Cooling Systems

Question 1

What effect does excessive heat have on reciprocating engines?

Answer 1

Shortens life of engine parts, changes combustion behavior, impairs lubrication.

Question 2

What is the purpose of cooling fins?

Answer 2

Larger cooling surface for removing heat from cylinder heads, air flow around cooling fans transfers heat from cylinder heads into air.

Question 3

What are the reasons for using engine cowlings, baffles, and cowl air seals?

Answer 3

Streamlines engine area to reduce drag, used together with baffles and cowl air seals to direct airflow over cylinders for cooling.

Question 4

What is the purpose of cowl flaps and how are they operated?

Answer 4

Control airflow through cowling, either mechanically, electrically or hydraulically.

Question 5

How does an augmented cooling system work?

Answer 5

Outer tube placed over exhaust gas creates a venturi effect that draws more airflow over the engine thus providing additional cooling.

Question 6

Where should cowl flaps be positioned for ground operations?

Answer 6

Fully open.

Question 7

What type of power is used to operate cowl flaps?

Answer 7

Manual, hydraulic or electrical.

Question 8

What should be done when cooling fin damage is discovered?

Answer 8

Cooling fins may be repaired subject to manufacturer’s overhaul and repair limitations; if excessive amount of fin is broken off, cylinder should be replaced.

Question 9

Why is cowl flap adjustment important?

Answer 9

Movement must be in tolerances to keep head temperatures within allowable limits.

Question 10

How are turbine engines cooled?

Answer 10

Cooled by air passing through the engine.

Question 11

In a turbine engine, where does bleed air come from that is used to cool bearings in other parts?

Answer 11

Engine compressor.

Question 12

What is the relationship between turbine engine upward temperature limits and power produced?

Answer 12

Higher combustion temperatures that engine can withstand without damage, the more power it is capable of producing.

Question 13

What is the approximate percentage of air passing through a turbine engine that is used for cooling rather than combustion?

Answer 13

Approximately 75 percent.

Question 14

What can be done to effectively allow higher gas temperatures in the turbine section of some engines?

Answer 14

Bleed air ducted through hollow sections in turbine inlet guide vanes and first stage rotor blades can lower temperatures enough to prevent heat damage.