15.10 - Lubrication Systems Flashcards Preview

Module 15 - Gas Turbine Engines > 15.10 - Lubrication Systems > Flashcards

Flashcards in 15.10 - Lubrication Systems Deck (40)
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1
Q

What is the purpose of the air supplied to a bearing housing?

A

It cools and pressurises the housing helping to reduce leakage

2
Q

What are wet-sump and dry-sump lubrication systems?

A
Wet = stored in the engine itself
Dry = stored in an external container mounted to the engine
3
Q

What is the purpose of individual scavenge pumps?

A

The chip detectors can be used to determine if there’s any breakdown of the bearings and can be specified as to which one if so

4
Q

What are the two disadvantages of the pressure relief valve system?

A

Over-oils at low RPM

Slightly under-oils at max RPM when the valve kicks in

5
Q

What are the types of bearing lubrication applications?

A

Spray jet/pressure fed
Splash (gears in gearbox)
Metered
Film

6
Q

What is the advantage of squeeze film lubrication?

A

Minimises effect of radial loads and reduces vibration and damage from fatigue

7
Q

What is the purpose of the float valve in an engine oil tank?

A

Prevents a major oil leak if the cap of the oil tank is not fitted correctly

8
Q

When should you service the oil tank?

A

Not before 10 mins after shut down, and no longer than 1 hour after shutdown

9
Q

What are the three most common types of oil pump?

A

Vane
Gerotor
Gear type

10
Q

What is the gerotor made up of?

A

Gear teeth and idler gear

11
Q

What type of pump is usually seen on large gas turbine engines?

A

Gear type pump.

12
Q

What are the four types of filter?

A

Cleanable screen
Fibre
Thread
Scavenge screen

13
Q

Where would you find thread filters (last chance filters)?

A

Fitted just before a bearing chamber

14
Q

What is the Delta-P indication for?

A

For showing the filter is imminently going into bypass mode. Visible pop out or warning in the cockpit.

15
Q

What are the two reasons to use a fuel cooled oil cooler (FCOC)?

A

Cooling the oil

Warming the fuel

16
Q

Where would you find an FCOC?

A

Located in the fuel system, immediately before the LP fuel filter

17
Q

What is the purpose of the air/oil centrifugal breather?

A

Separates oil from the air mist in the gearbox. It vents it overboard and the oil is returned to the tank

18
Q

How is an AOHE valve activated?

A

By fuel pressure moving the modulating valve when the FCOC cannot maintain a certain temperature of the oil

19
Q

What is the purpose of the oil tank anti-syphon device?

A

It prevents tank drainage on engine shutdown

20
Q

What are the three types of chip detectors?

A

Magnetic chip detectors
Indicating magnetic chip detectors
Pulsed chip detectors

21
Q

What is the advantage of using the pulse chip detector system?

A

It can differentiate between large and small particles and can automatically send signals to the cockpit if deemed to be a serious malfunction

22
Q

What is the purpose of the HOPPER located in the oil supply tank of some dry sump engine installations?

A

It reduces the time required to warm the oil to operating temperatures

23
Q

What would you see identifying a lubrication line?

A

The word “Lubrication” followed by sqares

24
Q

An engine with a FOHE is controlled by a thermostatic valve that regulates the flow of what?

A

Oil through the heat exchanger

25
Q

What type of oil pump is usually used in an APU wet sump system?

A

A Gerotor pump

26
Q

What happens to the pressure drop across a throttle valve if it is opened?

A

It decreases

27
Q

What is used in an engine internal oil system to relieve excessive pump pressure?

A

A relief valve

28
Q

What type of filters are used in oil pressure spray jets as a “last chance filter”?

A

In-line thread filters

29
Q

How is sump pressure maintained?

A

By the breather system

30
Q

What would be the probable cause of high oil temperature?

A

A blocked pressure filter

31
Q

Where is the relief valve fitted in a pressure-relief valve system?

A

Before the consumers to maintain a constant pressure

32
Q

What is the purpose of the scavenge filters?

A

They protect the pressure pump

33
Q

What is the purpose of the pressure filters?

A

They protect the oil jets

34
Q

Which is higher in a FOHE; fuel pressure or oil pressure?

A

Oil pressure - so that if failure occurs in a FOHE, fuel will not enter the oil system

35
Q

Where would you find the oil pressure filter?

A

After the pressure pump, before the consumers

36
Q

A spur gear pump promotes ____ flow at ____ pressure.

A

A spur gear pump promotes LOW flow at HIGH pressure.

37
Q

How does a magnetic chip detector work when ferrous material sticks to the end?

A

The ferrous material bridges the gap between the detector centre (positive) electrode and the ground electrode.

38
Q

What is a fuel icing inhibitor used for?

A

It prevents the water in the fuel from freezing

39
Q

What are the two types of lubrication system?

A

Pressure relief valve system

Full flow system

40
Q

In a ACOC - what is the anti-surge (oil pressure relief) valve for?

A

Protects the cooler to a overly high oil pressure