure 26 Throttle Interlock System . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Figure 27 Reverse Latching Lever . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

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