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Module 15 Richard > 15.21 Engine Monitoring and Ground Operation > Flashcards

15.21 Engine Monitoring and Ground Operation Flashcards

1
Q

What must be done prior to positioning an aircraft?

A

The logbook must be checked incase there are outstanding entries that may prevent aircraft movement or engine start up

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2
Q

How far must objects be away from the front of the engine if performing a ground run?

A

Up to 10 metres (30 feet)

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3
Q

With the engine running, where are you allowed to approach the engine?

A

Through the access corridor (only at idle!)

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4
Q

What type of fire extinguisher must be present when performing an engine ground run?

A

CO2

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5
Q

If ground running (idle or pressure running) with open engine cowlings, what must also be present?

A

A fire tender depending on local rules

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6
Q

Before ground running, who must be informed?

A

Air Traffic Control

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7
Q

What is “trimming” of an engine?

A

A term applied at idle speed, can be completed on idle run or on the engine test bed.

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8
Q

What must be known to correctly trim the idle speed of an engine?

A
  • OAT

- barometric pressure/airfield altitude (QFE)

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9
Q

What is idle trim?

A

It is the lowest idle speed permitted by the manufacturer

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10
Q

How is idle trim adjusted to gain a higher idle RPM?

A

By turning the adjuster in the anti-clockwise direction on the FCU

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11
Q

In what direction do most manufacturers recommend final engine trim adjustments must be made?

A

The increase direction

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12
Q

When carrying out acceleration checks on aircraft engines, what must be used as the datum?

A

The oldest engine - ensuring all engines accelerate at the same rate

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13
Q

Before shutting down the engines, what must be done?

A

The electrical power should be transferred back to the GPU or APU allowing the engine to idle for approximately 3 minutes prior to closing the HP fuel cock

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14
Q

What are the three groups engine indications can be divided into?

A
  • performance monitoring
  • system monitoring
  • condition monitoring
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15
Q

What is the EGT indication used to determine?

A

It is to recognise and prevent the critical condition of overheat

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16
Q

How is EPR measured?

A

It it the ratio of the jet pipe pressure to the fan inlet pressure

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17
Q

What is N1?

A

It is the % in relation to 100% of the design speed

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18
Q

How is thrust indicated on a centrifugal flow compressor engine?

A

The comparison of the relationship between engine RPM and jet pipe temperature (JPT)

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19
Q

Why can’t axial flow bypass engines use engine RPM compared to Jet pipe temperature (JPT) as the indication?

A

There is no direct relationship with there in an axial flow engine

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20
Q

What indications do axial flow bypass engines use?

A

EPR and N1

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21
Q

What happens in a power assurance test?

A 
Engines are operated at three different thrust settings:
- 50% take-off thrust
- 75% take-off thrust
- 100% take-off thrust
These are then compared on tables
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22
Q

How is the thrust of a turboprop and turboshaft engine calculated?

A

The engine torque through the gearbox

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23
Q

What is engine torque of a turboprop and turboshaft engine directly proportional to?

A

Engine horsepower

24
Q

What instrument is used in a turboshaft or turboprop aircraft to show the engine torque?

A

A torque meter

25
Q

What two types of sensing units provide torque readings?

A
  • electronic unit (electrical signal (twist of shaft) > torque)
  • hydro-mechanical (oil pressure > torque)
26
Q

When is an engine only ever removed?

A
  • a change of time limited parts

- for the repair of damages

27
Q

How is the engine data recorded on a modern aircraft?

A

Aircraft Condition Monitoring System (ACMS)

28
Q

After the data is collected by the ACMS, what happens to it?

A

It is transmitted to the Data Management Unit (DMU). The reports can be printed out or sent via data-link.

29
Q

What ACMS reports are used by the DMU?

A
  • routine (fixed time intervals)
  • on request (requested by pilot)
  • advisory (when defined parameters are exceeded)
30
Q

What is the SOAP?

A

Spectrographic Oil Analysis Program
- used to detect particles smaller than can be seen with the naked eye

It measures the colour and intensity of particles when burned

31
Q

What are MCD for?

A

Magnetic chip detectors

- they monitor metal wear within the engine and attract ferrous metals in the oil

32
Q

What can a borescope inspection identify?

A

Damage such as cracks, burn marks, hotspots and missing protective coatings

33
Q

What must be done after a borescope inspection has taken place?

A

A duplicate inspection must be carried out and all access plugs must be refitted

34
Q

Why must gas turbine engines have vibration monitoring systems?

A

They have very low vibration levels so issues may go unnoticed

35
Q

What are used to monitor modern engine vibrations?

A

Piezoelectric accelerometers (measured in inches per second or millimetres per second)

36
Q

Where are the piezoelectric accelerometers usually located on the engine?

A
  • one on the fan or LP casing

- one on the turbine casing

37
Q

What is looked for on a basic visual walk around inspection of an engine?

A
  • oil, fuel or air leakages

- items that are loose, broken, chafed or otherwise damaged

38
Q

What do the CAA recognise as 3 primary maintenance processes?

A
  • Hard time
  • On Condition
  • Condition-Monitoring
39
Q

What is hard time?

A

A preventative process which involves removal or items for overhaul or replacement at specified intervals.
A failure of these components would affect airworthiness

40
Q

What is on-condition?

A

A preventative process which involves inspection/tests to ensure an item can remain in service

  • Scheduled Servicing (periodic checks)
  • Unscheduled Servicing (due to failure or malfunction)
41
Q

What is Condition Monitoring?

A

Not a preventative process, but gathers information on a continuous basis. This means you can implement corrective procedures

42
Q

What are the three main methods of Condition Monitoring?

A
  • Flight deck indicators
  • Ground indicators
  • In flight recorders (IFR)
43
Q

Why are engines running on the ground, subject to FOD?

A

They suffer from core depression that forms at the inlet, sucking in FOD as there is no ram compression at slow speeds

44
Q

Why is FOD more damaging to Titanium manufactured engines?

A
  • Can cause “hard rubs”
  • It ignites at lower temperatures than it melts
  • Low heat conductivity
45
Q

During a compressor FOD inspection, if possible, what must be present?

A

A safety man inside the cockpit

46
Q

What must be placed on the inlet when entering the engine?

A

A protective mat - to protect the acoustic panels

47
Q

What must happen if, when inspecting an engine, the damage depth of a blade exceeds half of the maximum blending depth?

A

It must be rejected

48
Q

What is important about blending depth of an engine blade?

A

It must be twice the damage depth

49
Q

What is the purpose of a compressor wash?

A

It increases the efficiency of the engine

50
Q

What is “hot corrosion”?

A

Contamination of sulphur deposits in the core engine due to burning fuel, which erodes the surface finish and aerodynamic shape of the blades

51
Q

What is a desalination wash?

A

The engine is motored on the starter or on idle

- it is done periodically to remove salt deposits

52
Q

What is a performance recovery wash?

A

This is performed the same as the destination wash, however is used when the contamination has reached a stage where the desalination wash isn’t sufficient

53
Q

What, has a better cleaning action than cold water?

A

Hot water

54
Q

What is the abrasive cleaning method?

A

A fine grit (coke) is sprayed into the eye of the engine whilst it is rotating

55
Q

Why, in low temperature conditions is methanol not used on titanium as anti-freeze?

A

It is severely damaging to titanium

Module 15 Richard (18 decks)

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