Oil And Cooling

Question 1

Purpose of oil system

Answer 1

Lubricates
Cleans
Cools
Seals
Cushions

Question 2

Oil cooler

Answer 2

Cools oil returning to the sump from the engine.

Question 3

Wet sump vs dry sump

Answer 3

Wet sump type
●Most GA reciprocating engines
●Archer (Lyc IO-360)
Oil supply carried in a sump or pan attached to the bottom of engine case.

●Dry sump type
●Radial, acrobatic, gas turbine engines
OIL CARRIED IN A SEPARATE TANK

Question 4

Oil temperature gauge

Answer 4

Measures effectiveness of the cooling system.
Avoid red line
In green arc before take-off
Min 180ºF required to boil water out of oil (212ºF required somewhere in engine)

Question 5

Oil pressure gauge

Answer 5

Measures the effectiveness of the oil pump
30 seconds in summer to respond after engine start
60 seconds in winter to respond after engine start
Oil Pressure Relief Valve
Below normal pressure may indicate a defective oil pump or low oil level
Above normal pressure may indicate a clogged oil line

Question 6

Type of oil

Answer 6

•Straight mineral oil (engine break-in)
•Ashless dispersant/detergent (normal operations)
•Synthetic (normal to extreme operations)
•Oil grade/viscosity
•Straight grade (SAE 50W)
•Multiweight (AEROSHELL 15W50)

Question 7

Purpose of cooling system

Answer 7

Reduce excessive heat
Decrease possibility of power loss, excessive oil consumption, and engine damage
Provided by air passing over fins on cylinders and through oil cooler

Question 8

Air cooled vs liquid cooled

Answer 8

Air cooled
Air passing over cylinder fins

Liquid cooled
Radiator/plumbing route fluid around cylinders
Not common on general aviation aircraft

Question 9

Thermal shock

Answer 9

•Occurs when engine parts that are operating at high temperatures (high power operations) are quickly cooled (idle power, high airspeed, cool or cold air)
•Air cooled & turbocharged engines are most susceptible
•Pilot must manage power, mixture, airspeed and cowl flaps with the engine’s welfare in mind, especially during training and descents

Question 10

Thermal distribution

Answer 10

Heat released by combustion
* 25%-30% is converted into useful power.
* 40%-45% is carried out with exhaust.
* 5%-10% is removed by oil.
* 15%-20% is removed by fins.

Question 11

Cowl flaps

Answer 11

Increases the cowling exit area to increase the amount of air circulating over cylinder fins
Controls engine cylinder cooling
●Open - high RPM & temperature operations (ground, TO, climb, go-around)
●Closed - lower RPM/temperatures (cruise, descent, landing)
When extended, they produce drag and sacrifice streamlining for added cooling
Aircraft specific
●Warrior, Arrow -No Cowl Flaps
●Seminole, Baron - Cowl Flaps