Engine Lubrication

Question 1

A RECIPROCATING ENGINE IS FOUND TO HAVE EXCESSIVE OIL CONSUMPTION WITHOUT EVIDENCE OF ANY OIL LEAKS. WHAT IS THE LIKELY CAUSE?

Answer 1

The piston rings are worn or broken

Question 2

WHAT ARE THE FUNCTIONS OF LUBRICATING OIL IN RECIPROCATING ENGINES?

Answer 2

To reduce friction between moving parts and remove heat

Question 3

NAME TWO IMPORTANT CHARACTERISTICS OF AIRCRAFT ENGINE OIL

Answer 3

1) Light enough to circulate freely
2) Heavy enough to provide the proper film at operating temperatures

Question 4

WHAT COULD HAPPEN TO AN OIL THAT IS TOO LOW IN VISCOSITY AT NORMAL ENGINE OPERATING
TEMPERATURES

Answer 4

The oil film between moving parts is easily broken, resulting in premature wear

Question 5

WHAT ARE SOME OF THE FACTORS THAT MUST BE CONSIDERED BY AN ENGINE MANUFACTURER IN DETERMINING THE PROPER GRADE OIL FOR A PARTICULAR ENGINE

Answer 5

1) Operating load
2) Temperature
3) Rotational speed

Question 6

WHY DO AIRCRAFT RECIPROCATING ENGINE USE A RELATIVELY HIGH VISCOSITY OIL?

Answer 6

Large operating clearances
Operate at high temperatures & pressures

Question 7

NAME SOME OIL CONTAMINANTS

Answer 7

1) Metal particles
2) Dirt
3) Carbon
4) Moisture
5) Acids

Question 8

What is a possible indication of low oil pressure together with high oil temperature?

Answer 8

Low or inadequate oil supply

Question 9

IN ASHLESS DISPERSANT (AD) OILS, WHAT FUNCTION DOES THE DISPERSANT PERFORM

Answer 9

Causes sludge-forming materials to repel each other and suspend until they can be trapped by the oil filter or drained. Keeping the inside of the engine clean

Question 10

WHY DO OIL RESERVOIRS HAVE EXPANSION SPACE

Answer 10

To provide for:
1) Oil foaming
2) Thermal expansion
3) Air in the return oil

Question 11

WHAT COULD CAUSE OIL FOAMING?

Answer 11

1) Diluted oil
2) Contaminated oil
3) Oil level being too high

Question 12

WHAT CONTOLS OIL PRESSURE IN A GEAR-TYPE OIL PRESSURE PUMP?

Answer 12

The oil pressure relief valve

Question 13

WHAT FUNCTION DOES AN OIL COOLER BYPASS VALVE PERFORM?

Answer 13

Directs oil through or around the cooler to maintain proper oil temperature

Question 14

WHAT COULD BE A POSSIBLE INDICATION IF THE OIL COOLER PASSAGE BECOMES OBSTRUCTED?

Answer 14

High oil temperature

Question 15

WHERE IS THE OIL TEMPERATURE BULB USUALLY LOCATED?

Answer 15

The engine oil inlet

Question 16

WHAT DOES THE PRESENCE OF METAL PARTICLES IN AN ENGINE OIL FILTER INDICATE?

Answer 16

Depending on the type and size of the metal particles, this usually indicates abnormal wear/internal failure

Question 17

WHAT SHOULD BE DONE IF METAL PARTICLES ARE FOUND IN AN ENGINE OIL FILTER?

Answer 17

Follow engine manufacturer’s maintenance instruction

Question 18

WHERE IS THE MOST CRITICAL POINT OF LUBRICATION IN A GAS TURBINE ENGINE?

Answer 18

The turbine bearing

Question 19

WHAT TYPE OF OIL IS USED IN A TURBINE ENGINE OIL SYSTEM?

Answer 19

Synthetic oil

Question 20

WHERE ARE OIL SCREENS OR FILTERS MOST LIKELY LOCATED IN A TURBINE ENGINE OIL SYSTEM?

Answer 20

1) Oil pressure system
2) Scavenge system
3) Just before the oil jet

Question 21

NAME TWO TYPES OF TURBINE ENGINE OIL COOLERS

Answer 21

1) Air cooled
2) Fuel cooled

Question 22

WHAT COULD HAPPEN TO AN OIL THAT IS TOO LOW IN VISCOSITY AT NORMAL OPERATING TEMPERATURES

Answer 22

Become so thin the oil film between moving parts is easily broken resulting in premature wear.