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Garret TFE 731 Turbofan Engine (CAT C)
MAINTENANCE
Page 1 of 34 FOR TRAINING PURPOSES ONLY TFE 731 - ISSUE 2,
2010
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Garret TFE 731 Turbofan Engine (CAT C)
MAINTENANCE
Page 2 of 34 FOR TRAINING PURPOSES ONLY TFE 731 - ISSUE 2,
2010
INTRODUCTION
0 TABLE OF CONTENTS
1 Control System Operation 3 2 Thrust Setting, Normal Mode 4 3
Engine Control System 5 4 Engine Control Indicators 6 5 Engine
Start Panel 7 6 Operating Limits 8 7 Pre-Start Procedure 9 8 Abort
Start 10 9 Initiate Start 11 10 Cut-off to Idle 12 11 Light Off 13
12 Starter Dropout 14 13 Idle 15 14 Acceleration from Idle 16 15
Take-Off N1 Graph 17
16 Take-Off Power (-10 C, Sea Level) 18
17 Take-Off Power (35 C) 19
18 Operating Characteristics 20 18.1 Normal Mode 20 18.2 Manual
Mode 21 19 Power Lever, Manual Mode 22
20 Normal Mode vs. Manual Mode (35 C) 23
21 Normal Mode vs. Manual Mode (0 C, Sea Level) 24
22 Engine Shutdown Procedures 25 23 Adjustment Problems 26 24
EFR Adjustment 27 25 Take-Off Power 28 26 DEEC Climb/Cruise 29 27
T5 Limiter Adjust 30 28 Items Affecting Throttle Matching 31 29
Power Lever Splits 32
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Garret TFE 731 Turbofan Engine (CAT C)
MAINTENANCE
Page 3 of 34 FOR TRAINING PURPOSES ONLY TFE 731 - ISSUE 2,
2010
GROUND/FLIGHT CHECK-OUT
1 CONTROL SYSTEM OPERATION To this point, discussion of the
engine was centred on specific isolated systems. The engine
operating characteristics are a result of the interaction of all
systems. The engine discussion in this section will examine the
operating characteristics and review normal and abnormal engine
operating conditions. The engine operation will consist of a
routine engine start and operation with emphasis on normal
parameters. To accomplish this, a "generic" engine installation
with "typical" cockpit switches and indicators will be used. While
not intended to reflect any specific aircraft installations, the
configuration is applicable to most. The TFE731 engines utilise two
control systems. The primary system consists of an electronic
engine control that schedules fuel through an
electro/hydro-mechanical fuel control. This is the normal mode of
operation. The back-up system consists of a hydro-mechanical fuel
control incorporating a centrifugal speed governor. This is termed
manual mode and is used in the event that the EEC/DEEC becomes
inoperative. Dispatch of the aircraft in manual mode is governed by
specific aircraft flight manual/pilot operating handbook
procedures, and as such will not be discussed in this section.
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Garret TFE 731 Turbofan Engine (CAT C)
MAINTENANCE
Page 4 of 34 FOR TRAINING PURPOSES ONLY TFE 731 - ISSUE 2,
2010
2 THRUST SETTING, NORMAL MODE During the fuel system review,
power lever angle (PLA) was used in reference to degrees movement
of the fuel control input shaft. In normal mode, PLA is sensed in
the electronic control by varying voltage from the PLA
potentiometer. Cut off is referenced at 0 and idle stop is 20. With
the engine operating at idle power, movement of the power lever
from 20 to 26 (40 on some models) does not change engine speed.
This "dead band" area of the PLA is the idle range. The thrust
setting range is from 26(40) to 120. Movement of the power lever to
the maximum position (120) is the normal takeoff power
position.
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Garret TFE 731 Turbofan Engine (CAT C)
MAINTENANCE
Page 5 of 34 FOR TRAINING PURPOSES ONLY TFE 731 - ISSUE 2,
2010
3 ENGINE CONTROL SYSTEM
3.1 Related Components
The power levers are mechanically linked by teleforce and
Teleflex to the engine fuel control. The PLA is sent to the
electronic control in the form of a voltage by the power lever
potentiometer in the fuel control. The EEC/DEEC then sends a signal
to the fuel control, adjusting fuel to correspond to power lever
position. Initial travel of the linkage opens the fuel valve during
both normal and manual modes of operation. Placing the power lever
in the cut off position manually closes the fuel valve. This
provides a positive mechanical means to control fuel to the engine.
The ignition system is energised by micro-switches located in the
power lever pedestal. The annunciator panel contains engine related
advisory lights for oil pressure, fuel pressure and electronic
control. When the electronic control is off, or in the manual mode
and when the oil or fuel pressure is below a determined value, the
lights will illuminate.
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Garret TFE 731 Turbofan Engine (CAT C)
MAINTENANCE
Page 6 of 34 FOR TRAINING PURPOSES ONLY TFE 731 - ISSUE 2,
2010
4 ENGINE CONTROL INDICATORS Five indicators mounted on the main
instrument panel can monitor engine operation. Shown are the N1 and
N2 spool speed indicators, ITT, fuel flow, oil pressure and oil
temperature indicators. Note that the "typical" N1, ITT and fuel
flow indicators shown throughout this section have a digital
indication in addition to the analogue. Range marks are commonly
used to provide instantaneous visual reference.
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Garret TFE 731 Turbofan Engine (CAT C)
MAINTENANCE
Page 7 of 34 FOR TRAINING PURPOSES ONLY TFE 731 - ISSUE 2,
2010
5 ENGINE START PANEL A typical engine start panel, normally
located on the aircraft overhead panel provides the necessary
switches for engine starting. A two-position switch provides for
starting from the battery buss (normal) or from external power. The
switches labelled "CMPTR 1" and "CMPTR 2" controls the electronic
engine control. Those engines equipped with a DEEC utilise a
three-position switch as shown here, while EEC's utilise a
two-position on/off switch. The "IGN" lamps will illuminate when
the ignition system is energised. The three-position switches
labelled "IGNITION-START-MOTOR START STOP" is used to select the
conditions for an engine start. The up position provides continuous
ignition. The centre position is used for normal starts. Moving the
switch down disengages the starter and is used for engine
ses the starter. During subsequent operating procedures, the
operation of switches and controls with reference to the engine
function does not reflect a specific installation. Some aircraft
installations may combine switches with each other and with other
controls. Refer to your specific aircraft document for cockpit
control arrangement and operation.
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Garret TFE 731 Turbofan Engine (CAT C)
MAINTENANCE
Page 8 of 34 FOR TRAINING PURPOSES ONLY TFE 731 - ISSUE 2,
2010
6 OPERATING LIMITS It is important to be aware of engine
operating limits prior to operating the engine. The primary
document is the flight manual. A table of limits is located in the
engine maintenance manual and contains the necessary corrective
actions if limits are exceeded. The table includes engine start
times, oil pressure and temperature limits, ITT limits and rotor
speed limits. The table and the approved aircraft flight manual
should be reviewed prior to operating the engine.
