PP Engine Cooling Systems

The primary purpose of baffles and deflectors installed around cylinders of air-cooled aircraft engines is to

create a low pressure area aft of the cylinders.
force cooling air into close contact with all parts of the cylinders.
increase the volume of air used to cool the engine.

What is the purpose of an augmenter used in some reciprocating engine exhaust systems?

To reduce exhaust back pressure.
To aid in cooling the engine.
To assist in displacing the exhaust gases.

Aircraft reciprocating engine cylinder baffles and deflectors should be repaired as required to prevent loss of

power.
fin area.
cooling.

Cracks in cooling fins that do not extend into the cylinder head

should be left alone and monitored.
may be repaired by removing the affected area and contour filing within limits.
may be repaired by adding a stiffener.

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?

AC 43.13-1A.
Engine manufacturer’s service or overhaul manual.
Engine structure repair manual.

A bent cooling fin on an aluminum cylinder head should be

sawed off and filed smooth.
left alone if no crack has formed.
straightened out as much as possible without breaking.

Where are cooling fins usually located on air-cooled engines?

Exhaust side of the cylinder head, inside the pistons, and connecting rods.
Cylinder head, cylinder walls, and inside the piston.
Cylinder head, cylinder barrel, and inside the piston.

How do cowl flaps aid in cooling a horizontally opposed aircraft engine?

Recirculates air through the engine cylinders.
Directs air through the engine cylinders.
Controls the amount of air flowing around the cylinders.

The position of the cowl flaps during normal cruise flight conditions is

closed.
open.
netural.

Generally, a small crack just started in a cylinder baffle

requires repair by reinforcing, such as installation of a doubler over the area.
requires no action unless it grows or is branches into two cracks.
may be stop drilled.

Which of the following assists in removing heat from the metal walls and fins of an air-cooled cylinder assembly?

An intercooler system.
A baffle and cowl arrangement.
An engine induction system.

During ground operation of an engine, the cowl flaps should be in what position?

Fully closed.
Fully open.
Opened according to ambient conditions.

The component(s) in a turbine engine that operate(s) at the highest temperatures is/are the

first stage turbine nozzle guide vanes.
turbine disks.
exhaust cone.

During an operational check of an electrically powered aircraft engine cowl flap system, the motor fails to operate. Which of the following is the first to be checked?

Flap actuator motor circuit breaker.
Flap actuator control switch.
Flap actuator motor.

(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.

Regarding the above statements,

only 1 is true.
both 1 and 2 are true.
only 2 is true.

Which of the following defects would likely cause a hot spot on a reciprocating engine cylinder?

Too much cooling fin area broken off.
A cracked cylinder baffle.
Cowling air seal leakage.

What part of an air-cooled cylinder assembly has the greatest fin area per square inch?

Cylinder barrel.
Rear of the cylinder head.
Exhaust valve port.

Reciprocating engines used in helicopters are cooled by

the downdraft from the main rotor.
a fan mounted on the engine.
blast tubes on either side of the engine mount.

The greatest portion of heat generated by combustion in a typical aircraft reciprocating engine is

converted into useful power.
carried out with the exhaust gases.
dissipated through the cylinder walls and heads.

A broken cooling fin on a cylinder head

is cause for rejection of the head.
may be filed to smooth contours if damage and/or repair limits are not exceeded.
should be left alone.

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

low RPM with oil dilution system activated.
idle RPM.
high RPM with mixture control in RICH position.

Cylinder head temperatures are measured by means of an indicator and a

resistance bulb sensing device.
wheatstone bridge sensing device.
thermocouple sensing device.

High cylinder head temperatures are likely to result from

a very lean mixture at high power settings.
fouled spark plugs.
a very rich mixture at high power settings.

The purpose of an intercooler when used with a turbocharger is to cool the

exhaust gases before they come in contact with the turbo drive.
turbocharger bearings.
air entering the carburetor from the turbocharger.

Prolonged idling of an engine will usually result in

excessive cylinder head temperatures.
increased oil consumption.
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

machining fins directly on the outside of the barrel.
shrinking on a jacket or muff of aluminum cooling fins around a steel cylinder steel.
machining fins directly on the outside of the barrel and shrinking on a jacket or muff of aluminum cooling fins around a steel cylinder sleeve (on different areas of the barrel).

What is the function of a blast tube as found on aircraft engines?

A means of cooling the engine by utilizing the propeller backwash.
A tube used to load a cartridge starter.
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.
Most is used to support combustion.
A small percentage is frequently bled off at this point to be used for air-conditioning and/or other pneumatic powered systems.

Which of the following results in a decrease in volumetric efficiency?

Cylinder head temperature too low.
Part-throttle operation.
Short intake pipes of large diameter.

The undersides of pistons are frequently finned. The principal reason is to

provide sludge chambers and sediment traps.
provide for greater heat transfer to the engine oil.
support ring grooves and piston pins.

What is the position of the cowl flaps during engine starting and warmup operations under normal conditions?

Full open at all times.
Full closed at all times.
Open for starting, closed for warmup.

Increased engine heat will cause volumetric efficiency to

remain the same.
decrease.
increase.

PP Engine Cooling Systems

Jon K

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