Engine Lubrication Systems

Question 1

What is meant by the viscosity of engine lubricating oil?

Answer 1

The resistance of the oil to flow.

Question 2

What is meant by a wet sump lubrication system?

Answer 2

A lubrication system in which the oil is carried inside the engine itself.

Question 3

What is meant by a dry sump lubrication system?

Answer 3

A lubrication system in which the oil is carried in a tank that is not a part of the engine.

Question 4

How is oil temperature controlled in an aircraft reciprocating engine?

Answer 4

Hot oil is directed through the core of the oil cooler, but cold oil is directed around the outside of the core so it will not be further cooled.

Question 5

Is the oil temperature shown on the aircraft instrument panel the temperature of the oil entering the engine or of the oil leaving the engine?

Answer 5

It is the temperature of the oil entering the engine.

Question 6

What is the purpose of oil dilution in a reciprocating engine?

Answer 6

When very cold weather is anticipated, gasoline can be mixed with the lubricating oil before the engine is shut down. This reduces the viscosity of the oil and makes starting easier. When the engine is running, the gasoline evaporates out of the oil.

Question 7

What is the function of the hopper in the oil tanks used with some reciprocating engines?

Answer 7

Hoppers are a part of the oil dilution system. Only the oil in the hopper is diluted. This speeds up dilution and requires less gasoline.

Question 8

What happens to the gasoline that is used to dilute the oil in the crankcase of an aircraft reciprocating engine?

Answer 8

When the engine is running and the oil is warm, the gasoline evaporates out of it.

Question 9

What is the purpose of the sludge plugs in the crankshaft of a reciprocating engine?

Answer 9

They trap sludge that is in the oil and hold it until the engine is disassembled at overhaul.

Question 10

Which pump is the larger in a dry sump lubrication system, the pressure pump or the scavenger pump?

Answer 10

The scavenger pump has the greater volume.

Question 11

Why do follow-on filters have a spring-operated bypass valve in them?

Answer 11

In case the filter should plug up so it cannot pass any oil, the bypass valve will open and allow unfiltered oil to flow through the system.

Question 12

What is the function of a fuel/oil heat exchanger in the lubrication system of a turbojet engine?

Answer 12

This allows heat from the oil to warm the fuel so ice will not form on the fuel filters.

Question 13

What kind of oil is used in most turbojet engines?

Answer 13

Synthetic oil.

Question 14

Where are the last chance oil filters located in a turbojet engine?

Answer 14

They are located inside the engine just ahead of the nozzles that spray oil onto the bearings.

Question 15

Where is the oil tank in a dry sump reciprocating engine vented?

Answer 15

To the engine crankcase.

Question 16

What information must be displayed around the oil filler opening for a turbojet engine?

Answer 16

The word “Oil” and the permissible oil designations, or references to the AFM for permissible oil designations.

Question 17

What is the function of the oil control rings on the piston of an aircraft reciprocating engine?

Answer 17

They maintain the proper quantity of oil between the piston and the cylinder wall.

Question 18

What is meant by a spectrometric oil analysis?

Answer 18

It is a program in which a sample of oil is taken from the engine at regular intervals and sent to a labora-tory, where it is burned in an electric arc. The resulting light is analyzed for the wavelengths of the elements that are present in the oil sample. Traces of aluminum, copper, and iron in the oil indicate wear of the pistons or wrist pin plugs (aluminum), cylinder walls or piston rings (iron), main bearings or bushings (copper). A single sample is meaningless. There must be a series of samples taken at regular intervals to measure the change in the amounts of these metals.

Question 19

What indication would a pilot have if his oil supply was low?

Answer 19

The oil temperature would be high and the oil pressure would be low.

Question 20

What is meant by a hot-tank lubrication system?

Answer 20

A lubrication system in which the oil cooler is located in the pressure subsystem.

Question 21

What is meant by a cold-tank lubrication system?

Answer 21

A lubrication system in which the oil cooler is located in the scavenge subsystem. The oil that is returned to the tank has been cooled.