15.13 Start & Ignition (Level 1, 3 Questions)

Question 1

What are the two separate systems required for starting a gas turbine engine?
A) Fuel supply system and cooling system
B) Rotation of compressor/turbine and ignition of air/fuel mixture
C) Electrical power system and hydraulic system

Answer 1

B) Rotation of compressor/turbine and ignition of air/fuel mixture

Question 2

Which types of power sources can be used to start a gas turbine engine?
A) Only electrical power
B) Gas, air, hydraulic pressure, or electrical power
C) Fuel and water pressure

Answer 2

B) Gas, air, hydraulic pressure, or electrical power

Question 3

How are gas turbine engines started?
A) By rotating the high-pressure compressor
B) By igniting the fuel directly
C) By spinning the turbine blades with hydraulic power

Answer 3

A) By rotating the high-pressure compressor

Question 4

What is necessary to start a gas turbine engine?
A) Accelerate the compressor to provide sufficient air for combustion
B) Cool the combustion section before ignition
C) Decrease the compressor speed to stabilize airflow

Answer 4

A) Accelerate the compressor to provide sufficient air for combustion

Question 5

Why must the starter supply torque in excess of the torque required to overcome compressor inertia and friction?
A) To reduce fuel consumption during start
B) To ensure the compressor accelerates to self-sustaining speed
C) To cool down the compressor before ignition

Answer 5

B) To ensure the compressor accelerates to self-sustaining speed

Question 6

What must happen after ignition and fuel introduction during engine start?
A) The starter must be disengaged immediately
B) The starter must continue to assist the engine until self-sustaining speed is reached
C) The compressor must be slowed down to prevent overheating

Answer 6

B) The starter must continue to assist the engine until self-sustaining speed is reached

Question 7

Why must the starter continue to assist the engine considerably above the self-accelerating speed?
A) To prevent a delay in the starting cycle that could cause a hot or hung false start
B) To reduce fuel consumption during engine start
C) To cool the engine before ignition

Answer 7

A) To prevent a delay in the starting cycle that could cause a hot or hung false start

Question 8

What types of starters have mostly replaced earlier starting methods for gas turbine engines?
A) Hydraulic and manual starters
B) Electric and air turbine starters
C) Gas and mechanical starters

Answer 8

B) Electric and air turbine starters

Question 9

What is one advantage of cartridge starting in gas turbine engines?
A) It requires external power sources.
B) It provides a quick, independent method of starting.
C) It is the most fuel-efficient starting method.

Answer 9

B) It provides a quick, independent method of starting.

Question 10

Why is air starting commonly used on most commercial jet engines?
A) It is the heaviest and most complex system.
B) It is light, simple, and economical to operate.
C) It requires no external air supply.

Answer 10

B) It is light, simple, and economical to operate.

Question 11

How is the starter turbine in an air starter motor powered?
A) By electrical power from the battery
B) By air taken from an external ground supply, APU, or cross-feed from a running engine
C) By hydraulic pressure from the aircraft system

Answer 11

B) By air taken from an external ground supply, APU, or cross-feed from a running engine

Question 12

What are the two general types of electric starting systems used on gas turbine engine aircraft?
A) Hydraulic and pneumatic systems
B) Direct cranking and starter-generator systems
C) Air turbine and cartridge systems

Answer 12

B) Direct cranking and starter-generator systems

Question 13

What type of motor is typically used in a direct cranking electric starter for gas turbine engines?
A) Alternating current (A.C.) motor
B) Direct current (D.C.) motor
C) Hydraulic motor

Answer 13

B) Direct current (D.C.) motor

Question 14

On which type of engines are direct cranking electric starting systems mostly used?
A) Large turbofan engines
B) Small turbine engines like APUs and small turboshaft engines
C) Piston engines

Answer 14

B) Small turbine engines like APUs and small turboshaft engines

Question 15

How does a starter-generator system differ from a direct cranking electrical system in gas turbine engine aircraft?
A) It only functions as a starter and then shuts off
B) It functions as a starter and then operates as a generator once the engine is running
C) It uses hydraulic pressure instead of electrical power

Answer 15

B) It functions as a starter and then operates as a generator once the engine is running

Question 16

Why does a direct cranking starter require a disengagement mechanism after the engine starts, unlike a starter-generator?
A) Because it needs to prevent damage by disconnecting from the engine shaft
B) Because it continuously drives the engine shaft after starting
C) Because it is permanently engaged with the engine shaft

Answer 16

A) Because it needs to prevent damage by disconnecting from the engine shaft

Question 17

What is a key economic advantage of using a starter-generator unit in gas turbine engines?
A) It allows the engine to start without any electrical power
B) It combines the functions of starter and generator, reducing weight and parts
C) It eliminates the need for any maintenance on the starting system

Answer 17

B) It combines the functions of starter and generator, reducing weight and parts

Question 18

Why does the starter-generator include a compensating field among its internal windings?
A) To reduce sparking at the brushes and improve commutation
B) To increase the overall electrical resistance of the unit
C) To provide extra mechanical support to the starter-generator shaft

Answer 18

A) To reduce sparking at the brushes and improve commutation

Question 19

Why is a high peak current, such as 1500 amperes at 24 volts, typically required for starting a gas turbine engine with an electric starter?
A) To provide sufficient torque to overcome compressor inertia and friction loads
B) To ensure the starter motor operates at a lower speed
C) To reduce the overall electrical consumption during starting

Answer 19

A) To provide sufficient torque to overcome compressor inertia and friction loads

Question 20

What is the purpose of the motor relay closing when the battery and start switch are turned on during engine start?
A) To connect electrical power to the starter motor and begin cranking the engine
B) To activate the ignition system for fuel combustion
C) To disconnect the battery from the electrical system

Answer 20

A) To connect electrical power to the starter motor and begin cranking the engine

Question 21

Why is the igniter switched off after the fuel in the combustion chamber has been ignited?
A) Because the engine becomes self-sustaining and no longer needs external ignition
B) To save battery power during flight
C) To prevent damage to the igniter from prolonged use

Answer 21

A) Because the engine becomes self-sustaining and no longer needs external ignition

Question 22

Why is continuous ignition used during take-off, landing, or flying through volcanic clouds?
A) To keep the engine running by relighting the fuel if a flameout occurs
B) To increase engine power for better performance
C) To reduce fuel consumption during critical flight phases

Answer 22

A) To keep the engine running by relighting the fuel if a flameout occurs

Question 23

What power sources typically supply the capacitor discharge ignition system in a turbine engine?
A) Aircraft battery, 115 AC, and permanent magnet generator
B) Only aircraft battery and hydraulic power
C) Auxiliary power unit and fuel pump

Answer 23

A) Aircraft battery, 115 AC, and permanent magnet generator

Question 24

Why does a typical turbine engine ignition system have two exciter units and two igniter plugs?
A) To provide backup ignition for safety and reliability
B) To increase fuel efficiency during cruise
C) To reduce engine noise during startup

Answer 24

A) To provide backup ignition for safety and reliability

Question 25

What voltage is typically supplied to the input receptacle of a capacitor type turbine ignition system exciter unit? A) 115 volts AC B) 24 volts DC C) 12 volts DC

Answer 25

B) 24 volts DC

Question 26

What is 1 Joule per second equal to? A) 1 Newton B) 1 Watt C) 1 Pascal

Answer 26

B) 1 Watt

Question 27

Why is the capacitor-type ignition system only used during engine start in turbine engines? A) Because it is too heavy to operate continuously B) Because combustion continues on its own once initiated C) Because it cannot provide enough power for continuous operation

Answer 27

B) Because combustion continues on its own once initiated

Question 28

Why are exciters in turbine engines air-cooled? A) To increase spark intensity during engine start B) To prevent overheating during prolonged continuous ignition use C) To reduce electrical power consumption during normal operation

Answer 28

B) To prevent overheating during prolonged continuous ignition use

Question 29

How does the igniter plug of a turbine engine ignition system differ from a spark plug in a reciprocating engine? A) It produces continuous sparks only during engine start B) It is designed to operate under higher temperatures and pressures C) It uses fuel as the ignition source instead of electricity

Answer 29

B) It is designed to operate under higher temperatures and pressures

Question 30

Why must the electrode of a turbine engine igniter plug withstand much higher energy currents than a conventional spark plug? A) Because it operates continuously during normal engine operation B) Because it needs to produce a strong spark quickly despite causing some electrode erosion C) Because it runs on a lower voltage but higher frequency current

Answer 30

B) Because it needs to produce a strong spark quickly despite causing some electrode erosion

Question 31

Why is the electrode gap in a typical turbine engine igniter plug larger than that of a spark plug? A) Because operating pressures are lower, allowing the spark to arc more easily B) Because the igniter plug operates at higher voltages than a spark plug C) Because the larger gap reduces the risk of electrode erosion

Answer 31

A) Because operating pressures are lower, allowing the spark to arc more easily

Question 32

How does the constrained gap igniter plug operate at a cooler temperature compared to typical igniter plugs? A) By projecting further into the combustion chamber to stay cooler B) By not projecting into the combustion chamber liner and arcing beyond its face C) By using a smaller electrode gap to reduce heat generation

Answer 32

B) By not projecting into the combustion chamber liner and arcing beyond its face

Question 33

Why is it important to inspect the ceramic terminal of the ignition lead during ignition system maintenance? A) To ensure it has no arcing, carbon tracking, or cracks that could cause malfunction B) To verify the terminal is properly grounded to the engine frame C) To check that the terminal has sufficient electrical resistance

Answer 33

A) To ensure it has no arcing, carbon tracking, or cracks that could cause malfunction

Question 34

What is the correct procedure to safely remove ignition leads for inspection? A) Disconnect connectors first, then remove clamps and discharge any electrical charge by grounding the leads B) Remove clamps first, then disconnect connectors and discharge any electrical charge by grounding the leads C) Remove clamps, disconnect connectors, and immediately reinstall the leads without grounding

Answer 34

B) Remove clamps first, then disconnect connectors and discharge any electrical charge by grounding the leads

Question 35

What should be done before disconnecting the high-voltage ignition lead from the igniter plug? A) Remove the igniter plug first B) Disconnect the low-voltage primary lead from the ignition exciter and wait at least one minute C) Clean the igniter plug firing end with solvent

Answer 35

B) Disconnect the low-voltage primary lead from the ignition exciter and wait at least one minute

Question 36

When should an igniter plug be replaced? A) When the plug surface is granular, chipped, or damaged B) When the plug is clean and shiny C) Only when the igniter lead fails a continuity check

Answer 36

A) When the plug surface is granular, chipped, or damaged

Question 37

What is the correct procedure after installing igniter plugs in mounting pads? A) Leave them loose for adjustment later B) Tighten to the manufacturer's specified torque and safety wire the plugs C) Only hand-tighten the plugs without safety wiring

Answer 37

B) Tighten to the manufacturer's specified torque and safety wire the plugs

Question 38

How can the igniter function be tested during engine start? A) By measuring electrical resistance with a multimeter B) By listening for a clicking noise as the engine turns or looking for a visible spark during the start cycle C) By checking the oil pressure gauge

Answer 38

B) By listening for a clicking noise as the engine turns or looking for a visible spark during the start cycle

Question 39

Why is it dangerous to touch components of an activated turbine ignition system? A) Because the components are very hot B) Because the system uses very high voltages that can cause serious injury or death C) Because the components are heavy and can cause injury if dropped

Answer 39

B) Because the system uses very high voltages that can cause serious injury or death

Question 40

What should be done before starting any work on the starting system? A) Ensure the fuel supply is turned off B) Open and tag relevant circuit breaker switches to prevent operation C) Remove the engine cowling

Answer 40

B) Open and tag relevant circuit breaker switches to prevent operation

Question 41

Which safety precaution should be observed when carrying out tests on the starting system? A) Wear ear protection only B) Observe engine intake and exhaust hazard zones C) Disconnect the battery only

Answer 41

B) Observe engine intake and exhaust hazard zones

Question 42

What personal protective equipment (PPE) is recommended when handling hot parts during starting system maintenance? A) Safety goggles B) Correct hand gloves C) Ear plugs

Answer 42

B) Correct hand gloves

Question 43

What is the safest procedure before performing igniter maintenance? A) Disconnect the igniter lead coupling nuts at the exciter end first B) Remove the igniter plug before disconnecting any leads C) Touch the igniter to check for residual voltage

Answer 43

A) Disconnect the igniter lead coupling nuts at the exciter end first

Question 44

What type of tools should be used when handling igniter lead coupling nuts? A) Regular metal tools B) Insulated tools C) Plastic tools only

Answer 44

B) Insulated tools

Question 45

What is the most likely cause of accidental high voltage discharge during igniter maintenance? A) Dropping the igniter plug B) Touching the igniter with bare hands C) Using uninsulated tools on the coupling nuts

Answer 45

B) Touching the igniter with bare hands

Question 46

Why should ignition units not be touched for at least three minutes after opening the circuit breakers? A) To allow the engine to cool down B) To ensure all residual electricity has dissipated C) To prevent damage to the ignition units

Answer 46

B) To ensure all residual electricity has dissipated

Question 47

What is the consequence of touching ignition units without taking safety precautions? A) Minor electric shock B) Serious injury or death C) Damage to the engine starter system

Answer 47

B) Serious injury or death

Question 48

Before touching ignition units, what should always be followed? A) The pilot’s checklist B) The manufacturer's instructions and aircraft maintenance manual C) Engine operating procedures

Answer 48

B) The manufacturer's instructions and aircraft maintenance manual