Flashcards in PP PRT01 actual Deck (25)
a. compression ratio is independent of the octane rating.
b. the higher the octane rating is, the higher the possible compression ratio is Correct
c. the lower the octane rating is, the higher the possible compression ratio is
d. the higher the octane rating is, the lower the possible compression ratio is.
In a piston engine if the ratio of air to fuel, by weight, is
approximately 9:1, the mixture is said to be :
b. too weak to support combustion
In modern aircraft, a pilot can actuate the feather system
a. pulling the power levers backwards.
b. pulling the RPM lever backwards. Correct
c. pushing the RPM lever forward.
d. pushing the power lever forward.
The pitch angle of a propeller is the angle between the :
a. propeller reference chord line and the relative airflow.
b. propeller reference chord line and the extremity of the propeller.
c. propeller plane of rotation and the relative airflow.
d. reference chord line and the propeller plane of rotation. Correct
The compression ratio of a piston engine is the ratio of
a. weight of the air induced to its weight after compression.
b. volume of the cylinder with the piston at bottom dead centre to that with the piston at top dead centre. Correct
c. diameter of the bore to the piston stroke.
d. area of the piston to the cylinder volume.
Consider the variable-pitch propeller of a turbo-prop.
During deceleration :
a. when braking, the propeller supplies negative thrust and absorbs engine power. Correct
b. at zero power, the propeller thrust is zero and the engine power absorbed is nil.
c. when feathered, the propeller produces thrust and absorbs no engine power.
d. with propeller windmilling, the thrust is zero and the propeller supplies engine power.
The vapor lock is :
a. The abnormal mixture enrichment caused by a greater gasoline vaporisation in the carburettor.
b. A stoppage in a fuel feeding line caused by a fuel vapor bubble. Correct
c. The exhaust gases obstructions caused by an engine overheating.
d. The effect of the water vapor bubbles in the induction manifold caused by the condensation
Max Exhaust Gas Temperature is theoretically
associated with :
a. Mixture ratio very close to idle cut-out.
b. Mass ratio of 1/15. Correct
c. Cruising mixture setting.
d. Full rich setting.
Prolonged running at low rpm may have an adverse
effect on the efficiency of the:
a. A carburettor.
b. oil pump.
c. fuel filter.
d. sparking plugs
During a power change on an engine equipped with a
constant speed propeller, a wrong combination of
manifold pressure and RPM values results in excessive
pressures in the cylinders. This is the case when one
simultaneously selects a ...
a. low manifold pressure and low RPM.
b. high manifold pressure and low RPM. Correct
c. low manifold pressure and high RPM.
d. high manifold pressure and high RPM.
The crank assembly consists of
a. crankshaft, connecting rods and pistons. Correct
b. propeller, crankshaft, pistons and connecting rods.
c. Crankcase, crankshaft, connecting rods and pistons.
d. crankshaft, camshaft, valves, valve springs and push rods
An impulse magneto coupling
a. gives an automatic spark increase during high speed operation.
b. gives a retarded spark at starting Correct
c. reduces magneto speed during engine warm-up
d. advances ignition timing and gives a hotter spark at starting
For piston engines, mixture ratio is the ratio between the
a. volume of fuel and volume of air entering the carburettor.
b. mass of fuel and volume of air entering the carburettor.
c. mass of fuel and mass of air entering the cylinder. Correct
d. volume of fuel and volume of air entering the cylinder.
The working cycle of a four-stroke engine is :
a. induction, power, compression, exhaust.
b. compression induction, power, exhaust.
c. induction, compression, expansion, power.
d. induction, compression, power, exhaust.
One of the advantages of a turbosupercharger is that :
a. it uses the exhaust gas energy which normally is lost. Correct
b. it has a better propulsive efficiency.
c. there is no torsion at the crankshaft.
d. there is no danger of knocking.
Which of the following factors would be likely to
increase the possibility of detonation occurring within a
piston engine ?
a. using an engine with a low compression ratio
b. slightly retarding the ignition timing
c. using too lean a fuel/air mixture ratio Correct
d. the use of a fuel with a high octane rating as compared to the use of one with a low octane rating
The power of a piston engine decreases during climb
with a constant power lever setting, because of the
a. engine temperature.
d. air density.
Specific fuel consumption is defined as the :
a. quantity of fuel required to run the engine for one minute at maximum operating conditions.
b. maximum fuel consumption of the aircraft.
c. mass of fuel required to produce unit power for unit time. Correct
d. designed fuel consumption for a given rpm.
Which statement is true concerning the effect of the
application of carburettor heat?
a. it reduces the density of air entering the carburettor, thus leaning the fuel/air mixture
b. it reduces the volume of air entering the carburettor,thus enriching the fuel/air mixture
c. it reduces the density of air entering the carburettor, thus enriching the fuel/air mixture Correct
d. it reduces the volume of air entering the carburettor,thus leaning the fuel/air mixture
In a piston engine, the purpose of an altitude mixture
control is to :
a. weaken the mixture strength because of reduced exhaust back pressure at altitude.
b. enrich the mixture strength due to decreased air density at altitude.
c. correct for variations in the fuel/air ratio due to decreased air density at altitude. Correct
d. prevent a weak cut when the throttle is opened rapidly at altitude.
The maximum horsepower output which can be
obtained from an engine when it is operated at specified
rpm and manifold pressure conditions established as
safe for continuous operation is termed :
a. critical power.
b. rated power. Correct
c. maximum power.
d. take-off power.
To adjust the mixture ratio of a piston engine when
altitude increases, means to:
a. decrease the fuel flow in order to compensate for the decreasing air density. Correct
b. decrease the amount of fuel in the mixture in order to compensate for the increasing air density.
c. increase the amount of fuel in the mixture to compensate for the decreasing air pressure and density.
d. increase the mixture ratio.
A piston engine may use a fuel of a different grade than
a. provided that the grade is lower
c. provided that it is an aeronautical petrol
d. provided that the grade is higher
Fixed-pitch propellers are usually designed for
maximum efficiency at :
a. cruising speed Correct
c. full throttle