Lubrication

Question 1

What are the primary and secondary purposes of lubrication?

Answer 1

Reduce friction
&
Cooling

Question 2

How is oil grade determined?

Answer 2

-Operating loads
-Rotational speed of components
-Operating temperatures

Question 3

What are the 5 functions of lubrication?

Answer 3

Cools
Seals
Cushions
Cleans
Prevents corrosion

Question 4

What has the greatest effect on viscosity?

Answer 4

Temperature

Question 5

What is viscosity index?

Answer 5

States the rate of change in viscosity with a change in temperature
(Higher index rating = less effected by temp)

Question 6

Three reasons for the viscosity index?

Answer 6

1.Large engine operating clearances
2.High operating temperatures
3.High bearing pressures

Question 7

Aircraft oils are rated with a _______ number.

Answer 7

Saybolt
(Determined by the number of seconds it takes for 60 cc’s of material to drain through a calibrated orifice at a specific temperature)

Question 8

Multi-viscosity oils use ____ numbers.

Answer 8

SAE
(Converted from the Saybolt number)

Question 9

What are the 4 lubrication types?

Answer 9

Animal based
Vegetable based
Mineral based
Synthetic

Question 10

What are the most commonly used lubrication types in aviation?

Answer 10

Mineral
&
Synthetic (Semi-synthetic)

Question 11

Oils with the same Mil Spec may be interchanged as long as what?

Answer 11

They are the same grade

Question 12

What are the three states of lubricants?

Answer 12

Solid
Semisolid
Liquid (fluid)

Question 13

What is pour point?

Answer 13

Lowest temperature at which oil will pour without being disturbed

Question 14

What is cloud point?

Answer 14

Temp at which wax content begins to solidify and the oil becomes cloudy

Question 15

What is flash point?

Answer 15

When oil will flash but not burn

Question 16

What is fire point?

Answer 16

When oil is hot enough to continue to burn

Question 17

What oils may not be mixed?

Answer 17

Mineral based and synthetic

Question 18

Oil systems can be one of two types. What are they?

Answer 18

Dry sump or Wet sump

Question 19

What is the difference between Dry and Wet sump types?

Answer 19

Wet
-Oil supply is carried in the engine
-No scavenger pump

Dry
-Oil is carried in a tank separate from the engine
-Has scavenger pump

Question 20

What are the 3 methods of internal lubrication?

Answer 20

Pressure
Spray
Splash

Question 21

Oil tanks must be able to withstand how much pressure?

Answer 21

5 psi

Question 22

FAR 33.71 requires what?

Answer 22

On or around the filler opening must be marked with the word “OIL”

Question 23

An expansion space of ______ tank capacity or ______, whichever is greater, must be provided for oil tanks.

Answer 23

10%
1/2 Gallon

Question 24

What is a hopper tank used for?

Answer 24

Oil dilution and aids in quick warming of the oil

Question 25

What are 3 types of oil pumps?

Answer 25

Vane type Gear type Gerotor

Question 26

Oil pumps must have what in order to bypass extra oil?

Answer 26

Pressure relief valve

Question 27

What are the two types of oil filter systems?

Answer 27

Full Flow By-pass

Question 28

What are the differences between the Full-flow and By-pass type oil filter systems?

Answer 28

**Full-flow** -Filters all the oil at once -Has bypass valve to allow oil passage if filter becomes clogged -In Series **By-pass** -Filters the oil in portions -In parallel

Question 29

What are 3 types of filter constructions?

Answer 29

Screen type (reusable) Cuno (Discs and Spacers) Spin-on (Cartridge, Most common)

Question 30

What are oil coolers for?

Answer 30

Fluid to fluid heat exchanger Transfers heat from oil to air or fuel

Question 31

How do you determine oil temp in wet and dry sumps?

Answer 31

Sensing bulb