Lubrication system Flashcards
(21 cards)
A reciprocating engine is found to have excessive oil consumption without evidence of any oil leaks. What is the likely cause?
The piston rings are worn or broken
What are the functions of lubricating oil in reciprocating engines?
To reduce friction between moving parts and remove heat
Name two important characteristics of aircraft engine oil:
Free circulation
Proper oil fill at engine operating temperatures
What could happen to oil that is too low on viscosity at normal engine operating temperatures?
It may become so thin that the oil film between moving parts is easily broken, resulting in premature wear
What are some of the factors that must be considered by an engine manufacturer in determining the proper grade of oil for a particular engine?
The operating load and temperature as well as the rotational speed
Why do aircraft reciprocating engines use a relatively high viscosity oil?
They have large operating clearances and high-pressure and temperature operations
Name some oil contaminants
Metal particles
Dirt
Carbon
Moisture
Acids
What is a possible indication of low oil pressure together with high oil temperature?
Low or inadequate oil level
In ashless dispersant oils, what function does the dispersant perform?
It causes sludge forming materials to repel each other and remain in suspension until they can be trapped by the oil filter or drained. This keeps the oil passages and ring, grooves, free of harmful deposits and the inside of the engine clean.
Why do oil reservoirs have expansion space?
To allow for expansion of the oil after heat is absorbed from the bearings and gears, and after the oil foams as a result of circulating through the system
What could cause oil foaming?
Diluted oil
Contaminated oil
Oil level too high
What controls oil pressure in a gear type oil pressure pump?
A relief valve
What function does an oil cooler bypass valve perform?
It directs the oil through the cooler or around it to maintain proper oil operating temperatures
What could be a possible indication if the oil cooler passage becomes obstructed?
High oil temperature
Where is the oil temperature bulb usually located?
At the engine oil inlet
What does the presence of metal particles in an engine oil filter indicate?
Depends on the size and type of metal particles. It usually indicates abnormal wear and possible engine internal failure.
What should be done if metal particles are found in an engine oil filter?
Whatever the engine manufacturers maintenance instructions recommend
Where is the most critical point of lubrication in a gas turbine engine?
The turbine bearing
What type of oil is used in a turbine engine oil system?
Synthetic oil
Where are oil screens or filters most likely located in a turbine engine oil system?
The oil pressure scavenge system (main filters)
Just before the oil Jets (last chance filter)
Name two types of turbine engine oil coolers:
Air cooled and fuel cooled
