Engine Cooling Systems Flashcards
The primary purpose of baffles and deflectors installed around cylinders of air-cooled aircraft engines is to what?
force cooling air into close contact with all parts of the cylinders.
What is the purpose of an augmenter used in some reciprocating engine exhaust systems?
To aid in cooling the engine.
Aircraft reciprocating engine cylinder baffles and deflectors should be repaired as required to prevent loss of what?
cooling.
Which of the following should a mechanic consult to determine the maximum amount of cylinder cooling fin that could be removed when cracks are found?
Engine manufacturer’s service or overhaul manual.
Cracks in cooling fins that do not extend into the cylinder head…
may be repaired by removing the affected area and contour filing within limits.
A bent cooling fin on an aluminum cylinder head should be what?
left alone if no crack has formed.
Where are cooling fins usually located on air-cooled engines?
Cylinder head, cylinder barrel, and inside the piston.
How do cowl flaps aid in cooling a horizontally opposed aircraft engine?
Controls the amount of air flowing around the cylinders.
The position of the cowl flaps during normal cruise flight conditions is what?
closed.
Generally, a small crack just started in a cylinder baffle…
may be stop drilled.
Which of the following assists in removing heat from the metal walls and fins of an air-cooled cylinder assembly?
A baffle and cowl arrangement.
During ground operation of an engine, the cowl flaps should be in what position?
Fully open.
The component(s) in a turbine engine that operate(s) at the highest temperatures is/are the what?
first stage turbine nozzle guide vanes.
During an operational check of an electrically powered aircraft engine cowl flaps system, the motor fails to operate. Which of the following is the first to be checked?
Flap actuator motor circuit breaker.
(1) Some aircraft exhaust systems include an augmenter system to draw additional air over the engine for cooling.
(2) Augmenter systems are used to create a low pressure area at the lower rear of the aircraft engine cowling.
Both 1 and 2 are true.
Which of the following defects would likely cause a hot spot on a reciprocating engine cylinder?
Too much cooling fin area broken off.
What part of an air-cooled cylinder assembly has the greatest fin area per square inch?
Cylinder barrel.
Reciprocating engines used in helicopters are cooled by what?
a fan mounted on the engine.
The greatest portion of heat generated by combustion in a typical aircraft reciprocating engine is what?
carried out with the exhaust gases.
A broken cooling fin on a cylinder head…
may be filed to smooth contours if damage and/or repair limits are not exceeded.
An engine becomes overheated due to excessive taxiing or improper ground runup. Prior to shutdown, operation must continue until cylinders have cooled, by running engine at…
idle RPM.
Cylinder head temperatures are measured by means of an indicator and a what?
thermocouple sensing device.
High cylinder head temperatures are likely to result from what?
a very lean mixture at high power settings.
The purpose of an intercooler when used with a turbocharger is to cool the what?
air entering the carburetor from the turbocharger.
Prolonged idling of an engine will usually result in what?
Foreign material buildup on spark plugs.
The most common method and generally the best conduction of heat from the inside of a cylinder barrel to the cooling air is accomplished by what?
machining fins directly on the outside of the barrel.
What is the function of a blast tube as found on aircraft engines?
a device to cool an engine accessory.
Which statement is true regarding the air passing through the combustion section of a jet engine?
Most is used for engine cooling.
Which of the following results in a decrease in volumetric efficiency?
Part-throttle operation.
The undersides of pistons are frequently finned. The principle reason is to what?
provide for greater heat transfer to the engine oil.
What is the position of the cowl flaps during engine starting and warmup operations under normal conditions?
Full open at all times.
Increased engine heat will cause volumetric efficiency to what?
decrease.
