Lubrication Systems Flashcards
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 a reciprocating engine?
To reduce friction between moving parts and remove heat
Name two important characteristics of aircraft engine oil
The oil must be light enough to circulate freely yet heavy enough to provide the proper oil film at engine operating temperatures
What could happen to an oil that is too low in viscosity at normal engine operating temperatures?
It may become so thin that the oil film that is 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
Name some oil contaminants
Metal particles, dirt, carbon, moisture and acids
Why do aircraft reciprocating engines use relatively high viscosity oil?
Because they usually have large operating clearances and operate at high temperatures and pressures
What is a possible indication of low oil pressure together with high oil temperature?
A low or inadequate oil supply
In ashless dispersant ad oils, what function does the dispersant perform?
The dispersant 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 from harmful deposits and the inside of the engine clean
Why do oil reservoirs have expansion space?
To provide for oil foaming, thermal expansion and air in the returned oil
What could cause oil foaming?
Diluted oil, contaminated oil and the oil level being too high
What controls oil pressure in a gear type oil pressure pump?
An oil pressure relief valve
What function does an oil cooler bypass valve perform?
It directs the oil either through the cooler or around it in order to perform proper operating oil temperatures
What could be a possible indication if the oil cooler passage becomes obstructed?
A high oil temperature
Where is the oil temperature bulb usually located?
At the engine oil inlet
