15.10 - Lubrication Systems

Question 1

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

Answer 1

It cools and pressurises the housing helping to reduce leakage

Question 2

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

Answer 2

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

Question 3

What is the purpose of individual scavenge pumps?

Answer 3

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

Question 4

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

Answer 4

Over-oils at low RPM

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

Question 5

What are the types of bearing lubrication applications?

Answer 5

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

Question 6

What is the advantage of squeeze film lubrication?

Answer 6

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

Question 7

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

Answer 7

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

Question 8

When should you service the oil tank?

Answer 8

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

Question 9

What are the three most common types of oil pump?

Answer 9

Vane
Gerotor
Gear type

Question 10

What is the gerotor made up of?

Answer 10

Gear teeth and idler gear

Question 11

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

Answer 11

Gear type pump.

Question 12

What are the four types of filter?

Answer 12

Cleanable screen
Fibre
Thread
Scavenge screen

Question 13

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

Answer 13

Fitted just before a bearing chamber

Question 14

What is the Delta-P indication for?

Answer 14

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

Question 15

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

Answer 15

Cooling the oil

Warming the fuel

Question 16

Where would you find an FCOC?

Answer 16

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

Question 17

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

Answer 17

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

Question 18

How is an AOHE valve activated?

Answer 18

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

Question 19

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

Answer 19

It prevents tank drainage on engine shutdown

Question 20

What are the three types of chip detectors?

Answer 20

Magnetic chip detectors
Indicating magnetic chip detectors
Pulsed chip detectors

Question 21

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

Answer 21

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

Question 22

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

Answer 22

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

Question 23

What would you see identifying a lubrication line?

Answer 23

The word “Lubrication” followed by sqares

Question 24

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

Answer 24

Oil through the heat exchanger

Question 25

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

Answer 25

A Gerotor pump

Question 26

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

Answer 26

It decreases

Question 27

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

Answer 27

A relief valve

Question 28

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

Answer 28

In-line thread filters

Question 29

How is sump pressure maintained?

Answer 29

By the breather system

Question 30

What would be the probable cause of high oil temperature?

Answer 30

A blocked pressure filter

Question 31

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

Answer 31

Before the consumers to maintain a constant pressure

Question 32

What is the purpose of the scavenge filters?

Answer 32

They protect the pressure pump

Question 33

What is the purpose of the pressure filters?

Answer 33

They protect the oil jets

Question 34

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

Answer 34

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

Question 35

Where would you find the oil pressure filter?

Answer 35

After the pressure pump, before the consumers

Question 36

A spur gear pump promotes ____ flow at ____ pressure.

Answer 36

A spur gear pump promotes LOW flow at HIGH pressure.

Question 37

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

Answer 37

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

Question 38

What is a fuel icing inhibitor used for?

Answer 38

It prevents the water in the fuel from freezing

Question 39

What are the two types of lubrication system?

Answer 39

Pressure relief valve system

Full flow system

Question 40

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

Answer 40

Protects the cooler to a overly high oil pressure