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 reciprocating engines?
To reduce friction between moving parts and remove heat
Name two important characteristics of aircraft engine oil
Free circulation and 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 filled between moving parts is easily broken which results in premature wear
What are some of the factors that must be considered by the engine manufacturer and 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?
Due to large operating clearances, high-pressure and temperature operations
Name some oil contaminants
Metal particles, dirt, carbon, moisture and acids
What is a possible indication of low oil pressure together with high oil temperature?
A low or inadequate oil level
In Ashless dispersant (AD) oils, what function does the dispersement perform?
Causes a 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 provide oil foaming, thermal expansion and air in the return oil
What can cause oil foaming?
Diluted oil, contaminated oil and oil level being too high
What controls oil pressure in a gear type oil pressure pump?
Relief valve
What function does the oil cooler bypass valve perform?
It directs oil either through the cooler or around it in order to maintain proper operating oil 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
