Final Test 3 Flashcards
The application of carburettor heat on an aircraft fitted with a CSU when ice is not present is accompanied by
[a] a drop in RPM followed by a slight increase in manifold pressure
[b] a drop in manifold pressure followed by a slight rise in manifold pressure at constant
RPM
[c] a drop in manifold pressure with no further change and constant RPM
[d] a drop in RPM with no further change
C
Hot air is less dense than cold air. Manifold pressure drops with the application of
carburettor heat, resulting in a power loss. However, the propeller governor moves the
blades towards a finer pitch setting thus preserving the RPM. Since there is no ice to
melt, this condition remains while ever the hot air is being inducted.
By the way, carburettor heat also produces a richer mixture. It has exactly the same effect
as a sudden increase in altitude.
To prevent excessive cooling of an engine during a long descent at a fixed throttle setting it is necessary to
[a] decrease indicated air speed and accept a reduced rate of descent
[b] increase indicated air speed and accept a reduced rate of descent
[c] decrease indicated air speed and increase rate of descent
[d] increase indicated air speed and increase rate of descent
A
Since the engine is aircooled, the rate of cooling will be decreased if the air flow is
decreased. This can be achieved by raising the nose and reducing the IAS. At a lower
IAS and the same power setting, the rate of descent would decrease [assuming the
descent was being conducted at a normal cruise descent speed in the first place].
If oil temperature is rising to near the red line during a long climb a remedy would be
[a] decrease power and indicated air speed
[b] increase power and indicated air speed
[c] decrease power and increase indicated air speed
[d] increase power and decrease indicated air speed
C
Since the heat is being produced by the combustion of fuel in the cylinders, a reduction
of power will cause less fuel to be burnt and decrease the amount of heat being
generated. An increase in IAS will provide more air flow and assist in dissipating the
heat.
A high cylinder head temperature during cruise could be due to
[a] manifold pressure too low for the selected RPM [b] mixture set too rich
[c] cowl flaps left open [d] detonation or pre-ignition
D
Detonation and pre-ignition both result in irregular combustion. In particular, the time
and place in the stroke where combustion is completed. Generally, most of the heat of
combustion is concentrated in the cylinder head where there is insufficient cooling fin
area to adequately dissipate the heat to the airstream.
Spark plug fouling would be most likely during
[a] long periods of ground operation at low power
[b] climbs at high power settings
[c] cruising flight in cold weather
[d] operation in conditions where carburettor ice is likely to form
A
One of the most common causes of plug fouling is oil deposits on the spark plug
electrodes. Engine oil contains a considerable amount on carbon, a by product of
combustion. Carbon is an excellent conductor of electricity and acts to short out the
plug. At low power there is insufficient heat to burn the oil that finds its way into the
combustion chamber.
The EGT setting that would produce the highest indicated air speed would be
[a] fully rich [b] peak exhaust gas temperature
[c] best power setting [d] best economy setting
C
More power produces more speed. When the mixture is set to best power, the TAS will be highest
for any given combination of manifold pressure and RPM. At any given cruising level, a higher
TAS means a higher IAS.
One consequence of operating an engine with excessively high oil temperature is
[a] Spark plug fowling [b] inadequate lubrication of some engine parts
[c] a very high oil pressure [d] sticking exhaust valves
B
The viscosity of oil reduces at high temperature [ie it becomes more “runny”]. If the oil’s
viscosity is too low, the protective film of oil breaks down permitting metal to metal
contact and rapid wear and engine damage. This is likely to occur when oil temperature is very
high.
Fuel vaporisation is most likely to occur during
[a] long periods of ground operation
[b] high engine temperatures and low ambient atmospheric pressure
[c] a long power off descent
[d] cruise with mixture leaned for best economy
B
At high power the high demand for fuel requires fuel to be pulled through the fuel lines
more quickly. This increases the likelihood of the fuel breaking down into vapour. If the
fuel is hot, the risk is further increased. Low ambient atmospheric pressure also contributes.
The purpose of a waste gate in a turbo supercharger is to
[a] regulate the speed of the turbine
[b] control the temperature of the exhaust gases
[c] prevent excessive pressure build up in the turbine
[d] control the fuel flow to the engine fuel pump
A
If the waste gate is closed, all of the exhaust gases pass through the turbine giving maximum
turbine [therefore compressor] RPM. As the waste gate opens, some of the exhaust gas can bypass
the turbine, so turbine RPM decreases. When the throttle is at low power or idle, all of the
exhaust gases by-pass the turbine and the engine behaves as a normally aspirated engine. As the
throttle lever is advanced, the waste gate remains fully opened until the throttle valve reaches the
end of its travel. Further advancement of the throttle lever then begins to close the waste gate
directing some of the exhaust gases through the turbine and further increasing manifold pressure.
If a leak develops before the waste gate in an engine fitted with a turbo supercharger
[a] fuel consumption would increase
[b] manifold pressure obtained at any given altitude and throttle position decreases
[c] manifold pressure obtained at any given altitude and throttle position increases
[d] less power is available due to increased exhaust back pressure
B
See the diagram for question No 9. If the exhaust gases are leaking out before the waste
gate, there will be a smaller mass of gas arriving at the waste gate. It follows that for a
given waste gate [therefore throttle] position, a smaller mass of gas will be directed
through the turbine thus reducing the compressor speed.
The correct setting for the pitch control during engine run-up of an engine fitted with a CSU is
[a] fully coarse during the magneto check [b] fully fine during the magneto check
[c] normal cruise position [d] set to hold 1700 RPM
B
In the fully fine position, the propeller is behaving as though it was a fixed pitched
propeller. This is desirable during engine run-up as it allows the pilot to easily check
engine power through variations in engine RPM.
During a descent at high speed and high power the propeller blades of a constant speed propeller will move
towards
[a] the fine pitch stops [b] the coarse pitch stops
[c] the centre of the pitch range [d] the position of minimum drag
B
With gravity to assist acceleration during a descent, the load on the propeller reduces.
If throttle position remains constant, the engine will tend to overspeed. The propeller
governor senses this tendency and moves the blades to the position that will remedy
overspeed ie towards coarse pitch.
A consequence of a low oil level in an engine is
[a] oil temperature and oil pressure will rise
[b] oil temperature and oil pressure will fall
[c] oil temperature will fall and oil pressure will rise
[d] oil temperature will rise and oil pressure will fall
D
One function of oil is to help cool the engine. If there is little oil in the sump, as that oil
collects the engine’s heat it becomes hotter than normal. Hot oil has less viscosity than
cold oil and provides less resistance to the oil pump. This eventually causes a drop in oil
pressure
A device that controls high current flow in an electrical system is
[a] a voltage regulator [b] a circuit breaker
[c] a condenser [d] a rectifier
If a centre zero ammeter shows a discharge during flight
[a] the system is operating normally [b] the battery is flat
[c] the master switch is off [d] the alternator has failed
