Module 15 part 3

The density of air is very important when mixing fuel and air to obtain a correct fuel to air ratio. Which of the following weighs the most?. 75 parts of dry air and 25 parts of water vapor. 100 parts of dry air. 50 parts of dry air and 50 parts of water vapor.

A mixture ratio of 11:1 normally refers to. 1 part air to 11 parts fuel. a stoichiometric mixture. 1 part fuel to 11 parts air.

For what primary purpose is a turbine engine fuel control unit trimmed?. To obtain maximum thrust output when desired. To properly position the power levers. To adjust the idle RPM.

Under which of the following conditions will the trimming of a turbine engine be most accurate?. No wind and low moisture. High moisture and low wind. Jeppesen A&P Technician Propulsion Textbook 7-64. High wind and high moisture.

An H.M.U receives its signals from. E.C. ADC. thrust lever resolvers.

In order to stabilize cams, springs, and linkages within the fuel control, manufacturers generally recommend that all final turbine engine trim adjustments be made in the. decrease direction. increase direction. decrease direction after over-adjustment.

When trimming a turbine engine, the fuel control is adjusted to. set idle RPM and maximum speed or E.P.R. produce as much power as the engine is capable of producing. allow the engine to produce maximum RPM without regard to power output.

A supervisory electronic engine control (E.E.C) is a system that receives engine operating information and. controls engine operation according to ambient temperature, pressure, and humidity. adjusts a standard hydromechanical fuel control unit to obtain the most effective engine operation. develops the commands to various actuators to control engine parameters.

In a FADEC system, active control switchover occurs. when channels A and B are healthy. on shutdown. on engine start up only.

What causes the fuel divider valve to open in a turbine engine duplex fuel nozzle?. An electrically operated solenoid. Bleed air after the engine reaches idle RPM. Fuel pressure.

The valve on a vane type fuel flow measuring device becomes stuck. What safety backup is available for the engine fuel flow?. A differential pressure bypass valve. A bypass valve. A fuel bleed valve.

What are the principal advantages of the duplex fuel nozzle used in many turbine engines?. Allows a wider range of fuels and filters to be used. Restricts the amount of fuel flow to a level where more efficient and complete burning of the fuel is achieved. Provides better atomization and uniform flow pattern.

What is the purpose of the flow divider in a turbine engine duplex fuel nozzle?. Allows an alternate flow of fuel if the primary flow clogs or is restricted. Provides a flow path for bleed air which aids in the atomization of fuel. Creates the primary and secondary fuel supplies.

Which of the following turbine fuel filters has the greatest filtering action?. Stacked charcoal. Small wire mesh. Micron.

Where is the engine fuel shutoff valve usually located?. Aft of the firewall. Adjacent to the fuel pump. Downstream of the engine driven fuel pump.

Supervisory E.E.C sends its output to the. fuel valve. H.M.U/F.F.G. EGT thermocouple circuit.

If a FADEC loses its ADC input. In the short term it will. go to limit protection mode. go into hard reversion. go into soft reversion.

The primary purpose of an E.E.C is. to change analogue inputs into digital format to provide glass cockpit information and reduce flight crew workload. to save fuel, reduce crew workload and reduce maintenance costs. to change analogue inputs into digital format to reduce flight crew workload and provide maintenance information.

When both FADEC channels are healthy they will alternate. as selected on the flight deck. when one channel fails. on each engine start.

The purpose of the LP fuel pump is to. ensure the H.P fuel pump does not cavitate. pump fuel from the aircraft fuel tanks to the engine. ensure the fuel flow governor gets enough fuel.

In a FADEC system, what is the result of Channel A failing to receive information from a sensor?. Channel A will take the information from the backup sensor. Channel A will take the information from channel B. Channel B will assume control.

In a FADEC engine with a hydromechanical fuel system, how is fuel flow controlled?. By oil hydraulics. By fuel pressure. By electro-hydraulic servo valves (E.H.S.Vs).

On the approach. RPM should be above the minimum idle for maximum acceleration. RPM should be high. RPM should be lower than minimum for maximum acceleration.

The air data inputs to the FADEC E.C.U fails. The result will be: a lack of flight data. the E.C.U reverts to the fail-safe mode. uncorrected data from hard wired analogue sensors is utilised.

A FADEC system consists of. H.M.U, A.D.C and sensors. E.E.C, A.D.C and sensors. H.M.U, sensors and an E.E.C.

A fuel heater prevents. entrained water in fuel freezing. LP fuel filter icing. pipelines freezing.

When re-light is required in flight on a FADEC engine, the pilot selects. one igniter. igniter selected automatically. both igniters.

The position of fuel heater in fuel system is. between the fuel control unit and the burner manifold. after the LP fuel filter and before the H.P pump. before the LP fuel filter.

The E.E.C receives its primary power from. 115V AC emergency BUS. separate permanent magnet alternator. 115V AC main BUS.

The fuel trimmer on a turbo-prop engine isoperated. manually, to prevent high EGT due to altitude increase. automatically controlled in conjunction with FCU. manually to prevent excessive RPM at high altitude.

The main advantage of FADEC is. it has electrical control of hydro mechanical unit in all modes. efficiency is always maximum. it changes T.L.A to most efficient E.P.R rating.

Inlet side of a fuel pump has a. threaded micron filter. wire mesh filter. wire wound filter.

When a throttle is selected to increase power, the pressure drop across the Fuel Control Unit throttle orifice. increases then decreases due to decreasing pump output. drops then increases due to increasing pump output. remains the same.

When the E.E.C supervisory circuit senses a fault on the engine, the fault annunciator light will be on and the E.E.C will. remove fuel, down trimming signal only when E.E.C switch selected off. remove fuel, down trimming signal immediately. remove fuel, down trimming signal only after landing.

In-Flight the engine E.E.C controls. EGT. throttle position. fuel flow.

A FADEC does not have which of the following?. Control of thrust reverser operation. An automatic starting capability. Automatic control of engine fire bottles.

A FADEC consists of. Electronic controls, sensors and an H.M.U. Electronic control and throttle position transmitter. Electronic control only.

During aerobatic manoeuvres, what prevents fuel from spilling out of fuel tank vents?. Booster pump differential pressure. Baffle plates in tanks. Float operated valves.

After a bag tank replacement, where would you disconnect the system to carry out the flow checks?. At the engine. At tank outlet. Tank isolation cock.

What is the purpose of a silver strip on a fuel filter?. To detect excess metal. To detect sulphur in fuel.. To strain oil for contamination.

The basic concept of an H.P fuel control is. automatic adjustment of the fuel control unit by preventing excess fuel reaching the burners. the bleeding of excess fuel back to the input of the H.P pump swash plate piston. constant adjustment of the swash plate angle of the H.P fuel pump.

To prevent compressor surge and overheating of the combustion chamber due to over fuelling. a barometric unit is fitted. a throttle unit is fitted. an acceleration control unit is fitted.

When FADEC is in normal mode. channel A or B will be in command. channel A will be in command. channel B will be in command.

Out of the following thrust lever resolver angles, which one is the forward idle setting?. 5 degrees. 85 degrees. 40 degrees.

Trimming is a term applied to adjusting the. idle speed and maximum thrust. fuel specific gravity. part trim stop.

Fuel boost pumps are cooled using. ram air. Fuel pumps do not require cooling. fuel.

A fuel trimmer unit is adjusted at altitude. automatically, via a fuel trim unit. manually to compensate for propeller torque. manually to compensate for EGT change.

Baffles in a rigid fuel tank. help prevent micro-biological corrosion. strengthen the tank structure. prevent surge.

In a FADEC system, what does the E.E.C measure along with RPM ?. Pressure and Temperature. Pressure. Temperature.

In a FADEC system, how are the power supply windings for channel A and Channel B wound?. Two independent generators. On one generator with 2 separate windings. One generator and one winding.

If an Engine FADEC system loses air-data permanently, the pilot will. turn that E.E.C Off. select alternate pitot static. switch to Alt on the relevant E.E.C.

A FADEC system takes measurements from Engine Speed,. Temperature and Pressure. and Temperature. and Pressure.

Main purpose of the fuel boost pumps is to provide. emergency dump jettison. cross-feed fuel from one tank to another. fuel pressure to both engine pumps.

The swash plate in the fuel pump of an axial flow gas turbine engine is controlled by. servo hydraulic pressure. electrical servo control. servo fuel pressure.

The end fittings on a fuel non-return valve are normally of different sizes to. prevent incorrect installation. facilitate bleeding the system. allow a full fuel flow through the valve.

E.E.C receives signals from RPM sensor and. pressure sensors. pressure and temperature sensors. temperature sensors.

When does E.E.C channel change over occur?. On engine start up. On engine shut down. On fault.

The possible combined output from all the scavenge pumps in a lubrication system will be. greater than the pressure pump output. less than the pressure pump output. the same as the pressure pump output.

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.

Engine anti-ice is taken from the. LP compressor. HP compressor. turbine.

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.

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.

Turbine case cooling utilizes. LP compressor air. fan air. H.P compressor air.

Air for anti-icing is taken from the. accessory Gearbox. LP compressor. H.P compressor.

As air is bled off the engine, EGT will. remain constant. decrease. increase.

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.

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.

Inlet for cooling air for the first stage turbine blades is fed via the. blade root. grill holes. leading edge of the blade.

Air bleed for an anti-ice system is. tapped directly off the compressor. sent through a pressure regulator. sent through the air conditioning.

With bleed valves open for anti-ice. thrust is unaffected. thrust decreases, fuel consumption decreases. thrust decreases, fuel consumption increases.

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.

In the H.E.I.U. the choke. prolongs the life of the plug. protects the unit from excessive high voltages. prolongs the discharge.

In an electrical starting system, the slow start resistor is short circuited by the. centrifugal Switch. time switch. overspeed switch.

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.

An advantage of a gas turbine starter is: it provide high power for low weight. it does not require external connections. it uses a low volatile fuel.

If the engine fails to light-up, the starter cycle is canceled by. a centrifugal switch. a low pressure relay. a time switch.

For starting the engine, the H.P cock should be initially. in a position which depends on the fuel system. open. closed.

On light up, the gas temperature will. rise slowly. rise rapidly, then fall as RPM increases to idle. rise rapidly.

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.

A dry motoring cycle would be required to. clear the engine after a wet start. check engine run down time. check the operation of the igniters.

What type of turbine blade is most commonly used in air starter motors?. Reaction. Impulse. Impulse-reaction.

Ignitor plugs are cleaned by. compressed air and brushing lightly with soft brush. light sand blasting. steel wool.

An H.E.I.U works by. a discharging capacitor. ac busbar. a contact breaker.

When is ignition used?. For relight and start up. For continuous relight. At high altitudes.

The spark in the High Energy igniter is supplied by. a capacitor. a contact circuit breaker. the AC busbar.

Self sustaining speed is. V1 speed. the RPM at which the engine continues without external assistance. take off velocity.

During normal running conditions. combustion is intermittently supported by ignition. combustion is self supporting. combustion is continuously supported by ignition.

High energy ignition is required because of the. high flash point of the fuel. absorbed moisture content. low flash point of the fuel.

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.

The rate of discharge of a H.E.I.U. is. 4 discharges per revolution. 60 - 100 per second. 60 - 100 per minute.

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. To ignite the fuel under conditions of high altitude and low temperatures.

The type of ignition system used on most turbine aircraft engines is. low tension. capacitor discharge. high resistance.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

E.I.U ignitor plugs receive their electrical supply from. discharge inductor. starter system electrical circuit. discharge capacitor.

An H.E.I.U is rated in. Joules. Watts. Amps.

A glow plug operates. manually. by heat action. electrically.

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.

Where does the high voltage type turbine ignition receive its voltage pulse from?. Primary windings. Rectifier. Trigger transformer.

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.

The field of the D.C. starter motor used on gas turbine engine. series only. shunt or compound. series or compound.

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.

A glow plug may be used in place of a spark plug on. low temperature engines. large engines. small engines.

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.

When reconnecting a H.E.I.U , which cable must be reconnected first?. It makes no difference. T before H.T. T before L.T.

An aircraft flying through heavy rain may use, as a precaution. airframe deicing. engine intake deicing. continuous ignition.

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.

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.

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.

The compensation device on an E.G.T system must be re-calibrated after. each time a part of the system is replaced. does not need calibration. manufacture and overhaul.

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.

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.

What happens when bulb type thermometer resistive element goes open circuit?. Reads less than ambient. No reading given. Reads more than ambient.

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.

On an RPM system using a synchronous generator, the pointer is deflected by. a potentiometer. a Wheatstone bridge. an AC servomotor.

Torque pressure is usually read from a. torque meter. direct reading pressure gauge. tension gauge.

The drag cup in a tacho-generator is balanced by. calibrated hairspring. adjustable counterbalance weights. adjustment screw.

Fuel flow indication is taken from. after the H.P pump. after either H.P Pump or LP Pump. after the LP pump.

What power is required for E.G.T gauge indication?. No power - it is self generating. 115V AC. 28V DC.

A Bourdon tube instrument may be used to indicate. position and quantity. pressure and temperature. pressure, temperature, position and quantity.

Oil temperature thermocouples are usually constructed of. iron constantan. alumel constantan. chromel alumel.

The RPM indication of a synchronous AC motor tachometer is governed by the generator. current. frequency. voltage.

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.

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.

In what units are gas turbine engine tachometers calibrated?. Percent of engine pressure ratio. Percent of engine RPM. Actual engine RPM.

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.

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.

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.

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.

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. It is the most accurate instrument for establishing thrust settings under all conditions.

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.

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.

The indicator of a tachometer system is responsive to change in. voltage. frequency. current flow.

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.

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.

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.

Motor driven impeller and turbine fuel flow transmitters are designed to transmit data. using aircraft electrical system power. mechanically. by fuel pressure.

What unit in a tachometer system sends information to the indicator?. The two phase AC generator. The three phase AC generator. The synchronous motor.

Engine oil temperature gauges indicate the temperature of the oil. entering the oil cooler. entering the engine. in the oil storage tank.

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.

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.

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.

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.

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.

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.

Where is Turbine Outlet Temperature (T.O.T) measured?. Upstream of the turbine. Downstream of the turbine. In the combustion chamber.

A thermocouple indicator is basically a. milliammeter. millivoltmeter. milliohmeter.

A thermocouple indicator is connected to the. cold junction. hot junction. difference between the hot junction and the cold junction.

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.

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.

Modern oil pressure servo transmitters sense. absolute pressure. H.P oil pressure. differential pressure.

E.G.T thermocouples are usually made of. nickel and platinum. chromel and platinum. chromel and alumel.

Thrust in a high bypass engine is indicated by measuring. N3 RPM. neither of the above, thrust is not indicated in flight. fuel flow.

What power supply is required for a thermocouple system to work?. Alternating current. Direct current. Neither of the above.

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.

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.

Vibration pick-ups are located. on both fan and turbine cases. on the fan/compressor case. on the turbine case.

In a capacitive type fuel quantity indicating system the tank units are connected. series. parallel. series/parallel.

Torque measurement in a gas turbine engine is. not always reliable. highly reliable. required only when the turbine drives a propeller.

Vibration signals, when picked up,. go straight to indicator. go through half wave rectifier to indicator. the frequencies are filtered to exclude unwanted frequencies.

E.G.T is displayed in. Kelvin. degrees centigrade. degrees Fahrenheit.

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.

Engine vibration is monitored using. electromechanical devices. Fenwall type sensors. piezoelectric accelerometer.

Integrating fuel flow gives. average fuel flow. total fuel consumed. fuel flow and acceleration.

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.

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.

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.

When reheat is used, E.P.R. is reduced. remains constant. is increased.

When reheat is selected and in operation, the mass gas flow. decreases. remains the same. increases.

Screech liners in the afterburning jet pipe. prevent unstable combustion. prevent cyclic vibrations of large amplitude. acts as noise suppressors.

Water methanol for cooling is injected into the. compressor inlet or outlet. engine hot zone. combustion chamber.

On an injection system. methanol is injected neat. town water/methanol is injected. demineralized water/methanol is injected.

When using water methanol in an axial flow compressor, it is injected into the. compressor inlet or burner section. burner. intake.

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.

The primary purpose of water injection is to. decrease mass airflow. increase the calorific value of the fuel. cool the turbine.

Water used in a thrust augmentation system should be demineralised to prevent. blocking the jet. carbon formation. fouling the blades and vanes.

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.

Water methanol injection will increase thrust by up to. 70%. 50%. 30%.

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.

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.

Water/methanol is injected. at high temperatures. at high temperature, at high altitudes. at high temperatures or high altitudes.

The reheat ignition system which incorporates a platinum/rhodium element is known. catalytic ignition. hot-shot ignition system. spark ignition system.

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%.

Methanol is added to water when augmenting thrust in order to. increase the density of air entering the compressor. reclaim lost pressure at the compressor. reclaim lost heat at the turbines.

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.

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.

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.

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.

A free turbine is usually found on a. turbo-jet. turbo-fan. turbo prop.

A free turbine is. not directly connected to the power output shaft. connected directly to the propeller and compressor. connected directly to the power output shaft.

The fuel flow in a turboprop engine within the constant speed range is controlled. automatically. manually. No Control.

Torque measurement is taken from the. reduction gearbox. prop shaft. free turbine shaft.

Electrical propeller de-icing pads are. at the root. at the tip. on the trailing edge.

Fuel trimming on a turboprop engine is. pilot controlled. governor controlled. automatic.

What controls the fuel trimmer on a turboprop engine?. The blade angle. Propeller Control Unit. Engine Speed Governor.

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.

If an E.P.R gauge is installed on turbofans as a measure of power output, what is used on a turboprop?. gauge. Torque-meter. Thermocouples.

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.

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.

On a twin spool turbo-shaft engine, the free turbine is connected to the. output gearbox. H.P. gearbox. L.P. gearbox.

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.

An A.P.U has. automatically controlled thrust and is self contained. variable speed and is self contained. constant speed and is self contained.

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.

An A.P.U start cycle is completed at. 100% RPM. 75% RPM. 95% RPM.

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.

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.

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).

Fuel scheduling during A.P.U start and under varying pneumatic bleed and electrical loads is maintained. automatically by FADEC. manually through power control lever position. automatically by the A.P.U fuel control system.

An A.P.U is usually rotated during start by. a pneumatic starter. a turbine impingement system. an electric starter.

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.

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. .

In a large commercial passenger transport aircraft the A.P.U supplies. pneumatics and electrics. electrics. pneumatics.

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.

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.

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.

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.

When is the A.P.U at its greatest load?. With generator loads on line. With bleeds closed. With bleeds open and with generator loads on line.

Auxiliary power units provide. hydraulic and electrical power. pneumatic and electrical power. hydraulic and pneumatic power.

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.

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.

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.

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.

What initiates A.P.U shutdown?. Fire detection, low oil pressure, high oil temperature. Overspeed, fire detection, low oil quantity. Low oil pressure, high oil temperature.

Pipes, electrical cables and associated components of a fire-detection system should be. fire resistant. fire proof. fire retardant.

Acoustic linings made from composite materials are used in what section of the engine?. Not used to suppress noise. Hot section & Cold Section. Cold section only.

Vibration mounts are used for. stopping vibrations entering the engines. preventing engine vibration loads being transmitted to the airframe structure. damping out vibration stresses on engine when being transported on an engine stand.

An aircraft has a heavy landing and on inspection of the engine mounting bolts the bolts torque loading has reduced, you should. add washers to take up any gap or slackness and re-torque to correct value. remove bolt and carry out inspection as the bolt may have increased in length due to heavy landing. re-torque bolt up to correct torque value.

Forward engine mounts take which loads?. Thrust, vertical and shear loads. Centrifugal, thrust and axial. Thrust, vertical and impact.

Forward engine mounts take which form?. Castings. Forgings. Fabricated sheet steel.

Pipes around engines are. aluminium. mild seamless steel. stainless steel.

Fibrous metallic lining for noise suppression is used. for lobe type noise suppressors. in cold area. in hot area.

Noise lining in the fan area is made from. layers of bonded resin. porous type Honeycomb and backing sheet. felt with aluminium sheet.

A powerplant consists of. a basic engine plus E.C.U. a basic engine plus thrust reverser, exhaust system and gear box with accessories. the complete engine as it would be found on aircraft including all connections, controls, cowlings, intake etc.

Acoustic blankets are installed to. reduce noise levels. increase thermal efficiency. aid the streamlining of the engine.

When checking the effect of inertia on the engine after heavy landing you would first check the. thrust line. compressor shaft for distortion. module alignment.

Following the reports of a heavy landing you would. carry out a complete visual examination of the power plant. examine the engine mountings and borescope the nozzle guide vanes and turbine. examine the engine mountings and fuse pins.

The purpose of spring back and cushion on an engine power lever is. used when friction builds up in a system. used to prevent the controls hitting the fuel control stops. used when full travel is used but slight movement is still required on the fuel control unit.

What are sometimes installed in an engine mounting system to tune out the worst engine vibrations?. Spring cushioned mounting pads. Vibration absorbers of calibrated weight. Rubber encased wire-mesh vibration isolators.

Where are the lifting points on a high bypass turbine engine?. On the fan and compressor casing. On the fan, turbine and compressor casing. On the fan and turbine casing.

Rubber anti-vibration pads are fitted to engine. components to prevent fatigue. cradles to prevent damage during transportation. pylons to prevent vibration through the airframe.

Engine thrust is transmitted through mountings that. are designed to transmit eng thrust equally through front and rear supports. are designed to prevent the thrust line of the engine varying. allow for radial and axial expansion.

If you reduced the length of bellcrank (2) what would happen to the input to the C.U?. remain the same. reduce. increase.

A fire wire is installed. to withstand inertia, vibration, etc, encountered during normal operation. vertically. horizontally.