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Module 15 > 15.13 Start And Ignition > Flashcards

15.13 Start And Ignition Flashcards

1
Q

Where is the engine turbine ignition system normally used?

A

Short period during the engine starter sequence and in the combustion chamber to ignite fuel

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2
Q

When would continuous ignition mode be used?

A

Uses at lower voltage and energy level, is used during certain flight conditions i.e if there is a possibility of an engine flame out, to relight the fuel and keep the engine from stopping

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3
Q

How do you start a GTE

A

Accelerate the high pressure compressor to provide sufficient airflow for combustion

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4
Q

Give some examples of when continuous ignition could be used?

A

Take off, landing and some abnormal or emergency situations, such as flying through a hailstorm or volcanic clouds

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5
Q

What are most turbine aircraft ignition system?

A

A high energy, capacitor-type ignition system and air cooled by a fan airflow

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6
Q

What is the order of starting a GTE

A

Ignition on, fuel, engine lights up, engine attains self-accelerating speed, ignition off, starter cuts out, engine reaches idle rpm

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7
Q

Why can working on a starter motor be dangerous ?

A

Starter motors generate high amounts of torque and are very heavy

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8
Q

What other ignition systems could turbine engines be equipped with?

A

Electronic type of ignition system

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9
Q

What can be left behind on the ignition exciter (igniter)?

A

High voltage and current, so it should not be touched if circuit breakers aren’t pulled or is the igniter lead is not connected

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10
Q

What tools should be used when disconnecting igniter leads?

A

Insulated tools and never bare hands

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11
Q

What should you always follow when or king on ignition systems ?

A

Manufacturer’s instructions and / or the AMM

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12
Q

What should be ensured before working on the ignition systems ?

A

There is no electricity left in the igniters

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13
Q

Should fuel be sprayed before ignition is on

A

No, ignition should be on before fuel

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14
Q

identical independent ignition units operating from a common low voltage (DC) electrical power source what are they?

A

Aircraft battery, 115 AC, permanent magnet generator

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15
Q

identical independent ignition units operating from a common low voltage (DC) electrical power source what are they?

A

Aircraft battery, 115 AC, permanent magnet generator

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16
Q

What is the generator turned by?

A

Directly by the engine through the accessory gearbox and produces power any time the engine is turning

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17
Q

Why is it imperative that the system can supply a high heat intensity spark?

A

Because they they often operate in low temp of high altitudes

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18
Q

What does a typical ignition system include?

A

Two exciter units two transformers, two intermediate ignition leads and two high tension leads. As a safety factor, the ignition system is a goal system designed to fire two igniter plugs

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19
Q

Before electrical energy reaches the exciter unit what does it pass through?

A

A filter that prevents noise voltage from being induced into the aircraft electrical system

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20
Q

What measures throttle position

A

Resolver (Boeing)
Potentiometer (Airbus)

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21
Q

From breaker points where do rapidly interrupted currents get delivered to?

A

Auto transformer

22
Q

What are advantages of cartridge starting

A

Quick independent engine start by using compressed gas

23
Q

What happens when the breaker closes and when it opens?

A

When closing the flow of current through the primary winding of the transformers establishes magnetic field. When breaker opens, flow of current stops and the collapse of the field induces a voltage in the secondary of the transformer

24
Q

What are disadvantages of cartridge

A

Single use so need replacing

25
Q

How is the cartridge ignited

A

By applying a voltage through the connector at the end of the breech handle

26
Q

1 joule per second = … watts?

A

1 watt

27
Q

All high voltage in the triggering circuits is completely what from the primary circuits?

A

Isolated

28
Q

How is the complete exciter sealed?

A

Hermetically

29
Q

What does hermetically seal also ensure?

A

Shielding against leakage of high-frequency voltage interfering with the radio reception of the aircraft

30
Q

What is the advantages of air starting

A

Lightweight and simple and economical

31
Q

What does an air starter transmit power through

A

Reduction gear and clutch

32
Q

Where does air from an air starter come from

A

External ground supply or APU or via a cross feed from the other engine

33
Q

What does the capacitor type system provide?

A

Ignition for turbine engines

34
Q

How is energy stored?

A

In capacitors

35
Q

What pressure air is used to start an engine

A

30-50psi

36
Q

How many capacitors are in each discharge unit?

A

Each discharge circuit incorporates two storage capacitors; both are in the exciter unit

37
Q

What pressure air is used to start an engine

A

30-50psi

38
Q

How many capacitors are in each discharge unit?

A

Each discharge circuit incorporates two storage capacitors; both are in the exciter unit

39
Q

What type of clutch is used in air starting

A

Sprag clutch

40
Q

What is an igniter plug?

A

Its electrode must be capable of withstanding a current of much higher energy than the electrode of a conventional spark plug. This high energy current can quickly cause electrode erosion, but the short periods of operation minimise this

41
Q

Explain a typical annular gap igniter plug?

A

sometimes referred to as a long-reach igniter because it projects slightly into the combustion chamber liner to produce a more effective spark

42
Q

What is a constrained gap plug?

A

It operates at a much cooler temperature because it does not project into the combustion chamber liner. This is possible because the spark does not remain close to the plug, but arcs beyond the face of the combustion chamber liner

43
Q

What is the typical maintenance of a turbine engine ignition system?

A

inspection, testing, troubleshooting, removal, and installation

44
Q

How long should you wait after shutdown of the capacitor?

A

20 mins

45
Q

What does the inspection of ignition systems consist of?

A

Ignition lead terminal inspection - ceramic terminal should be free of arcing, carbon tracking, and cracks.
The grommet seal should be free of flashover and carbon tracking.
The wire insulation should remain flexible with no evidence of arcing through the insulation.
Inspect the complete system for security of component mounting, shorts or high voltage arcing, and loose connections.

46
Q

How should you inspect ignition leads?

A

Remove clamps
Remove the safety locking wire and disconnect electrical connectors from exciter units and disconnect the lead from the igniter plug
Discharge any electrical charge
Clean leads
Inspect connectors
Inspect leads
Perform a continuity check of ignition leads
Reinstall leads, reversing the removal procedure

47
Q

What is the purpose of the magnetic drain plug on the transmission housing for

A

Removing any ferrous particles in the oil

48
Q

How do you inspect plugs?

A

Disconnect ignition leads
Remove igniter plugs
Inspect igniter plug gap
Inspect for fretting
Replace dirty or carbonised igniter plugs
Install igniter plugs in mounting pads
Check for proper clearance
Tighten igniter plugs to the manufacturer’s specified torque
Safety wire igniter plugs

49
Q

What are the two types of electrical starting

A
  • Direct cranking electrical system
    -Starter-generator systems
50
Q

What are the two types of electrical starting

A
  • Direct cranking electrical system
    -Starter-generator systems
51
Q

What current is used in a direct cranking electric starter

A

DC

52
Q

How long should be left before working on the igniters after pulling CB’s ?

A

At least three minutes

Module 15 (18 decks)

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