MODULE 15 PART-4 Questions

MODUEL15 PART-4
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15.12 Air Systems 15.13 Starting and Ignition Systems 15.14 Engine Indication Systems 15.15
Power Augmentation Systems 15.16 Turbo-prop Engines 15.17 Turbo-shaft engines 15.18
Auxiliary Power Units (APUs)
Module 15, GAS TURBINE ENGINE.

15.12 Air Systems.
Q. 1. Engine anti-ice is taken from the.

turbine.
👉
H.P compressor.
LP compressor. ✓ ANS H.P compressor.
Explanation. Jepperson Gas Turbine Powerplants Page 9-2 refers.
Q. 2. In an axial flow turbine engine, compressor bleed air is sometimes used to aid in cooling
the.
inlet guide vanes.

turbine, vanes, blades, and bearings.
👉
fuel.
👉
✓ ANS turbine, vanes, blades, and bearings. Explanation. NIL.
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Q. 3. If air is taken from the compressor for air conditioning or anti-icing.
thrust will increase EGT will increase.
👉
thrust will decrease EGT will increase.
thrust will decrease EGT will decrease. ✓ ANS thrust will decrease EGT will increase.
Explanation. Air is taken from the H.P compressor hence there is less mass flow.
Q. 4. Turbine case cooling utilizes.

LP compressor air.
👉
fan air.
H.P compressor air. ✓ ANS fan air.
Explanation. Fan air is the coldest in the engine.
Q. 5. Air for anti-icing is taken from the.

accessory Gearbox.
👉
LP compressor.
H.P compressor. ✓ ANS H.P compressor.
Explanation. LP air would not be hot enough.
Q. 6. As air is bled off the engine, EGT will.
remain constant.
👉
decrease.
increase. ✓ ANS increase.
Explanation. Less air, but same fuel equals higher EGT.
Q. 7. The heat absorbed by internal components can be detrimental to thrust and is prevented
by.
reducing fuel flow to reduce internal temperature.

bleeding air off the compressor to heat the components.
👉
bleeding air off the compressor to cool the components.
✓ ANS bleeding air off the compressor to cool the components.
Explanation. Jeppesen Aircraft Gas Turbine Powerplant Page 4-53 refers.
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Q. 8. On a gas turbine engine, thermal wing de-icing system derives air.
👉
👉
via air from the H.P turbine.
through a pressure regulating shut-off valve (P.R.S.O.V).
👉
through a pressure relief system.
✓ ANS through a pressure regulating shut-off valve (P.R.S.O.V).
Explanation. Rolls Royce The Jet Engine Page 150 Refers.
Q. 9. Inlet for cooling air for the first stage turbine blades is fed via the.
blade root.
👉
grill holes.
leading edge of the blade. ✓ ANS blade root.
Explanation. The cooling air is ducted through the turbine disc to the blade root then out into
the airstream through holes in the leading and trailing edges.
Q. 10. Air bleed for an anti-ice system is.

tapped directly off the compressor.
sent through a pressure regulator.
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sent through the air conditioning.
✓ ANS tapped directly off the compressor. Explanation. With this method if the engine is
running then anti-ice air is always available.
Q. 11. With bleed valves open for anti-ice.
thrust is unaffected.
👉 thrust decreases, fuel consumption

thrust decreases, fuel consumption decreases.
thrust decreases, fuel consumption increases. ✓ ANS
decreases. Explanation. NIL.
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, Starting and Ignition Systems.
Q. 1. In the H.E.I.U. the discharge resistors.
allows the capacitors to discharge when the unit is switched off.

allows sufficient voltage to be stored to provide relight facilities up to 55,000 ft.
👉
protects the unit from excessive voltages.
✓ ANS allows the capacitors to discharge when the unit is switched off.
Explanation. NIL.
Q. 2. In the H.E.I.U. the choke.

prolongs the life of the plug.
👉
protects the unit from excessive high voltages.
prolongs the discharge. ✓ ANS prolongs the discharge. Explanation. NIL.
Q. 3. In an electrical starting system, the slow start resistor is short circuited by the.
centrifugal Switch.
👉
time switch.
overspeed switch. ✓ ANS centrifugal Switch. Explanation. NIL.
Q. 4. The advantage of an air starter system is.
it provides a more rapid start.
👉
it is light, simple and economical.
there is no risk of engine fire during starting. ✓ ANS it is light, simple and economical.
Explanation. Jeppesen A&P Technician Powerplant Book Page 8-49 'Air starters weigh about
one-fifth the wieght of a comparable electric starter. This gives air turbine starters a high
power-to-wieght ratio. because of this, pneumatic starters are used almost exclusively on
commercial jet aircraft.
Q. 5. An advantage of a gas turbine starter is.
it provide high power for low weight.

it does not require external connections.
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it uses a low volatile fuel.
👉
✓ ANS it provide high power for low weight. Explanation. NIL.
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Q. 6. If the engine fails to light-up, the starter cycle is canceled by.
a centrifugal switch.
👉
a low pressure relay.
a time switch. ✓ ANS a time switch.
Explanation. NIL.
Q. 7. For starting the engine, the H.P cock should be initially.

in a position which depends on the fuel system.
👉
open.
closed. ✓ ANS closed.
Explanation. NIL.
Q. 8. On light up, the gas temperature will.
rise slowly.
rise rapidly, then fall as RPM increases to idle.
👉
rise rapidly.
✓ ANS rise rapidly, then fall as RPM increases to idle. Explanation. NIL.
Q. 9. Self sustaining RPM means that.

The engine can accelerate to full power in under 5 seconds.
There is sufficient power for ground maneuvering.
The engine will run independently of external help.
✓ ANS 👉 The engine will run independently of external help.

Explanation. NIL.
Q. 10. A 'hot start' with excessive temperatures may be caused by.

wrong grade of fuel.
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throttle partly open.
high electrical power supply. ✓ ANS throttle partly open. Explanation. NIL.
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Q. 11. A dry motoring cycle would be required to.
clear the engine after a wet start.
👉 clear the engine after a wet start. Explanation.

check engine run down time.
check the operation of the igniters. ✓ ANS
NIL.
Q. 12. What type of turbine blade is most commonly used in air starter motors?.
Reaction.
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Impulse.
Impulse-reaction. ✓ ANS Impulse. Explanation. NIL.
Q. 13. Ignitor plugs are cleaned by.

compressed air and brushing lightly with soft brush.
light sand blasting.
👉
steel wool.
✓ ANS compressed air and brushing lightly with soft brush.
Q. 14. An H.E.I.U works by.

a discharging capacitor.
ac busbar.
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a contact breaker.
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✓ ANS a discharging capacitor.
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Q. 15. When is ignition used?.

For relight and start up.
For continuous relight.
👉
At high altitudes.
✓ ANS For relight and start up.
Q. 16. An ignitor plug for a large gas turbine takes the form of a.
glow' plug.
👉
sparking plug.
surface discharge plug. ✓ ANS surface discharge plug.
Q. 17. The spark in the High Energy igniter is supplied by.

a capacitor.
👉
a contact circuit breaker.
the AC busbar. ✓ ANS a capacitor.
Explanation. Jeppesen Gas Turbine Powerplant Page11-4 refers.
Q. 18. Self sustaining speed is.

V1 speed.
the RPM at which the engine continues without external assistance.
👉
take off velocity.
✓ ANS the RPM at which the engine continues without external assistance.
Explanation. After the starter has cut out and the RPM and TGT have stabilised.
Q. 19. During normal running conditions.

combustion is intermittently supported by ignition.
👉 combustion is self supporting

combustion is self supporting
combustion is continuously supported by ignition. ✓ ANS
Explanation. Rolls Royce The Jet Engine page 37 refers.
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Q. 20. High energy ignition is required because of the.
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high flash point of the fuel.
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absorbed moisture content.
low flash point of the fuel. ✓ ANS high flash point of the fuel.
Explanation. Jeppesen Gas Turbine Powerplants Page 7-1 refers.
Q. 21. In the H.E.I.U. the discharge resistors.
allow sufficient voltage to be stored to provide relight facilities up to 55,000 ft.

allow the capacitors to discharge when the unit is switched off.
👉
protect the unit from excessive voltages.
✓ ANS allow the capacitors to discharge when the unit is switched off.
Explanation. Rolls Royce The Jet Engine page 129 refers
Q. 22. The rate of discharge of a H.E.I.U. is.
4 discharges per revolution.
👉 60 - 100 per minute. Explanation.

60 - 100 per second.
60 - 100 per minute. ✓ ANS NIL.
Q. 23. Why do turbine engine ignition systems require high energy?.

Because the applied voltage is much greater.
To ignite the fuel under conditions of high altitude and high temperatures.
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To ignite the fuel under conditions of high altitude and low temperatures.
✓ ANS To ignite the fuel under conditions of high altitude and low temperatures.
Explanation. Jeppesen A&P Technician Propulsion Textbook 8-102.
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Q. 24. The type of ignition system used on most turbine aircraft engines is.
low tension.
capacitor discharge.
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high resistance.
✓ ANS capacitor discharge.
Q. 25. A safety feature usually employed in pneumatic starters that is used to prevent the
starter from reaching burst speed if inlet air does not terminate on schedule is the.
stator nozzle design that chokes airflow and stabilizes turbine wheel speed.
drive shaft shear point.
👉
spring coupling release.
✓ ANS stator nozzle design that chokes airflow and stabilizes turbine wheel speed.
Q. 26. A safety feature usually employed in pneumatic starters that is used if the clutch does
not release from the engine drive at the proper time during start is the.
spring coupling release.
👉
drive shaft shear point.
flyweight cutout switch. ✓ ANS flyweight cutout switch.
Q. 27. Airflow to the pneumatic starter from a ground unit is normally prevented from causing
starter overspeed during engine start by.
a preset timed cutoff of the airflow at the source.
👉
stator nozzle design that chokes airflow and stabilizes turbine wheel speed speed.
activation of a flyweight cutout switch. ✓ ANS activation of a flyweight cutout switch.
Q. 28. Air turbine starters are generally designed so that reduction gear distress or damage
may be detected by.
inspection of a magnetic chip detector.
characteristic sounds from the starter assembly during engine start.
breakage of a shear section on the starter drive shaft.
✓ ANS 👉 inspection of a magnetic chip detector. Explanation. Jeppesen A&P Technician

Propulsion Textbook 8-51.
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Q. 29. Inspection of pneumatic starters by maintenance technicians usually includes checking
the.
stator and rotor blades for FOD.

oil level and magnetic drain plug condition.
👉
rotor alignment.
✓ ANS oil level and magnetic drain plug condition. Explanation. Jeppesen A&P Technician
Propulsion Textbook 8-51.
Q. 30. Pneumatic starters are usually designed with what types of airflow impingement
systems?.
Radial inward flow turbine and axial-flow turbine.

Centrifugal compressor and axial-flow compressor.
👉
Double entry centrifugal outward flow and axial-flow turbines.
✓ ANS Radial inward flow turbine and axial-flow turbine.

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Q. 31. A clicking sound heard at engine coast-down in a pneumatic starter incorporating a
👉
sprag clutch ratchet assembly is an indication of.
👉
👉
gear tooth and/or pawl damage.
one or more broken pawl springs.
👉
the pawls re-contacting and riding on the ratchet gear.
✓ ANS the pawls re-contacting and riding on the ratchet gear.
Q. 32. The primary advantage of pneumatic (air turbine) starters over comparable electric
starters for turbine engines is.
high power-to-weight ratio.
reduction gearing not required.
👉
a decreased fire hazard.
✓ ANS high power-to-weight ratio. Explanation. NIL.
Q. 33. The purpose of an under current relay in a starter-generator system is to.

keep current flow to the starter-generator under the circuit capacity maximum.
disconnect power from the starter-generator and ignition when sufficient engine speed is
reached.
👉
provide a backup for the starter relay.
✓ ANS disconnect power from the starter-generator and ignition when sufficient engine
speed is reached.
Q. 34. How does the ignition system of a gas turbine engine differ from that of a reciprocating
engine?.
Magneto to engine timing is not critical.

One igniter plug is used in each combustion chamber.
A high energy spark is required for ignition. ✓ ANS👉A high energy spark is required for
ignition.
Q. 35. In a gas turbine engine D.C capacitor discharge ignition system, where are the high
voltage pulses formed?.
At the rectifier.
At the triggering transformer.
👉
At the breaker.
👉
✓ ANS At the triggering transformer.
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👉
Q. 36. Igniter plugs used in turbine engines are subjected to high intensity spark discharges
and yet they have a long service life because they.
operate at much lower temperatures.
are not placed directly into the combustion chamber.
do not require continuous operation. ✓ ANS 👉

do not require continuous operation.
Q. 37. Great caution should be exercised in handling damaged hermetically sealed turbine
engine igniter transformer units because.
some contain toxic chemicals.
some contain radioactive material.
👉
compounds in the unit may become a fire or explosion hazard when exposed to the air. ✓ ANS
some contain radioactive material.
Q. 38. Generally, when removing a turbine engine igniter plug, in order to eliminate the
possibility of the technician receiving a lethal shock, the ignition switch is turned off and.
disconnected from the power supply circuit.
the transformer exciter input lead is disconnected and the center electrode grounded to the
engine after disconnecting the igniter lead from the plug and waiting the prescribed time.
the igniter lead is disconnected from the plug and the center electrode grounded to the engine
👉
after disconnecting the transformer-exciter input lead and waiting the prescribed time.
✓ ANS the igniter lead is disconnected from the plug and the center electrode grounded to
the engine after disconnecting the transformer-exciter input lead and waiting the prescribed
time.
Explanation. NIL.
Q. 39. What is the first engine instrument indication of a successful start of a turbine engine?.
A rise in the engine fuel flow.
A rise in oil pressure.
A rise in the exhaust gas temperature.
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✓ ANS 👉 A rise in the exhaust gas temperature. Explanation. NIL.
Q. 40. H.E.I.U ignitor plugs receive their electrical supply from.

discharge inductor.
👉
starter system electrical circuit.
discharge capacitor. ✓ ANS discharge capacitor.
Explanation. Rolls Royce The Jet Engine Page 129.
Q. 41. An H.E.I.U is rated in.

Joules.
👉
Watts.
Amps. ✓ ANS Joules.
Explanation. Jeppesen Aircraft Gas Turbines Powerplant Page 11-5 to 11-7 refers.
Q. 42. A glow plug operates.

manually.
by heat action.
👉
electrically.
✓ ANS by heat action.
Explanation. The extreme heat of the plug ignites the fuel. It is powered by electricity. See
Jeppesen Aircraft Gas Turbines page 11-9.
Q. 43. The resistor in a D.C. starter motor.

prevents over speed.
👉
prevents current surge when motor is at low rpm.
👉
👉
👉
used when D.C. motor fails.
✓ ANS prevents current surge when motor is at low rpm.
Q. 44. Where does the high voltage type turbine ignition receive its voltage pulse from?.
Primary windings.
👉
Rectifier.
Trigger transformer. ✓ ANS Primary windings.
Explanation. Rolls Royce the jet engine Fig 11-12 shows an AC system. this uses a
transformer to generate the high voltage at the discharge gap.
Q. 45. On a gas turbine engine DC starting circuit, if there is an open circuit on the contact of
the over speed relay.
starter motor will stop only when starter switch selected off.
starter motor will continue to run for 30 sec and then stop.
no power supply is connected to the starter motor.
✓ ANS 👉 no power supply is connected to the starter motor.

Explanation. Refer Fig 11-3 Rolls Royce The Jet engine. The main relay cannot close if the
overspeed relay is open.
Q. 46. The field of the D.C. starter motor used on gas turbine engine
is.
series only.
👉
shunt or compound.
series or compound. ✓ ANS series or compound.
Explanation. Aircraft electrical systems E.H.J Pallett 3rd edition page 154 refers.
Q. 47. When 'blow out' is selected on the Gas Turbine Engine starting circuit.
the starter motor is stopped when starter switch selected off or when the timer switch cuts out.
the over-speed relay will de-energise the starter circuit.
👉
ignition is continuously on.
✓ ANS the starter motor is stopped when starter switch selected off or when the timer
switch cuts out.
Explanation. Refer Fig 11-3 Rolls Royce The Jet Engine. The blow out circuit is used to blow
out any jet pipe fire. In this mode there is no ignition or fuel hence the starter cannot overspeed.
👉
Q. 48. After an unsuccessful start of an engine.
👉
👉
the engine has to be left for some time before another start.
unburnt fuel can be drained from fuel drainage lines.
👉
unburnt fuel can be evacuated by motoring the engine with H.P cock closed.
✓ ANS unburnt fuel can be evacuated by motoring the engine with H.P cock closed.
Explanation. On normal shutdowns combustors and fuel manifolds are drained through the
drain manifold. After an unsuccessful start there will be fuel

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throughout the hot section. Hence a dry run is needed to purge the engine.
Q. 49. A glow plug may be used in place of a spark plug on.

low temperature engines.
👉
large engines.
small engines. ✓ ANS small engines.
Explanation. Jeppesen Aircraft Gas Turbine Powerplants Page 11-9 refers to the PW PT6 as
an example of a smaller engine.
Q. 50. When an engine being started by an air starter reaches self sustaining speed.
the motor is disconnected by the flyweight cut out switch.
the starter valve is disconnected by the fly weight cut-out switch in the air starter.
👉
the motor is disconnected by the pilot.
✓ ANS the starter valve is disconnected by the fly weight cut-out switch in the air starter.
👉
Explanation. Jeppesen Aircraft Gas Turbine Powerplants Page 10-9 refers.
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👉
Q. 51. When reconnecting a H.E.I.U , which cable must be reconnected first?.
It makes no difference.
👉
L.T before H.T.
H.T before L.T. ✓ ANS H.T before L.T.
Explanation. This is the reverse of disconnecting, when L.T is isolated and then disconnected
first.
Q. 52. An aircraft flying through heavy rain may use, as a precaution.

airframe deicing.
👉
engine intake deicing.
continuous ignition. ✓ ANS continuous ignition.
Explanation. Continuous ignition is used in case of flame out caused by the inclement
weather.
Q. 53. The starter light is on during a start cycle (low voltage electrical starter).
Indicates electrical power is flowing to the starter.
If the light stays on after 30 seconds action is required.
👉
This is normal for 30 seconds, take no action.
✓ ANS If the light stays on after 30 seconds action is required.
Explanation. See the Rolls Royce Jet engine low voltage starter system on page 123. The
indicator light indicates power to the igniter. The Full current time switch cuts out the circuit after
a period of time.
Q. 54. A D.C starter motor disconnects due to.
current decreasing switching off an overspeed relay.
current increasing switching off an overspeed relay.
a centrifugal switch that acts like an overspeed relay.
✓ ANS 👉 current decreasing switching off an overspeed relay.

Explanation. Same starter circuit reference as above. As the starter accelerates drawn current
reduces and causes the overspeed relay to drop out.
👉
Q. 55. What is the purpose of the current limiting resistor in a starter circuit?.
👉
👉
To prevent the starter from over speeding in the final phase of starting.
👉
To provide overall control of the the speed of the starter.
To prevent an initial current surge. ✓ ANS To prevent an initial current surge.
Explanation. The starter motor is protected from excessive current until the timer shorts out
the resistor. See RR the jet engine page 123.
Q. 56. On a low energy dual ignition system (<3 joules), if a relight is necessary.
it occurs automatically.
👉
the pilot selects both ignitors.
the pilot selects one of the two ignitors. ✓ ANS the pilot selects both ignitors.
Explanation. Normal low/high systems have a choice of low or high energy ignition with high
being used for relight. In these systems the pilot can choose 1, 2 or both.
, Engine Indication Systems.
Q. 1. The compensation device on an E.G.T system must be re-calibrated after.

each time a part of the system is replaced.

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👉
does not need calibration.
manufacture and overhaul. ✓ ANS does not need calibration.
Explanation. The compensation device is an automatic device Page 140 Rolls Royce book
👉
refers.
👉
👉
Q. 2. When testing an E.G.T system.
the O.A.T is always taken into consideration.
the O.A.T is neglected.
O.A.T is only taken into consideration when over20°C.
✓ ANS 👉 the O.A.T is always taken into consideration. Explanation. To test the system the
test set has to trimmed for ambient temperature, as the system when in operation is adjusted for
ambient temperature by the compensating resistor. This is clearly stated in the B 737 AMM.
Q. 3. What is the Engine Pressure Ratio (E.P.R.) used for?.

To limit the maximum exhaust gas temperature.
👉
To indicate the thrust produced by the engine.
As a cross check for minimum acceptable thrust. ✓ ANS To indicate the thrust produced by
the engine. Explanation. NIL.
Q. 4. What happens when bulb type thermometer resistive element goes open circuit?.
Reads less than ambient.
👉
No reading given.
Reads more than ambient. ✓ ANS Reads more than ambient. Explanation. NIL.
Q. 5. On an E.G.T thermocouple system, the hot junction.

is placed up stream of the combustion chamber.
is placed in cockpit.
is placed downstream of the combustion chamber.
✓ ANS 👉 is placed downstream of the combustion chamber. Explanation. NIL.
Q. 6. On an RPM system using a synchronous generator, the pointer is deflected by.

a potentiometer.
👉
a Wheatstone bridge.
an AC servomotor. ✓ ANS an AC servomotor.
Q. 7. Torque pressure is usually read from a.
👉
torque meter.
👉
👉
direct reading pressure gauge.
👉
tension gauge.
✓ ANS direct reading pressure gauge.
Explanation. Jepperson Gas Turbine Powerplants Page12-21 refers.
Q. 8. The drag cup in a tacho-generator is balanced by.

calibrated hairspring.
adjustable counterbalance weights.
👉
adjustment screw.
✓ ANS calibrated hairspring.
Q. 9. Fuel flow indication is taken from.

after the H.P pump.
after either H.P Pump or LP Pump.
👉
after the LP pump.
✓ ANS after either H.P Pump or LP Pump.
Explanation. Vane type flowmeters are usually in the LP Supply. Integrated flowmeters in the
H.P supply.
Q. 10. What power is required for E.G.T gauge indication?.

No power - it is self generating.
115V AC.
👉
28V DC.
✓ ANS No power - it is self generating.
Explanation. Jeppesen Gas Turbine Powerplants Page 12-5 Refers.
Q. 11. A Bourdon tube instrument may be used to indicate.

position and quantity.
👉
pressure and temperature.
pressure, temperature, position and quantity. ✓ ANS pressure and temperature.
Explanation. NIL.
Q. 12. What instrument on a gas turbine engine should be monitored to minimize the
possibility of a 'hot' start?.
👉
👉
👉
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RPM indicator.
Turbine inlet temperature.
👉
Torquemeter.
✓ ANS Turbine inlet temperature.
Explanation. Jeppesen A&P Powerplant Textbook 4-5.
Q. 13. oil temperature thermocouples are usually constructed of.

iron constantan.
👉
alumel constantan.
chromel alumel. ✓ ANS iron constantan. Explanation. NIL.
Q. 14. The RPM indication of a synchronous AC motor tachometer is governed by the

generator.
current.
frequency.
👉
voltage.
✓ ANS frequency. Explanation. NIL.
Q. 15. Instruments that measure relatively high fluid pressures, such as oil pressure gauges,
are usually what type?.
Bourdon tube.
👉
Vane with calibrated spring.
Diaphragm or bellows. ✓ ANS Bourdon tube. Explanation. NIL.
👉
👉
👉
Q. 16. Instruments that provide readings of low or negative pressure, such as manifold pressure
gauges, are usually what type?.
Diaphragm or bellows.
Vane with calibrated spring.
👉
Bourdon tube.
✓ ANS Diaphragm or bellows. Explanation. NIL.
Q. 17. In what units are gas turbine engine tachometers calibrated?.

Percent of engine pressure ratio.
Percent of engine RPM.
👉
Actual engine RPM.
✓ ANS Percent of engine RPM.
Q. 18. In a turbine engine, where is the turbine discharge pressure indicator sensor located?.
At a location in the exhaust cone that is determined to be subjected to the highest pressures.
👉
Immediately aft of the last turbine stage.
At the aft end of the compressor section. ✓ ANS Immediately aft of the last turbine stage.
Explanation. NIL.
Q. 19. The exhaust gas temperature (E.G.T ) indicator on a gas turbine engine provides a
relative indication of the.
turbine inlet temperature.
temperature of the exhaust gases as they pass the exhaust cone.
👉
exhaust temperature.
✓ ANS turbine inlet temperature.
Q. 20. Engine pressure ratio is determined by.
dividing engine inlet total pressure by turbine outlet total pressure.

multiplying engine inlet total pressure by turbine outlet total pressure.
👉
dividing turbine outlet total pressure by engine inlet total pressure.
✓ ANS dividing turbine outlet total pressure by engine inlet total pressure.
Explanation. NIL.
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👉
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Q. 21. A red triangle, dot, or diamond mark on an engine instrument face or glass indicates.
the maximum limit for high transients such as starting.
a restricted operating range.
👉
the maximum operating limit for all normal operations.
✓ ANS the maximum limit for high transients such as starting.
Q. 22. What is the primary purpose of the tachometer on an axial compressor turbine engine?.
Monitor engine RPM during cruise conditions.
Monitor engine RPM during starting and to indicate overspeed conditions.

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👉
It is the most accurate instrument for establishing thrust settings under all conditions.
✓ ANS Monitor engine RPM during starting and to indicate overspeed conditions.
Q. 23. Engine pressure ratio is the total pressure ratio between the.
front of the engine inlet and the aft end of the compressor.
front of the compressor and the rear of the turbine.
👉
aft end of the compressor and the aft end of the turbine.
✓ ANS front of the compressor and the rear of the turbine.
👉
👉
👉
Q. 24. On an aircraft turbine engine, operating at a constant power, the application of engine
anti-icing will result in.
an increase in E.P.R.
noticeable shift in E.P.R.
👉
a false E.P.R reading.
✓ ANS noticeable shift in E.P.R.
Q. 25. The indicator of a tachometer system is responsive to change in.

voltage.
👉
frequency.
current flow. ✓ ANS frequency.
Q. 26. The fuel flow indication data sent from motor driven impeller and turbine, and motorless
type fuel flow transmitters is a measure of.
fuel mass flow.
👉
fuel volume flow.
engine burner pressure drop. ✓ ANS fuel mass flow.
Q. 27. In addition to fuel quantity, a computerized fuel system (C.F.S) with a totalizer indicator
provides indication of how many of the following?.
Fuel flow rate, Fuel used since reset or initial start up, Fuel time remaining at current power
setting.
Fuel flow rate, Fuel used since reset or initial start up, Fuel time remaining at current power
setting, Fuel temperature.
👉
Fuel flow rate, Fuel used since reset or initial start up, Fuel temperature.
✓ ANS Fuel flow rate, Fuel used since reset or initial start up, Fuel time remaining at current
power setting.
Q. 28. The fuel flow indicator rotor and needle for a motor impeller and turbine indicating system
is driven by.
direct coupling to the motor shaft.
👉
an electrical signal.
a mechanical gear train. ✓ ANS an electrical signal.
👉
👉
👉
Q. 29. Motor driven impeller and turbine fuel flow transmitters are designed to transmit data.
using aircraft electrical system power.
mechanically.
👉
by fuel pressure.
✓ ANS using aircraft electrical system power. Explanation. NIL.
Q. 30. What unit in a tachometer system sends information to the indicator?.

The two phase AC generator.
The three phase AC generator.
👉
The synchronous motor.
✓ ANS The three phase AC generator. Explanation. Jeppesen Aircraft Gas Turbine
Powerplants 12-13.
Q. 31. Engine oil temperature gauges indicate the temperature of the oil.
entering the oil cooler.
👉
entering the engine.
in the oil storage tank. ✓ ANS entering the oil cooler.
Explanation. Rolls Royce book fig 8-7.

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Q. 32. Thermocouple leads.
👉
may be repaired using solderless connectors.
👉
👉
are designed for a specific installation and may not be altered.
👉
may be installed with either lead to either post of the indicator.
✓ ANS are designed for a specific installation and may not be altered.
Explanation. NIL.
Q. 33. Why do helicopters require a minimum of two synchronous tachometer systems?.

One indicates engine RPM and the other tail rotor RPM.
One indicates main rotor RPM and the other tail rotor RPM.
👉
One indicates engine RPM and the other main rotor RPM.
✓ ANS One indicates engine RPM and the other main rotor RPM.
Explanation. NIL.
Q. 34. If the thermocouple leads were inadvertently crossed at installation, what would the
E.G.T gauge pointer indicate?.
Moves off scale on the high side of the meter.
👉
Moves off scale on the zero side of the meter.
Normal temperature for prevailing condition. ✓ ANS Moves off scale on the zero side of the
meter. Explanation. NIL.
Q. 35. A common type of electrically operated oil temperature gauge utilizes.

either a wheatstone bridge or ratiometer circuit.
a thermocouple type circuit.
👉
vapour pressure and pressure switches.
✓ ANS either a wheatstone bridge or ratiometer circuit. Explanation. NIL.
Q. 36. The indication on a thermocouple-type E.G.T indicator is produced by.

resistance changes in two dissimilar metals.
a difference in the voltage between two dissimilar metals.
a current generated by the temperature difference between dissimilar metal hot and cold
👉
junctions.
✓ ANS a current generated by the temperature difference between dissimilar metal hot and
cold junctions.
Explanation. NIL.
Q. 37. What is the Engine Pressure Ratio (E.P.R) used to indicate?.

The power produced by the engine.
The thrust produced by the engine.
👉
👉
👉
As a cross check for minimum acceptable thrust. ✓ ANS 👉 The thrust produced by the engine.
Explanation. Normally used on High Bypass Engines.
Q. 38. Where is Turbine Outlet Temperature (T.O.T) measured?.

Upstream of the turbine.
👉
Downstream of the turbine.
In the combustion chamber. ✓ ANS Downstream of the turbine.
Explanation. It can be in the jet pipe or more normally today in between turbine stages or even
within NGV's.
Q. 39. A thermocouple indicator is basically a.
milliammeter.
👉
millivoltmeter.
milliohmeter. ✓ ANS millivoltmeter.
Explanation. A thermocouple generates an E.M.F between hot and cold junction, hence the
gauge is a millivoltmeter.
Q. 40. A thermocouple indicator is connected to the.
cold junction.
hot junction.
👉
difference between the hot junction and the cold junction.
✓ ANS cold junction.
Explanation. Pallett Aircraft Instruments and Integrated Systems Page 362 Refers.
Q. 41. Thrust in a high bypass fan engine is indicated by.

N3 RPM or P1/P4 ratio.
👉
N1 RPM or N3 RPM.
N1 RPM or E.P.R. ✓ ANS N1 RPM or E.P.R.
Explanation. RR and P&W tend to use E.P.R. GE use N1.
👉
👉
👉
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Q. 42. How is the N1 and N2 measured on a triple spool engine?.

Tachometer connected to the internal gearbox.
👉
Tachometer connected to the external gearbox.
Pulse type speed probes. ✓ ANS Pulse type speed probes.
Explanation. Jeppesen Gas Turbine Powerplants Page 12-16 refer. Fig 12-10B shows the
system used on Rolls Royce triple spool engines.
Q. 43. Modern oil pressure servo transmitters sense.
absolute pressure.
👉
H.P oil pressure.
differential pressure. ✓ ANS differential pressure.
Explanation. Jeppesen Gas Turbine Powerplants Page 12-28 refer.
Q. 44. E.G.T thermocouples are usually made of.
nickel and platinum.
👉
chromel and platinum.
chromel and alumel. ✓ ANS chromel and alumel.
Explanation. Jeppesen Gas Turbine Powerplants Page 12-4 refer.
Q. 45. Thrust in a high bypass engine is indicated by measuring.

N3 RPM.
neither of the above, thrust is not indicated in flight.
👉
fuel flow.
✓ ANS neither of the above, thrust is not indicated in flight.
Explanation. The only indication of power in flight is E.P.R or, for a high bypass engine, N1
👉
RPM.
👉
👉
Q. 46. What power supply is required for a thermocouple system to work?.
Alternating current.
👉
Direct current.
Neither of the above. ✓ ANS Neither of the above.
Explanation. Rolls Royce the Jet engine Page 139 refers.
Q. 47. In a thermocouple temperature sensing system, what is the purpose of the compensating
resistor?.
To correct for varying ambient temperatures at the hot junction.
To correct for varying ambient temperatures at the cold junction.
To standardise the reading for different engine types.
✓ ANS 👉 To correct for varying ambient temperatures at the cold junction.

Q. 48. In a tachometer generator.

the frequency output is inversely proportional to engine speed.
frequency output is proportional to engine speed.
👉
the frequency output is constant.
✓ ANS frequency output is proportional to engine speed.
Explanation. Pallett Aircraft Instruments and Integrated Systems P348 refers.
Q. 49. Vibration pick-ups are located.

on both fan and turbine cases.
on the fan/compressor case.
👉
on the turbine case.
✓ ANS on both fan and turbine cases.
Explanation. Can be on one or both, depending upon the engine.
Q. 50. In a capacitive type fuel quantity indicating system the tank units are connected in.
series.
👉
parallel.
series/parallel. ✓ ANS parallel.
Explanation. EHJ Pallett Aircraft Instruments and Integrated Systems page 337 refers.
👉
Q. 51. Torque measurement in a gas turbine engine is.
👉
👉
not always reliable.
👉 required only when the turbine

highly reliable.
required only when the turbine drives a propeller. ✓ ANS
drives a propeller.
Explanation. Rolls Royce The Jet Engine Page 138 refers.

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Q. 52. Vibration signals, when picked up,.

go straight to indicator.
go through half wave rectifier to indicator.
👉
the frequencies are filtered to exclude unwanted frequencies.
✓ ANS the frequencies are filtered to exclude unwanted frequencies.
Explanation. The filters in the Vibro-meter use rotor speed to identify vibration frequencies.
Q. 53. E.G.T is displayed in.

Kelvin.
👉
degrees centigrade.
degrees Fahrenheit. ✓ ANS degrees centigrade.
Explanation. E.G.T is always measured in centigrade.
👉
Q. 54. N2 is taken from.
👉
👉
a speed transducer on the fan rear frame.
👉
a tachometer attached on the N1 gearbox.
a tachometer on the accessory gearbox. ✓ ANS a tachometer on the accessory gearbox.
Explanation. The N2 gearbox is driven by the N2 compressor. A single winding of an alternator
can be used for the speed signal as an alternative to a.
Q. 55. Engine vibration is monitored using.
electromechanical devices.
👉
Fenwall type sensors.
piezoelectric accelerometer. ✓ ANS piezoelectric accelerometer.
Explanation. Piezoelectric devices convert force(from the vibration) to a milli-volt output.
Q. 56. Integrating fuel flow gives.

average fuel flow.
👉
total fuel consumed.
fuel flow and acceleration. ✓ ANS total fuel consumed.
Explanation. An Integrator is incorporated in a fuel flow-meter to give a total fuel used figure.
Q. 57. The gauge on a bulb type temperature indicator shows zero. This could be caused by.
open circuit in the wiring.
👉
temperature bulb going open circuit.
two cables shorting together by the sensor. ✓ ANS two cables shorting together by the
sensor.
Explanation. Pallett Instruments and Integrated systems Page 318 refers. A short will remove
all power from both windings and the pointer will go tominimum scale.
Q. 58. In a thermocouple system, the size of the E.M.F that is produced is a result of.
the difference between the hot and cold junction.
the cold junction only.
👉
the hot junction only.
✓ ANS the difference between the hot and cold junction.
Explanation. The E.M.F is a result of the difference between the 2 junctions.
👉
Q. 59. A ballast resistor is fitted.
👉
👉
in parallel, to give identical readings for all engines.
in series, to give identical resistance values for all engines.
👉
in series, to give identical resistance values to all airframes.
✓ ANS in series, to give identical resistance values to all airframes.
Explanation. NIL.
, Power Augmentation Systems
Q. 1. When reheat is used, E.P.R.

is reduced.
remains constant.
👉
is increased.
✓ ANS remains constant.
Explanation. Rolls Royce The jet engine page 175 states that as P6 increases in the jet pipe
the nozzles are opened to reduce P6 back to its normal value.
Q. 2. When reheat is selected and in operation, the mass gas flow.

decreases.
remains the same.
👉
increases.
✓ ANS remains the same. Explanation. NIL.

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👉
👉
👉
Q. 3. Screech liners in the afterburning jet pipe.
prevent unstable combustion.

prevent cyclic vibrations of large amplitude.
👉
acts as noise suppressors.
✓ ANS prevent cyclic vibrations of large amplitude. Explanation. NIL.
Q. 4. Water methanol for cooling is injected into the.
compressor inlet or outlet.

engine hot zone.
👉
combustion chamber.
✓ ANS compressor inlet or outlet.
Q. 5. On an injection system.
methanol is injected neat.
👉
town water/methanol is injected.
demineralized water/methanol is injected. ✓ ANS demineralized water/methanol is injected.
Q. 6. When using water methanol in an axial flow compressor, it is injected into the.
compressor inlet or burner section.
burner.
👉
intake.
✓ ANS compressor inlet or burner section.
Explanation. Jepperson Gas Turbine Powerplant Fig 7-32.
Q. 7. The main reason for adding methanol to the water is to.

temper the cooling effect of the water to prevent distortion.
👉
supply the additional heat required.
prevent mixture freezing. ✓ ANS prevent mixture freezing.
Q. 8. The primary purpose of water injection is to.
👉
👉
👉
decrease mass airflow.
👉
increase the calorific value of the fuel.
cool the turbine. ✓ ANS cool the turbine.
Explanation. Notice that the answers did not include 'increase mass airflow'. Cooling the
turbine is the primary purpose o=if the water is injected in the combustor outlet manifold.
Q. 9. Water used in a thrust augmentation system should be demineralised to prevent.

blocking the jet.
👉
carbon formation.
fouling the blades and vanes. ✓ ANS fouling the blades and vanes. Explanation. NIL.
Q. 10. The quantity of water usually carried by an aircraft equipped with water injection is
enough for.
three take-offs.
👉
one take-off.
two take-offs. ✓ ANS one take-off.
Explanation. Jeppesen Gas Turbine Powerplants Page 7-41 refers.
Q. 11. Water methanol injection will increase thrust by up to.

A. 70%.
B. 50%.
👉
C. 30%.
✓ ANS 30%.
Explanation. Jeppesen Aircraft Gas Turbine Powerplant page 7-41 shows 10-15% so 30% is
nearest.
Q. 12. Injection of water/methanol into compressor inlet causes.

increase in power due to the burning of methanol alone.
increase in power without the need for burning extra fuel.
👉
increased efficiency of the engine due to reduced icing in the airflow.
✓ ANS increase in power without the need for burning extra fuel.
Explanation. Jeppesen Aircraft gas Turbine Power plant page 7-41 refers.
Q. 13. Reheat is the term used to describe.
👉
adding fuel in the exhaust section.
👉
👉
adding of fuel in the turbine section.
adding of fuel in the compressor section.

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✓ ANS 👉 adding fuel in the exhaust section.

Q. 14. Water/methanol is injected.

at high temperatures.
👉
at high temperature, at high altitudes.
at high temperatures or high altitudes. ✓ ANS at high temperatures or high altitudes.
Explanation. Jeppesen aircraft gas turbine Powerplants Page 7-39 refers.
Q. 15. The reheat ignition system which incorporates a platinum/rhodium element is known
as.
catalytic ignition.
👉
hot-shot ignition system.
spark ignition system. ✓ ANS catalytic ignition.
Explanation. fuel sprayed on to the catalytic element heats up and ignites.
Q. 16. Water or water/methanol injected into the combustion chamber inlet increases.
mass airflow through the turbine.
combustion chamber outlet temperatures.
👉
fuel to air ratio by up to 20%.
👉
👉
✓ ANS 👉 mass airflow through the turbine. Explanation. Jeppesen Gas turbine Power plant
page 7-41 refers.
Q. 17. Methanol is added to water when augmenting thrust in order to.

reclaim lost pressure at the compressor.
increase the density of air entering the compressor.
reclaim lost heat at the turbines. ✓ ANS 👉

reclaim lost heat at the turbines.
Explanation. Methanol burns, but its heat output is low. It's prime purpose is to act as an
antifreeze in the water.
Q. 18. Afterburning is initiated in order to.
heat the exhaust to prevent choking at subsonic gas velocities.
👉
burn off the fuel that is not combusted in the combustion section.
increase the local speed of sound at the jet nozzle. ✓ ANS increase the local speed of
sound at the jet nozzle.
Explanation. A faster SoS allows for greater momentum thrust at the exhaust nozzle.
Q. 19. How is the flame stabilised in the reheat system of a gas turbine engine?.
By creating a greater potential between inlet & jet pipe temperatures.
By ensuring that the gas velocity is greater than the flame velocity.
👉
By ensuring that the flame velocity is greater than the gas velocity.
✓ ANS By ensuring that the gas velocity is greater than the flame velocity.
Explanation. The guttering in the reheat manifolds allows the flame to stabilise at the point.
Q. 20. During operation of the engine equipped with water injection system, the metering of the
coolant to the system is.
selected by the pilot.
👉
due to atmospheric pressure.
due to altitude change. ✓ ANS selected by the pilot.
Explanation. Water injection is used on take off as required by the pilot.
Q. 21. Water methanol injection is used.

at high altitude take off conditions only.
at a combination of higher than normal air temperatures and high altitude take off conditions.
👉
at higher than normal ambient air temperatures only.
👉
👉
✓ ANS 👉 at higher than normal ambient air temperatures only.
Explanation. Water Methanol adds to the weight of the air thus compensating for reduced
density.
, Turbo-prop Engines
Q. 1. A free turbine is usually found on a.
turbo-jet.
👉 turbo prop.
turbo-fan.
turbo prop. ✓ ANS
Explanation. NIL.
Q. 2. A free turbine is.

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not directly connected to the power output shaft.

connected directly to the propeller and compressor.
connected directly to the power output shaft. ✓ ANS 👉

connected directly to the power output
shaft. Explanation. Rolls Royce The Jet Engine page 5 refers.
👉
👉
👉
Q. 3. The fuel flow in a turboprop engine within the constant speed range is controlled.
automatically.
manually.
👉
No Control.
✓ ANS automatically.
Explanation. Once the power lever has set the gas generator RPM it is controlled
automatically to maintain the constant speed.
Q. 4. Torque measurement is taken from the.
reduction gearbox.
👉
prop shaft.
free turbine shaft. ✓ ANS reduction gearbox.
Q. 5. Electrical propeller de-icing pads are.
at the root.
👉
at the tip.
on the trailing edge. ✓ ANS at the root.
Explanation. On the leading edge from the root outward.
Q. 6. Fuel trimming on a turboprop engine is.
pilot controlled.
governor controlled.
👉
automatic.
✓ ANS governor controlled.
Q. 7. What controls the fuel trimmer on a turboprop engine?.

The blade angle.
Propeller Control Unit.
👉
Engine Speed Governor.
✓ ANS Engine Speed Governor.
👉
👉
👉
Q. 8. What is the purpose of the reduction gear on a propeller driven engine?.
To maintain a constant propeller blade speed.
To enable torque measurement.
👉
To prevent the propeller tips reaching the speed of sound.
✓ ANS To prevent the propeller tips reaching the speed of sound.
Explanation. Reduction ratios vary between 13.5 :1 and 10:1.
Q. 9. If an E.P.R gauge is installed on turbofans as a measure of power output, what is used

on a turboprop?.
E.P.R gauge.
👉
Torque-meter.
Thermocouples. ✓ ANS Torque-meter.
Explanation. Torque is used because it is measuring the resistance to rotation of the propeller,
which is turned by the power of the engine.
Q. 10. What type of reduction gear is used on most turboprop modern engines?.
Helical cut parallel spur gears.
👉
Epicyclic reduction gear.
Straight cut parallel spur gears. ✓ ANS Epicyclic reduction gear.
Explanation. Epicyclic gearing is essential to enable the very large torque to be safely
absorbed.
, Turbo-Shaft Engines.
Q. 1. A turbo-shaft engine has.

a mechanical connection between compressor and turbine.
a power shaft which is not connected to the compressor.
👉
none of the above.
✓ ANS a power shaft which is not connected to the compressor.
👉
👉
👉
study material
Q. 2. On a twin spool turbo-shaft engine, the free turbine is connected to the.

output gearbox.
L.P gearbox.
👉
H.P gearbox.
✓ ANS output gearbox.
Explanation. The output gearbox will normally contain a reduction gear system and torque
measuring equipment.
Q. 3. In the majority of helicopters, the thrust generated by the gas generator is absorbed by
the.
L.P turbine.
Free power turbine.
👉
H.P turbine.
✓ ANS Free power turbine.
Explanation. The power turbine drives a reduction/rotor transmission gearbox.
, Auxiliary Power Units (APUs).
Q. 1. An A.P.U has.
automatically controlled thrust and is self contained.
👉
variable speed and is self contained.
constant speed and is self contained. ✓ ANS constant speed and is self contained.
Explanation. Jepperson Gas Turbine Powerplants Page 7-26.
👉
👉
👉
Q. 2. An A.P.U shut down is initiated by.
high oil pressure, fire warning, hot oil temperature.
low oil pressure, fire warning, hot oil temperature.
👉
low oil pressure, fire warning.
✓ ANS low oil pressure, fire warning, hot oil temperature.
Explanation. Honeywell 331-200 A.P.U handbook refers.
Q. 3. An A.P.U start cycle is completed at.
100% RPM.
👉
75% RPM.
95% RPM. ✓ ANS 95% RPM.
Explanation. Jeppesen Aircraft Powerplant Page 7- 25 refers.
Q. 4. An A.P.U power lever is located.

behind the throttles.
at the Flight Engineer Station.
👉
An A.P.U is fully automatic and does not require a power lever.
✓ ANS An A.P.U is fully automatic and does not require a power lever.
Explanation. Jeppesen Aircraft Powerplant Page 7- 23.
Q. 5. An A.P.U consists of.

a power compressor and load compressor.
a power compressor and directly connected turbine.
👉
a load compressor and free turbine.
✓ ANS a power compressor and load compressor. Explanation. The power compressor
generates the pressure to drive the system, the load compressor supplies air to the aircraft
pneumatic system.
Q. 6. When necessary, A.P.U engine cooling before shutdown may be accomplished by.
closing the bleed air valve.
👉
opening the bleed air valve.
unloading the generator(s). ✓ ANS closing the bleed air valve.
👉
👉
👉
Q. 7. Frequently, an aircraft's auxiliary power unit (A.P.U) generator.
is identical to the engine-driven generators.
has a higher load capacity than the engine-driven generators.
👉
supplements the aircraft's engine-driven generators during peak loads.
✓ ANS is identical to the engine-driven generators. Explanation. Jeppesen A&P
Technician Propulsion Textbook 3-36.
Q. 8. Fuel scheduling during A.P.U start and under varying pneumatic bleed and electrical
loads is maintained.
automatically by the A.P.U fuel control system.
manually through power control lever position.
Jeppesen A&P Technician Propulsion Textbook 3-37.
✓ ANS 👉 automatically by the A.P.U fuel control system. Explanation. NIL.

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Q. 9. An A.P.U is usually rotated during start by.
a pneumatic starter.
👉
a turbine impingement system.
an electric starter. ✓ ANS an electric starter. Explanation. NIL.
👉
👉
👉
Q. 10. Usually, most of the load placed on an A.P.U occurs when.
the bleed air valve is opened.
👉
an electrical load is placed on the generator(s).
the bleed air valve is closed. ✓ ANS the bleed air valve is opened.
Q. 11. The function of an A.P.U air inlet plenum is to.
stabilize the pressure of the air before it enters the compressor.

increase the velocity of the air before entering the compressor.
👉
decrease the pressure of the air before entering the compressor. .
✓ ANS stabilize the pressure of the air before it enters the compressor.
Q. 12. In a large commercial passenger transport aircraft the A.P.U supplies.

pneumatics and electrics.
electrics.
👉
pneumatics.
✓ ANS pneumatics and electrics.
Explanation. Jeppesen Aircraft Powerplant Page 7- 25.
Q. 13. When in operation, the speed of an A.P.U.
remains at or near rated speed regardless of the load condition.

remains at idle and automatically accelerates to rated speed when placed under load.
👉
is controlled by a cockpit power lever.
✓ ANS remains at or near rated speed regardless of the load condition.
Q. 14. Generally, when maximum A.P.U shaft output power is being used in conjunction with
pneumatic power.
electrical loading will be automatically modulated to maintain a safe E.G.T.
temperature limits and loads must be carefully monitored by the operator to maintain a safe
E.G.T.
👉
pneumatic loading will be automatically modulated to maintain a safe E.G.T.
✓ ANS pneumatic loading will be automatically modulated to maintain a safe E.G.T.
👉
👉
👉
Q. 15. For an A.P.U to run 'unmanned' it must be equipped with.
an automatic fire extinguishing system.
both an audible fire warning and an automatic fire extinguishing system.
👉
an audible fire warning.
✓ ANS both an audible fire warning and an automatic fire extinguishing system.
Explanation. The audible warning is external and internal and auto fire extinguishing (when
the engines are not running) is normal.
Q. 16. An A.P.U is.

a self contained constant speed gas turbine engine.
👉
a reserved engine in case of a main engine failure.
a self contained variable speed gas turbine engine. ✓ ANS a self contained constant speed
gas turbine engine.
Explanation. Jeppesen Aircraft Gas Turbine Powerplant Page 7-24 refers.
Q. 17. When the A.P.U is running and pneumatics are on.

bleed valve is closed, surge valve is open.
👉
bleed valve is open, surge valve is closed.
bleed valve is open, surge valve is modulating. ✓ ANS bleed valve is open, surge valve is
closed. Explanation. NIL.
Q. 18. When is the A.P.U at its greatest load?.
With generator loads on line.

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👉
👉
👉
With bleeds closed.

With bleeds open and with generator loads on line.
✓ ANS 👉 With bleeds open and with generator loads on line.

Explanation. Modern A.P.U's supply pneumatics and electrical power.
Q. 19. Auxiliary power units provide.

hydraulic and electrical power.
👉
pneumatic and electrical power.
hydraulic and pneumatic power. ✓ ANS pneumatic and electrical power.
Explanation. Electrical power is normally available up to the service ceiling with pneumatics up
to about 17000 ft (Boeing B-757/767).
Q. 20. When starting an A.P.U what would the normal duty cycle be on a
modern aircraft?.
6 attempted starts per half hour with 5 minutes between attempts.
3 attempted starts per hour with 5 minutes between each attempt.
👉
6 attempted starts per hour with 5 minutes between attempts.
✓ ANS 3 attempted starts per hour with 5 minutes between each attempt.
Explanation. Honeywell A.P.Us recommend 3 continuous start attempts per hour. Boeing
757/767 notes add that a 60 minute cool-down period should be allowed before further start
attempts are made.
Q. 21. From where does the A.P.U receive a fire signal?.

It has its own system.
👉
It is dependent on the airframe system.
It is dependent on the engine fire system. ✓ ANS It has its own system.
Explanation. The A.P.U compartment has its own firewires sending a discrete signal to the
A.P.U fire controller.
Q. 22. What are the two most important signals when monitoring an A.P.U?.
👉
E.G.T and RPM.
👉
👉
👉
Oil Pressure and Inlet Pressure.
E.G.T and Oil Pressure. ✓ ANS E.G.T and RPM.
Explanation. E.G.T and RPM are monitored on the
A.P.U page of EICAS /ECAM systems.
Q. 23. One of the accessories driven from the A.P.U gearbox in a centrifugal switch, the
purpose of which is to.
arm the governed speed indication circuits and max. RPM governor.
cancel the ignition circuits and arm the overspeed protection circuits.
control starting and automatic extinguishing circuits.
✓ ANS 👉 cancel the ignition circuits and arm the overspeed protection circuits.
Explanation. NIL.
Q. 24. What iniates A.P.U shutdown?.

Fire detection, low oil pressure, high oil temperature.
Overspeed, fire detection, low oil quantity.
👉
Low oil pressure, low oil pressure, high oil temperature.
✓ ANS Fire detection, low oil pressure, high oil temperature.
Explanation. Honeywell 331-200 A.P.U handbook refers.
👉
C. On fault.
✓ ANS On engine start up.
Explanation. The E.E.C prepares for the changeover by resetting the E.E.C on shut down, but
does not actually do it until the next start. A simple single fault (compared to a complete channel
failure) will not cause a change over.
Q. 104. The possible combined output from all the scavenge pumps in a lubrication system will
be.
greater than the pressure pump output.
👉 greater than the pressure pump output.

less than the pressure pump output.
the same as the pressure pump output. ✓ ANS
Explanation. NIL.
Q. 105. If the knife-edge blade in a kinetic valve is fully in.
👉
pump pressure is constant.
👉
👉
servo pressure is being bled off.
👉
servo pressure is increasing.
✓ ANS servo pressure is being bled off.
Explanation. Rolls Royce The Jet Engine page 103 para 31 figure 10-8.
👉
👉
👉

MODULE 15 PART-4 Questions

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MODUEL15 PART-4

Module 15, GAS TURBINE ENGINE.

Q. 1. Engine anti-ice is taken from the.

inlet guide vanes.

Q. 4. Turbine case cooling utilizes.

Q. 5. Air for anti-icing is taken from the.

Q. 6. As air is bled off the engine, EGT will.

reducing fuel flow to reduce internal temperature.

Q. 10. Air bleed for an anti-ice system is.

Q. 11. With bleed valves open for anti-ice.

👉 thrust decreases, fuel consumption

Q. 1. In the H.E.I.U. the discharge resistors.

allows the capacitors to discharge when the unit is switched off.

Q. 2. In the H.E.I.U. the choke.

Q. 4. The advantage of an air starter system is.

it provides a more rapid start.

Q. 5. An advantage of a gas turbine starter is.

it provide high power for low weight.

Q. 7. For starting the engine, the H.P cock should be initially.

Q. 8. On light up, the gas temperature will.

Q. 9. Self sustaining RPM means that.

✓ ANS 👉 The engine will run independently of external help.

Q. 10. A 'hot start' with excessive temperatures may be caused by.

Q. 11. A dry motoring cycle would be required to.

clear the engine after a wet start.

👉 clear the engine after a wet start. Explanation.

Q. 13. Ignitor plugs are cleaned by.

light sand blasting.

Q. 14. An H.E.I.U works by.

Q. 15. When is ignition used?.

Q. 17. The spark in the High Energy igniter is supplied by.

Q. 18. Self sustaining speed is.

Q. 19. During normal running conditions.

👉 combustion is self supporting

Q. 21. In the H.E.I.U. the discharge resistors.

allow sufficient voltage to be stored to provide relight facilities up to 55,000 ft.

Explanation. Rolls Royce The Jet Engine page 129 refers

Q. 22. The rate of discharge of a H.E.I.U. is.

4 discharges per revolution.

👉 60 - 100 per minute. Explanation.

Q. 23. Why do turbine engine ignition systems require high energy?.

✓ ANS 👉 inspection of a magnetic chip detector. Explanation. Jeppesen A&P Technician

stator and rotor blades for FOD.

Radial inward flow turbine and axial-flow turbine.

Explanation. Jeppesen A&P Technician Propulsion Textbook 8-49.

WWW.DGCAQUESTIONPAPERS.IN - DGCA CAR -66 MODULE 15 PART 04

Q. 31. A clicking sound heard at engine coast-down in a pneumatic starter incorporating a

Q. 33. The purpose of an under current relay in a starter-generator system is to.

Magneto to engine timing is not critical.

do not require continuous operation. ✓ ANS 👉

✓ ANS 👉 A rise in the exhaust gas temperature. Explanation. NIL.

Q. 40. H.E.I.U ignitor plugs receive their electrical supply from.

Q. 41. An H.E.I.U is rated in.

Q. 42. A glow plug operates.

Q. 43. The resistor in a D.C. starter motor.

Explanation. Rolls Royce The Jet Engine page 122 refers.

✓ ANS 👉 no power supply is connected to the starter motor.

WWW.DGCAQUESTIONPAPERS.IN - DGCA CAR -66 MODULE 15 PART 04