Lubrication Systems

Question 1

What is the primary purpose of an aircraft reciprocating engine lubricant?

Answer 1

To reduce friction between moving components/parts.

Question 1

What are two important characteristics relating to viscosity that an engine oil must possess?

Answer 1

It must be light enough to circulate freely and heavy enough to provide proper oil film at engine operating temperatures.

Question 1

What may happen to an oil that is too low in viscosity at engine operating temperatures?

Answer 1

It is likely to be come so thin that the oil film between moving parts is easily broken.

Question 1

What is the most critical lubrication point in a gas turbine engine?

Answer 1

The turbine engine bearing.

Question 1

Why is an oil tank required to have expansion space?

Answer 1

Oil expansion due to temperature change and air in the return oil.

Question 1

What factors must an engine manufacturer consider in determining the proper grade of oil for an engine?

Answer 1

Operating load, rotational speeds, and operating temperatures.

Question 1

Why must aircraft reciprocating engines use an oil with a relatively high viscosity?

Answer 1

Aircraft engines have large operating clearances, high operating temperatures, and high bearing pressures.

Question 1

Where does the oil temperature bulb usually sense oil temperature?

Answer 1

At the engine oil inlet

Question 1

What is the function of a dispersant additive as contained in ashless dispersant oil?

Answer 1

A dispersant helps keep the engine interior engine clean by keeping sludge forming contaminants in suspension in the oil until they can be trapped by the filter or drained out during an oil change.

Question 1

What is the purpose of an oil cooler bypass valve?

Answer 1

An oil cooler bypass valve directs oil through or around the oil cooler to keep the oil temperature within operating limits.

Question 1

What does the presence of metal particles in an engine oil filter indicate?

Answer 1

Possible engine internal failure.

Question 1

Name at least two areas of a turbine engine oil system where oil screens/ filters may be located.

Answer 1

1) Oil Pressure System
2) Scavenge system
3) At or just before the oil jets / Last chance filter

Question 1

What are some oil contaminants?

Answer 1

Acids, carbon, dirt, moisture, and metal particles.

Question 1

What type of oil is used in turbine engine oil systems?

Answer 1

Synthetic oil

Question 1

What could be the cause of excessive oil consumption without evidence of oil leaks in a reciprocating engine?

Answer 1

Worn or broken piston rings.

Question 1

What would be an indication of inadequate oil supply?

Answer 1

Low oil pressure and high oil temperature.

Question 1

What would be an indication of an obstruction in oil cooler passages?

Answer 1

High oil temperature

Question 1

What could cause oil foaming?

Answer 1

Diluted oil, contaminated oil, and the oil level being too high.

Question 1

What are two types of turbine engine oil coolers?

Answer 1

Air cooled and fuel cooled.

Question 3

What controls oil pressure in a gear type oil pressure pump?

Answer 3

An oil pressure relief valve.