Airplane Systems questions.

[Mohit_C]

Hi,

I have a few questions which I came across in the Volare Question Bank and I have a few doubts. Here are the questions:

Q102)
When leaning the mixture for the most economic cruise
fuel flow, excessive leaning will cause :
A) high engine rpm
B)low cylinder head and exhaust gas temperature (what I think)
C) high manifold pressure
D) high cylinder head and exhaust gas temperature (according to the mark scheme)

[If you lean for an economic cruise is when you have the ideal fuel/air ratio of 1/15 and with this you have the highest CHT and EGT. However if you lean excessively, it will reduce EGT and CHT again.]

Q525)
The speed of an asynchronous four-pole motor fed at a
frequency of 400 Hertz is:
A) 800 revolutions per minute.
B) 1600 revolutions per minute.
C) 12000 revolutions per minute. (according to the mark scheme)
D) 6000 revolutions per minute. (what I think)
[According to the formula: frequency (hz) = (Nš of poles * RPM) / 60 , gives 6000 RPM]

Q571)
If an engine fails to stop with the magneto switch in OFF
position, the cause may be :
A) defective condenser
B) fouled spark plugs
C) excessive carbon formation in cylinder head. (according to the mark scheme)
D) switch wire grounded (what I think)

Q583)
The conditions under which you obtain the highest
engine power are :
A) cold and humid air at high pressure. (what I think)
B) warm and dry air at high pressure.
C) cold and dry air at high pressure. (according to the mark scheme)
D) warm and humid air at low pressure.

[This question is ambiguous in the way that if it's referring to piston powered engines, the answer would be C) however for jet engines it would be A)]

Q393)
On a a normally aspirated engine (non turbo-charged),
the manifold pressure gauge always indicates...
A) a value equal to the QFE when the engine is at full power on
the ground. (what I think)
B) a lower value than atmospheric pressure when the engine is
running. (according to the mark scheme)
C) a greater value than atmospheric pressure when the engine
is running.
D) zero on the ground when the engine is stopped.

[If the engine is on full power (i.e. the butterfly valve is fully open) the admision pressure would be equal to the atmospheric pressure on a non turbo-charged engine]

Q389)
During climb with constant Manifold Air Pressure (MAP)
and RPM indication and constant mixture setting, the
power output of a piston engine :
A) stays constant.
B) increases. (according to the mark scheme)
C) decreases. (what I think)
D) only stays constant if the speed control lever is pushed
forward.

Q320)
The advantages of a chemical oxygen source for the
passenger cabin are :
1. reduced weight and volume,
2. easy storage and maintenance,
3. greater autonomy,
4. no risk of explosion,
5. reversible functioning,
6. no maintenance.
The combination regrouping all the correct statements
is:
A) 1, 2, 4, 6 (according to the mark scheme)
B) 1, 2, 3, 4, 5, 6
C) 2, 3, 5
D) 1, 3, 4, 5

[I personally don't know the answer to this but A) doesn't seem to be correct as point 2 and 6 contradict each other; one says easy storage and maintenance and the other says no maintenance]

Thanks.