Reciprocating Engine Induction and Cooling Systems Flashcards
What does a fuel-injected engine have that prevents the loss of induction air if the air inlet filter should become covered with ice?
An alternating air valve allows warm air from inside the engine cowling to flow into the fuel metering system
What would be the effect on engine operation of an air leak in the intake pipe for one cylinder?
That cylinder would run lean and detonation could occur
What must be inspected on the cooling system of an air-cooled engine?
All of the baffles and air seals must be in place and in good condition
Why should an air-cooled engine not be run up to high power without the cowling installed?
The engine depends on the cowling to force air through the cylinder fins to remove the excess heat
Why do some air-cooled engine installations have cowl flaps?
Cowl flaps produce a low pressure on one side of the engine to pull air through the cooling fins on the cylinders
What document describes the proper use of cowl flaps on an air-cooled engine?
The pilot’s operating handbook
What is the relationship between the turbine engine upper temperature limits and power produced?
The higher the combustion temperatures that an engine can withstand without damage, the more power it is capable of producing.
What is the approximate percentage of air passing through a turbine engine that issued for cooling rather than combustion?
Approximately 75%.
What can be done to effectively allow higher gas temperatures in the turbine section of some engines?
Compressor bleed air and first stage rotor blades can lower temperatures enough to prevent heat damage
Compressor bleed air ducted through hollow sections in the turbine inlet guide vanes and first stage rotor blades can lower temperatures enough to prevent heat damage.
What effect does excessive heat have on reciprocating engines?
- It shortens the life of the engine parts
- Change the behavior of combustion
- Impairs lubrication
What is the purpose of cooling fins?
They remove heat from the cylinder heads
They provide a larger cooling surface area for removing heat from cylinder heads of air-cooled reciprocating engines.Airflow around the cooling fins transfers the heat from the cylinder heads to the air.
What are the reasons for using engine cowlings, baffles and cowl air seals?
The cowling performs two main functions: it streamlines the engine area to reduce drag, and is used together with the baffles and cowl air seals to direct airflow over the cylinders for cooling.
What is the purpose of cowl flaps and how are they operated?
They are used to control the amount of airflow through the cowling. They are either mechanically, electrically or hydraulically operated.
How does an augmenter cooling system work?
An outer tube placed over the exiting exhaust gas creates a venturi effect that draws more airflow over the engine, thus providing additional cooling.
Where should cowl flaps be positioned for ground operations?
Fully open.
What type of power is used to operate cowl flaps?
Manual, hydraulic, or electrical.
What should be done when cooling fin damage is discovered?
Repair according to the manufacturer’s overhaul and repair limitations or replace if too much of the cooling fin is broken off
Depending on the scope of damage, some cooling fins may be repaired subject to the manufacturer’s overhaul and repair limitations. If an excessive amount of the cooling fin is broken off, the cylinder should be replaced.
Why is cowl flaps adjustment important?
The movement must be within tolerances to keep cylinder head temperatures within allowable limits.
How are turbine engines cooled?
They are cooled by air passing through the engine. About 75% of the air passing through the engine is used for cooling which leaves only about 25% for combustion. This air is used to cool the combustion chamber and turbine.
In a turbine engine, where does the bleed air come from that is used to cool bearings and other parts?
The engine compressor.
Name the three components on the induction system of a reciprocating engine:
- Air scoop
- Carburetor or fuel control
- intake manifold
What could happen if the induction system becomes obstructed?
The engine may not be able to produce its rated power or it may not run at all. This may also be an indication of a dirty air inlet filter
How does induction icing affect engine performance?
It causes a reduction in power and possible erratic operation
How is induction icing categorized?
- Impact ice
- Fuel evaporation ice
- Throttle ice
What is the common method used to prevent induction system ice in a reciprocating engine?
Raise the temperature of induction air with a preheater
What causes fuel evaporation ice?
Because of the decrease in air temperature resulting from evaporation of the fuel after it is introduced into the air stream
Is carburetor throttle ice more likely to occur at a higher or lower power setting?
At a lower power setting because the throttle is partly closed, offering a larger surface area for ice accumulation
What may be the indication of leaking intake pipes?
The engine runs rough at low RPM
What happens to engine power when the carburetor heat is applied?
There is a noticeable drop in power
What could happen if carburetor heat is applied at high engine power settings?
Detonation
What are two types of supercharged induction systems?
- Internally driven
- Externally driven
How and at what point does an internally driven supercharger boost air pressure
An (engine-driven) impeller compresses the air/fuel mixture after it leaves the carburetor
What is used to power a turbocharger?
Engine exhaust gases directed onto the turbocharger turbine
What could result if the waste gate on a turbocharger system does not close fully
The engine may not be able to produce its rated power at certain altitudes, and the aircraft may not be capable of reaching critical altitude
What function does a turbocharger waste gate perform?
It controls the amount of exhaust gas either into or around the turbocharger, thus controlling the boot pressure of the turbocharger
What could cause a turbocharged engine to surge?
There could be a waste gate or controller malfunction
What are the most common ways to control a waste gate?
Either mechanically with linkages to the throttle or a separate control, or by an actuator that is driven by oil pressure
In a pressurized reciprocating aircraft, what component in the turbocharger system is used to limit the amount of turbocharger airflow used for cabin pressurization?
The sonic venturi
What is the function of a divergent-shaped jet engine inlet during subsonic flight?
Decrease air veloctiy and increase air pressure
It causes the air velocity to decrease with a subsequent increase in air pressure
What is the function of a divergent-shaped jet engine inlet during subsonic flight
It causes the air velocity to decrease with a subsequent increase in air pressure
Where are bellmouth inlet ducts typically found?
On helicopter engines
How do venturi-type particle separators, found on many turbine powered helicopters, function?
DELETE
A venturi is used to accelerate the flow of incoming air and debris through a curved intake. The debris gains too much inertia to allow it to follow the curved intake towards the engine, and is channeled away from the compressor
What are the most common methods used for anti-icing of turbine engine inlet ducts?
Engine bleed air and electric heating elements
