15.10 - Lubrication Systems Flashcards
What is the purpose of the air supplied to a bearing housing?
It cools and pressurises the housing helping to reduce leakage
What are wet-sump and dry-sump lubrication systems?
Wet = stored in the engine itself Dry = stored in an external container mounted to the engine
What is the purpose of individual scavenge pumps?
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
What are the two disadvantages of the pressure relief valve system?
Over-oils at low RPM
Slightly under-oils at max RPM when the valve kicks in
What are the types of bearing lubrication applications?
Spray jet/pressure fed
Splash (gears in gearbox)
Metered
Film
What is the advantage of squeeze film lubrication?
Minimises effect of radial loads and reduces vibration and damage from fatigue
What is the purpose of the float valve in an engine oil tank?
Prevents a major oil leak if the cap of the oil tank is not fitted correctly
When should you service the oil tank?
Not before 10 mins after shut down, and no longer than 1 hour after shutdown
What are the three most common types of oil pump?
Vane
Gerotor
Gear type
What is the gerotor made up of?
Gear teeth and idler gear
What type of pump is usually seen on large gas turbine engines?
Gear type pump.
What are the four types of filter?
Cleanable screen
Fibre
Thread
Scavenge screen
Where would you find thread filters (last chance filters)?
Fitted just before a bearing chamber
What is the Delta-P indication for?
For showing the filter is imminently going into bypass mode. Visible pop out or warning in the cockpit.
What are the two reasons to use a fuel cooled oil cooler (FCOC)?
Cooling the oil
Warming the fuel
Where would you find an FCOC?
Located in the fuel system, immediately before the LP fuel filter
What is the purpose of the air/oil centrifugal breather?
Separates oil from the air mist in the gearbox. It vents it overboard and the oil is returned to the tank
How is an AOHE valve activated?
By fuel pressure moving the modulating valve when the FCOC cannot maintain a certain temperature of the oil
What is the purpose of the oil tank anti-syphon device?
It prevents tank drainage on engine shutdown
What are the three types of chip detectors?
Magnetic chip detectors
Indicating magnetic chip detectors
Pulsed chip detectors
What is the advantage of using the pulse chip detector system?
It can differentiate between large and small particles and can automatically send signals to the cockpit if deemed to be a serious malfunction
What is the purpose of the HOPPER located in the oil supply tank of some dry sump engine installations?
It reduces the time required to warm the oil to operating temperatures
What would you see identifying a lubrication line?
The word “Lubrication” followed by sqares
An engine with a FOHE is controlled by a thermostatic valve that regulates the flow of what?
Oil through the heat exchanger
What type of oil pump is usually used in an APU wet sump system?
A Gerotor pump
What happens to the pressure drop across a throttle valve if it is opened?
It decreases
What is used in an engine internal oil system to relieve excessive pump pressure?
A relief valve
What type of filters are used in oil pressure spray jets as a “last chance filter”?
In-line thread filters
How is sump pressure maintained?
By the breather system
What would be the probable cause of high oil temperature?
A blocked pressure filter
Where is the relief valve fitted in a pressure-relief valve system?
Before the consumers to maintain a constant pressure
What is the purpose of the scavenge filters?
They protect the pressure pump
What is the purpose of the pressure filters?
They protect the oil jets
Which is higher in a FOHE; fuel pressure or oil pressure?
Oil pressure - so that if failure occurs in a FOHE, fuel will not enter the oil system
Where would you find the oil pressure filter?
After the pressure pump, before the consumers
A spur gear pump promotes ____ flow at ____ pressure.
A spur gear pump promotes LOW flow at HIGH pressure.
How does a magnetic chip detector work when ferrous material sticks to the end?
The ferrous material bridges the gap between the detector centre (positive) electrode and the ground electrode.
What is a fuel icing inhibitor used for?
It prevents the water in the fuel from freezing
What are the two types of lubrication system?
Pressure relief valve system
Full flow system
In a ACOC - what is the anti-surge (oil pressure relief) valve for?
Protects the cooler to a overly high oil pressure
