Module 15.10 Lubrication systems Flashcards
Lubrication systems distribute oil to what?
- Bearing compartments
- Gearboxes
Where do wet sump engine lubrication systems store the oil?
In the engine
What do dry sumps use to store oil?
External supply tank
What are the two types of oil/lubrication systems?
- Full flow
- Constant pressure
The supply pump is driven by what rotor system?
N2 (High pressure turbine, which drives the accessory gearbox)
In full flow systems, oil pressure changes with what?
- N2 rotor speed
- Temperature
- Flow area
A leak in the oil system leads to what?
- Decrease in pressure
- Increase in the total flow area
On full flow, where would a pressure relief valve be installed between on the pump?
Between the delivery and the suction side
The constant pressure system is also called what?
Regulated pressure system
What valve type does a constant pressure system have?
Pressure regulating valve
What does the pressure regulating valve do?
Holds oil pressure at a given value at all N2 speeds from idle to full
Does oil temperature affect pressure in the constant pressure system?
No
Why is the full flow system most common?
- Simple
- No adjustments during maintenance
What are the two disadvantages of full flow?
- High oil pressure at idle
- Significant rise in oil temperature at power reduction
Why is the exhaust turbine bearing a critical lubrication point?
High temperature
What is used to cool oil?
Oil coolers
What are aluminium alloy oil tanks coated with to give fire resistance?
Silicon
What are the two refilling methods?
- Gravity
- Pressure
What prevents discharge of oil and air if the cap is not fitted properly?
Check valve\
Where does the scupper drain, drain oil to?
Engine drain mast
What is the purpose of the scupper drain?
To catch spilt oil
What is after the oil pump in the delivery system? and what is the safety feature?
Filter, with a pressure differential switch that operates a bypass valve
After the filter, where does the oil flow?
First to the air cooled oil cooler, then to the fuel cooled oil cooler
What are the filters after the heat exchangers called?
Last chance filters
What are the two most common types of oil pumps?
- Gear-type
- Gerotor-type
The gear type oil pump has what two elements?
- One for pressure oil
- One for scavenging
A gerotor pump’s scavenge capacity can be controlled by what?
Varying the size of the elements (this is a design thing)
The pressure regulating valve is located on what side of the pump?
Pressure side
When is the relief valve especially important?
When there are oil coolers in the system, as these can be easily ruptured
Where are the screens installed?
In the supply lines upstream of oil nozzles
If an oil cooler is in the supply line it is called what?
Hot tank system
If the cooler is in the scavenge lines, what is this system called?
Cold tank system
Why does the scavenge oil have air in it?
As it has been sprayed on too components
Where does scavenge oil return to?
Oil tank
What is the purpose of the breather?
System venting
\what separates air from the scavenge oil?
De-aerator
What does the oil indication subsystem monitor?
- Pressure
- Temperature
- Quantity
- Condition
What are the two types of transmitter used?
- Capacitance type
- reed switch type
How does a reed type transmitter work?
Movement of a float, gives a varying resistance
What can be said about the magnetic chip detectors?
Manually checked and some are electronically monitored
What happens to resistance when particles connect with the magnet on the magnetic chip detector?
Decreases
What is SOAP?
Spectrometric Oil Analysis Program
What can SOAP analysis find?
Particles in oil too small to be caught in filters
Oil quantity should be checked when?
Specified intervals (every time it lands)
On engines without anti-siphon it is important to check oil at how long after engine shutdown?
5-20 mins
After opening oil cap, if there is fuel smelt what does this indicate?
Leakage in fuel cooled oil cooler
