CH.2B The Powerplant and Related Systems Flashcards
THE FOUR-STROKE OPERATING CYCLE
Reciprocating airplane engines- continuous energy-creating process INTAKE COMPRESSION POWER EXHAUST
The continuous energycreating process in almost all reciprocating airplane engines is referred to as the four-stroke operating cycle - WHAT ARE THE STEPS?
INATKE of fuel/air mixture
COMPRESSION by teh piston
IGNITION and expansion of gases
VENTING of the burned gas
How is the engine speed for aircraft equipped with fix-pitch propeller displayed?
Tachometer in revolutions per minute (RPM)
What propeller is adjustable from cockpit?
Constant-speed propeller
What is the manifold pressure gauge used for?
Used in constant-speed propeller AC to monitor engine output by displaying the pressure inside the engine in inches of mercury (Hg)
What does the carburetor do?
Mixes incoming air with fuel and delivers it to the combustion chamer
What does the mixture control do?
Adjusts fuel/air mixture
What causes carburetor icing?
May be caused by fuel vaporization and decreasing air pressure in the venturi which causes a sharp temperature drop in the carburetor
When does carburetor ice occur?
When temperatures are below 21 degrees C ( 70F) and relative humididty is above 80%.
How do you combat effects of carb ice?
engines with float-type carburetors heat system which is designed to eliminate ice by routing air across a heat source before it enters the carburetor
What is the ignition system made up of
magnetors, spark plugs, interconnecting wires, and the ignition switch
When does detonation occur?
When the fuel in the cylinders explodes instead of burning smoothly
When does preignition occur?
Preignition is a result of fuel/air mixture being ignited in advance of the normal timed ignition
What is the main difference between fuel-pump and gravity-feed systems?
gravity systems do not include engine-driven or electric boost pumps or fuel pressure gauges
Why is it a good practice to refuel tanks following the last flight of the day?
to help prevent moisture buildup
What is a wet-sump system?
It uses an oil pump to draw oil from the sump and route it to the engine. Oil system operation can be monitored by referring to the oil pressure and temperature gauges
How does the AC cool the engine?
Cooling air enters the engine compartment through an inlet behind the propeller hub where it is further directed to the hottest part of the engine by baffles
How does the exhaust escape and how is it used?
Exhaust is normally directed out below the engine compartment through a muffler and tailpipe. Metal shrouds around the muffler capture heat which is used to defrost the windscreen and heat the cabin
What does a constant-speed propeller control permit?
A constant-speed propeller permits you to select a blade angle, appropriate for flight. Propeller control regulates engine RPM as shown on tachometer, while the throttle controls engine power output, as indicated on the manifold pressure gauge
What should you avoid with a constant-speed propeller
with a constant speed propeller you should avoid low RPM settings with high manifold pressure
What do alternators produce?
Alternators produce alternating current (AC) first, and then convert it to direct current (DC) for use in the airplane electrical system
As an airplane climbs, do you enrichen or lean the mixture to maintain an optimum fuel/air ratio?
LEAN the mixture
What is your first indication of carburetor ice in an airplane equipped with a fixed -pitch propeller ?
Your first indication of carburetor icing in an airplane with a fixed-pitch propeller will be a decrease in engine RPM
Explain why an engine equipped with a fuel injection system is less susceptible to induction icing than one equipped with a float-type carburetor
Sharp temp drop in a float-type carburetor due to fuel vaporization and decreasing air pressure in the venturi
If water vapor in the air condenses when the carburetor temp is at or below freezing, ice may form. Since engines equipped with a fuel injection system eliminate the carburetor, they are relatively free from the formation of induction icing.
The uncontrolled, explosive ignition of the fuel/air mixture within the cylinder’s combustion chamber describes which type of abnormal combustion? What actions can you take while airborne to help correct for this problem?
DETONATION.
Detonation can occur when the engine overheats. If you suspect detonation while in flight you should attempt to lower the cylinder temp by:
Retarding the throttle
Enriching the fuel mixture
AND/OR
Lowering the nose to increase airspeed and the cooling airflow around the engine
If the fuel grade specified for your airplane is not available, ca you use a lower/higher grade of fuel?
Sub with next higher grade, but only if approved by manufacturer.
Do not use lower fuel grade - can cause cylinder head and engine temp to exceed normal operating limits.
Describe functions performed by the engine oil system
lubricating the engine’s moving parts
cooling the engine by reducing friction and removing some of the heat from the cylinders
providing a seal btwn the cylinder walls and pistons
carrying away contaminants which are removed as the oil passes through a filter
If a constant-speed propeller is set to a high RPM with a blade pitch be high or low?
low
Immediately after engine start you notice that the ammeter shows a discharge. Is this normal?
NO
