Module 15.10 Lubrication Systems Flashcards
What does the lubrication system do?
Distributes oil to the engine bearing compartments and the gearboxes.
What is a wet sump engine lubrication system?
A system that stores the oil supply in the engine.
What is a dry sump engine lubrication system?
A system that uses an external supply tank.
What are the two classifications of oil/lubrication systems?
Full-flow system
Constant pressure system
What is a full-flow lubrication system?
A system that has no way of regulating the oil pressure.
How does oil pressure change in the full-flow system?
It changes with changes in rotor speed (N2), oil temperature, and the flow areas downstream of the supply pump.
What is the supply pump driven by in a full-flow system?
The N2 rotor system via the gearbox.
What happens at higher N2 rotor speeds?
The supply pump produces a higher flow of oil (higher pressure).
What does higher oil temp do to the oil?
Lowers its viscosity.
What does low viscosity oil give?
Lower flow resistance and oil pressure.
A decrease in oil temp leads to what?
Higher oil pressure.
Where is the pressure relief valve installed in a full-flow system?
Between the delivery and the suction side of the supply pump.
What type of valve does a constant pressure system need?
A pressure regulating valve.
What does the pressure regulating valve in a constant pressure system do?
Holds the oil pressure to at the same value for all N2 rotor speeds.
In a constant pressure system, does oil temperature effect oil pressure?
No
Which lubrication/oil system is most commonly used?
Full-flow system.
What does the pressure relief valve do in a full-flow system?
Prevent oil pressure from becoming too high.
What is the main disadvantage of a full flow system?
A significant rise in oil temperature after a power reduction.
Name a critical lubrication point in the turbine?
Exhaust turbine bearing.
What can be used to cool the exhaust turbine bearing?
Air cooling and oil cooling.
Where is air cooling to the exhaust bearing turbine supplied from?
The early stages of the compressor.
What is the benefit of air cooling?
Reduces the amount of oil needed to provide cooling of the bearings.
What does lubricating oil for bearing cooling normally require?
An oil cooler.
What are the four lubrication subsystems?
Oil reservoir and supply system
Scavenge system
Vent system
Monitoring system
What two ways are used to fill the oil storage tank?
Gravity
Pressure
What is the filler on the storage tank surrounded by?
A scupper
What does the scupper on the storage tank do?
Catches any oil spilled during servicing and drains it to the engine drain mast.
Where is the strainer and check valve in the storage tank located?
Below the filler cap.
What does the check valve do?
Prevents the discharge of air and oil through the filler when the cap is not correctly fitted.
How can oil samples be taken from the tank?
Via a sampling tube in the strainer.
What is used to check oil quantity in the storage tank?
A sight glass.
Where does oil flow to from the tank?
Oil pump and pressure filter housing.
Where does oil flow to after the pressure oil filter?
Through the air oil heat exchanger and the fuel-cooled oil cooler.
What is the primary source of oil cooling?
Fuel-cooled oil cooler
How does a fuel-cooled oil cooler work?
The oil cools as it heats the fuel.
When the the air oil heat exchanger operate?
When additional oil cooling is required.
What two elements do oil pumps consist of?
Pressure supply element and scavenge elements.
What can be used as a bypass valve?
An oil cooler.
What do screens in the suction lines do?
Protect the oil pumps.
Where are screens in the supply line installed?
Upstream of the oil nozzles.
What do screens in the supply line do?
Protect the oil nozzles if the supply filter is bypassed.
Where can the oil cooler be located?
In the supply line downstream of the supply pump or in the scavenge line.
What is a hot tank oil cooler system?
The oil cooler is installed in the supply line. Oil from the bearing compartments is not cooled before it returns to the oil tank.
What is a cold tank oil cooler system?
The oil cooler is installed in the scavenge line the system. The oil from the bearing compartments is cooled before it returns to the oil tank.
What are the two main types of oil coolers?
Fuel-cooled
Air-cooled
What type of oil cooler do most large jet engine use?
Fuel-cooled oil coolers.
How many scavenge pumps does the oil pump and pressure filter housing have?
Seven
What do scavenge pumps do?
Removes oil and contaminants from the bearing compartments and gearboxes.
The scavenge oil returns to the engine oil tank through the scavenge oil filter.
Where is the breather in the vent system for lubrication located?
In the external gearbox.
What does the breather in the vent system for lubrication do?
Removes air from the scavenge oil.
What does the de-aerator do?
Separates the air from the incoming scavenge oil.
How long is higher pressure present for after engine shut down?
5 minutes
What two types of transmitter are used to monitor the oil?
Capacitance-type
Reed switch type
What happens to the float in a reed type transmitter if the oil level falls?
The float also falls.
What size particles do scavenge oil filters catch?
Parts more than 0.015 mm.
What is done to particles found in the system?
Removed and sent for analysis.
What process is used to find out about the internal wear of lubricated engine components.
Spectrometric Oil Analysis Program (SOAP).
What are megnet chip detectors?
Detectors that catches metal particles that are attracted to the magnet.
How can oil quantity be checked?
Sight gauges on the oil tanks or on the ECAM/EICAS displays in the flight deck.
Where is the oil tank located?
Above the gearbox.
What does the siphoning effect of the oil tank mean?
There is slow oil flow from the tank to the gearbox.
What does the anti-siphon device do?
Prevents slow oil flow from the tank to the gearbox due to the siphoning effect.
What should be observed when opening the filler cap?
The smell of the oil.
Where are details of the required oil type found?
On a label close to the oil tank filler cap.
Where is quantity of oil added stored?
The aircraft’s technical logbook.
What does pressure regulating system do?
Holds the pressure difference between the oil pressure and the vent pressure constant.
What are the two types of oil pumps?
Gear pump (most commonly used)
Gerotor pump
Where is the de-aerator installed?
At the inlet for the scavenge oil.
What size particles can the SOAP find?
Ranging from 0.001 and 0.02mm
