Hydraulics, Instruments, Fire, Autopilot

Question 1

Low pressure in a hydraulic accumulator would produce
[a] no difference in operation unless the pump failed
[b] slow operation of services
[c] an overload of the power pump
[d] failure of all systems to operate

Answer 1

B
If the pressure in the hydraulic accumulator is low, the pump must do more of the work. Services
take longer to operate.

Question 2

If air has leaked into the lines of a foot operated hydraulic brake system an indication to the pilot would be
[a] a spongy feel to the brake pedals
[b] a normal feel at first application of pressure followed by a slow leak down of the pedal
[c] no resistance as the break pedal is easily pushed to the floor
[d] grabbing of the brakes on application of light foot pressure

Answer 2

A
Air is compressible, bubbles of air in the hydraulic oil allow it to compress under pressure, giving
the pedal a spongy feel.

Question 3

If a leak occurs in the lines of a foot operated hydraulic brake system an indication to the pilot would be
[a] a spongy feel to the brake pedals
[b] a normal feel at first application of pressure followed by a slow leak down of the pedal
[c] no resistance as the break pedal is easily pushed to the floor
[d] grabbing of the brakes on application of light foot pressure

Answer 3

B
The pedal feels normal on first application of pressure, but as the fluid escapes through the leak,
the pedal continues to move under foot - leak-down.

Question 4

An oleo leg on an undercarriage assembly
[a] should be kept correctly inflated with oil and gas
[b] should be protected from any compression loads
[c] is operated by the aircraft’s hydraulic system
[d] is only ever used on the nose wheel assembly

Answer 4

A
The oleo requires both oil and gas to operate correctly. An appropriately qualified person should
service the oleo to ensure that both are at the correct level.

Question 5

Low gas pressure in a hydraulic accumulator would cause
[a] reduced availability of pressure in an emergency
[b] failure of all systems
[c] increased wear on the main power pump
[d] one way only operation of services

Answer 5

A
The hydraulic accumulator also acts as a stand-by source of hydraulic pressure to allow limited
operation of services during an emergency. In this regard, it is like a battery in an electrical system
which can take over for a limited period if the alternator fails.

Question 6

A shimmy damper is a device designed to eliminate
[a] shocks imposed by landing loads
[b] vibration in tail wheel aircraft
[c] shimmy in the main wheels during take off
[d] vibration in the nose wheel during ground operation

Answer 6

D
Nose wheel shimmy occurs during ground operation. The shimmy damper acts as a shock
absorber, dampening the vibrations which cause shimmy.

Question 7

Some tachometers display a red arc between certain RPM settings. This indicates
[a] where detonation is most likely
[b] these RPM values must not be used under any circumstances
[c] never operate the engine at RPM values above that arc
[d] avoid continuous operation at these RPM values

Answer 7

D
Some engines are subject to harmonic vibrations at certain RPM settings. There is no immediate
problem for short term operations at these RPM values, such as during approach. The operator
should not make a habit of operating continuously at these RPM settings to avoid additional
expense at engine overhauls.

Question 8

When decreasing power on a turbo charged engine fitted with a CSU it is good practice to
[a] decrease manifold pressure before RPM
[b] decrease RPM before manifold pressure
[c] decrease RPM and manifold pressure together
[d] decrease manifold pressure only at constant RPM

Answer 8

A
Avoid the combination of high manifold pressure and low RPM, to prevent overboosting.

Question 9

If a manifold pressure gauge shows a rapidly fluctuating reading
[a] the instrument is unserviceable
[b] detonation is occurring
[c] fuel vaporisation is occurring
[d] the engine is seriously overheating

Answer 9

A
Probably vibrations causing rapid opening and closing of a crack in the lead. Detonation will not
show up on the manifold pressure gauge as it occurs after the inlet valve closes so no backpressure
can act in the inlet manifold.

Question 10

The instrument which gives the most direct reading of an aircraft’s attitude is
[a] the turn and balance indicator
[b] the direction indicator
[c] the artificial horizon
[d] inertial lead vertical speed indicator

Answer 10

C
The artificial horizon indicates attitude directly by displaying the degree of pitch and roll against
the gyro-stabilized horizon bar

Question 11

If a direction indicator becomes toppled during flight the instrument will
[a] need to be reset but will remain serviceable
[b] be unserviceable for the rest of the flight
[c] automatically reset itself and remain serviceable
[d] remain fixed on one heading

Answer 11

A
The direction indicator has freedom of movement in yaw only. Extreme attitudes may cause the
azimuth card to spin, but it will be useable again as soon as it has been caged and reset.

Question 12

An altimeter measures the vertical displacement of the aircraft from
[a] mean sea level
[b] the 1013 hPa pressure level
[c] the pressure reference datum set on the subscale
[d] the highest ground below the aircraft

Answer 12

C
The altimeter has no way of assessing where sea-level is. It simply measures the difference between
the ambient pressure and the pressure set on the sub-scale.

Question 13

If the static source becomes blocked during flight the instrument which will read zero is
[a] the airspeed indicator
[b] the altimeter
[c] the suction gauge
[d] the vertical speed indicator

Answer 13

D
A blocked static source isolates the VSI from the environment outside the aircraft. The pressure
inside and outside the capsule equalize and the capsule takes up its rest position and remains there
whatever the aircraft does

Question 14

Selection of the alternate static source will cause errors in
[a] the altimeter
[b] the air speed indicator
[c] the vertical speed indicator
[d] [a] and [b] but not [c]

Answer 14

D
The VSI does not read the static pressure directly. It reacts to the rate of change of static pressure

Question 15

The lag in the reading of the vertical speed indicator is rectified by
[a] inertial lead
[b] the electric vacuum pump
[c] the alternate static source
[d] cabin pressurisation

Answer 15

A
Inertial lead overcomes the lag by moving the pointer initially in response to vertical accelerations

Question 16

In the southern hemisphere, the reading of the magnetic compass will be ahead of the aircraft’s actual heading
[a] when accelerating on east or west
[b] when turning onto north
[c] when turning onto east or west
[d] when turning onto south

Answer 16

B
The compass is ‘nippy on north’.

Question 17

In the southern hemisphere the pilot should undershoot the desired heading when turning onto
[a] north
[b] south
[c] east
[d] west

Answer 17

B
The pilot should OVERSHOOT NORTH - UNDERSHOOT SOUTH.

Question 18

An exhaust gas temperature gauge
[a] operates from the aircraft’s electrical system
[b] has its own battery power
[c] requires no external electrical power source
[d] operates only when the master switch is on

Answer 18

C
The EGT, like the CHT operates on the principle of the thermocouple. The junction of two
dissimilar metals produces an electric current when heated. The current is produced within the
conductors without any outside electrical source being necessary.

Question 19

One effect of a blocked static source on aircraft instruments would be
[a] the airspeed indicator over reading on descent
[b] the airspeed indicator under reading on descent
[c] the vertical speed indicator over reading on climb
[d] the altimeter returning to zero

Answer 19

A
The ASI does the most dangerous thing. It over reads on descent. The total pressure of the more
dense air from the lower level is being led into the capsule, but it is being measured against the
thinner air which was trapped inside the case at the height the blockage occurred. The capsule
expands more that it should.

Question 20

The property of gyroscopic precession is the basis of operation of the
[a] direction indicator
[b] turn and balance indicator
[c] artificial horizon
[d] vertical speed indicator

Answer 20

B
As the aircraft moves in yaw, the gyro responds by rolling.

Question 21

A cylinder head temperature gauge is usually connected to
[a] all cylinders to obtain an average reading
[b] the engine crank case
[c] one cylinder only
[d] the exiting exhaust gases

Answer 21

C
It is possible for one cylinder to be seriously over heating due to preignition, but if it is not the
cylinder the CHT is connected to, there will be no immediate indication.

Question 22

Which instruments would be affected by the selection of the alternate static source?
[a] the altimeter and the air speed indicator
[b] the vertical speed indicator and the altimeter
[c] the altimeter only
[d] the vertical speed indicator only

Answer 22

A
The VSI would read correctly on the alternate static source.

Question 23

A pilot notices an unchanging altimeter reading during a steady climb. The most likely cause would be -
[a] blocked pitot tube.
[b] blocked static source.
[c] failed vacuum pump.
[d] mis-set altimeter subscale.

Answer 23

B
The altimeter has nothing to do with the pitot tube - it is required only by the ASI. If the static source
becomes blocked the altimeter is isolated from the environment. It will ‘freeze’ at whatever level
the blockage occurred. It doesn’t matter whether the aircraft is in a climb, cruise or descent.

Question 24

If the static source is blocked, the instrument which will overread in a descent is -
[a] altimeter.
[b] airspeed indicator.
[c] vertical speed indicator.
[d] artificial horizon.

Answer 24

B
If a blockage of the static source occurs, the pressure within the instrument case will always remain
equal to the pressure at the level at which the blockage occurred. However during a descent, the
air entering the pitot is becoming more and more dense as the height decreases. The capsule
expands more than it should because the increasingly dense air is being measured against the lower
pressure trapped within the instrument case.

Question 25

Engine fire bottles are discharged
[a] into the exhaust system
[b] into the inlet manifold
[c] into the carburettor inlet
[d] inside the engine cowling area

Answer 25

D
The fire bottles are discharged into the engine cowling.

Question 26

When wire loop fire detection system test switch is depressed, what is being tested?
[a] The fire detectors fitted to the wire loop within the engine cowling
[b] The contents of the fire bottles
[c] The entire system including the fire detectors and the wire loop
[d] Only the continuity of the wire loop without the fire detectors

Answer 26

D
The test circuit runs around the loop and then to earth. I proves that the loop is intact but doesn’t
indicate the serviceability of any particular detector.

Question 27

The most common extinguishing agent used in High Rate Discharge extinguishing systems is
[a] Carbon Dioxide gas (CO2)
[b] Dry Chemical Powder
[c] Halon gas (Halogenated hydrocarbon agents)
[d] Metal Bromide gas

Answer 27

C
Halon [halogenated hydrocarbons] are used most commonly in aircraft fire extinguishing systems.

Question 28

High Rate Discharge fire extinguishing systems, discharge the extinguishing agent
[a] into the cabin on large pressurised aircraft
[b] into the intake turbine on jet aircraft
[c] into the carburettor intake on piston engine aircraft
[d] into the engine nacelle on piston engine aircraft

Answer 28

D
All extinguishing agents are discharged into the engine cowl [where the fire is].

Question 29

Wire loop fire detection systems are designed to detect fires
[a] in the exhaust section of a turbine
[b] in the inlet section of a turbine
[c] in the engine cowl enclosure
[d] in the cabin and airframe structure on large aircraft

Answer 29

C
The loop runs around the inside of the engine cowl.

Question 30

Ionizing and optical (photoelectric) smoke detectors are used to detect possible fires in
[a] the engine cowl area
[b] the engine air intake section
[c] the turbine outlet section
[d] the cabin or crew compartment

Answer 30

D
Smoke detectors are used to detect smoke [therefore the possibility of fire] in areas where smoke
can accumulate. They would be quite useless in an engine cowl where wind would simply carry
any smoke away.

Question 31

The most likely cause of a rapidly fluctuating cylinder head temperature gauge would be
[a] detonation
[b] pre ignition
[c] high oil temperature
[d] faulty gauge

Answer 31

D
A cylinder head is a large heavy piece of metal. There is no way that the temperature of a cylinder
head could suddenly change and cause fluctuating readings.

Question 32

In the Southern Hemisphere, the magnetic compass reading is behind the aircraft’s heading when turning through
[a] East
[b] West
[c] North
[d] South

Answer 32

D
The compass is ‘nippy on north - sluggish on south’. When turning onto south the compass lags
behind the aircraft’s actual heading during the turn.

Question 33

Fluctuating cylinder head temperature gauge readings are noticed during cruising flight. One possible cause is
[a] the ice is building up in the induction manifold
[b] that there is a faulty electrical connection in the instrument circuit
[c] that all of the engines cylinders are pre-igniting
[d] that the mixture is over rich

Answer 33

B
A cylinder head is a large heavy piece of metal. There is no way that the temperature of a cylinder
head could suddenly change and cause fluctuating readings.

Question 34

During descent after encountering icing, the ASI is found to under read by an increasing amount. This could
[a] be caused by an ice-blocked static vent
[b] be caused by both ice-blocked pitot and static tubes
[c] never be attributable to icing
[d] be caused by a partially ice-blocked pitot tube

Answer 34

D
The air entering the pitot transfers its pressure to the inside of the capsule in the ASI. A partial
blockage due to ice on the pitot would restrict the flow of air and cause the instrument to underread. This would be aggravated by the increasing static pressure during a descent which would
also act to limit the expansion of the capsule. Note that a blocked static source would cause the
instrument to overread on descent.

Question 35

During the climb out after take-off you note that the altimeter’s main scale reading remains unaltered. Which of
the following is the most likely cause
[a] fully blocked static vents and pitot tube
[b] fully blocked pitot tube
[c] partially blocked static vents
[d] fully blocked static vents

Answer 35

D
The altimeter operates by sensing static pressure. If the static pressure source is blocked, there
will be no change in static pressure sensed by the instrument and therefore no change in the
altimeter’s indication.

Question 36

For its operation, the VSI senses
[a] dynamic pressure
[b] rate of change of static pressure
[c] static pressure
[d] rate of change of dynamic pressure

Answer 36

B
In the case of the VSI it is not the actual static pressure that matters so much as the rate at which
the pressure is changing. That is why the VSI continues to give a useful reading when the alternate static source is selected.

Question 37

Force in a hydraulic system is
[a] pressure per unit area
[b] pressure multiplied by area
[c] pressure divided by area
[d] pressure multiplied by velocity

Answer 37

B
In any system force is calculated by multiplying the pressure by the area. A pressure of 10 pounds
per square inch acting on a surface with an area of 5 square inches exerts a force of 50 pounds

Question 38

Pressure in a hydraulic system is defined as
[a] force per unit area
[b] pressure per unit area
[c] pressure acting only along one axis
[d] force multiplied by area

Answer 38

A
If Pressure x Area = Force, it follows that Force ÷ Area = Pressure. That is why pressure is
measured as pounds per square inch or kilograms p

Question 39

Hydraulic fluids are
[a] incompressible
[b] easily compressed
[c] only compressible at pressures over 10000 psi
[d] highly viscous

Answer 39

A
A hydraulic system could not work if the fluid was able to compress. Any liquid is incompress
ible. That is why, when a certain volume of fluid is moved by the pump, the same volume of fluid
flows into the hydraulic cylinder to move the ram.

Question 40

The reservoir in a hydraulic system supplies
[a] emergency system pressure
[b] pressure to the pump
[c] a place to store system fluid when the system is shut down
[d] a reserve of fluid to compensate for minor leaks

Answer 40

D
Theoretically an hydraulic system should work without a reservoir by simply circulating the fluid.
The reservoir provides a back-up supply of fluid to compensate for the inevitable minor leaks.

Question 41

An hydraulic ram may be stopped at any position by
[a] stopping the pump
[b] reversing the selector valve
[c] placing the selector valve in a neutral position
[d] stalling the jack

Answer 41

C
The selector valve has three possible positions. It sends fluid to the bottom of the piston [ram] to
push it one way and to the bottom of the piston to push it the other way. In the neutral position
it prevents fluid from flowing in either direction holding the piston steady.

Question 42

In a hydraulic system using a constant displacement pump, system pressure is controlled by
[a] the accumulator
[b] the reservoir
[c] the pressure regulator
[d] the pressure relief valve

Answer 42

C
The pressure regulator controls a preset system pressure by means of a spring-loaded valve.
When the pressure in the system exceeds the preset level the spring-loaded valve ‘pops’ allowing
the excess fluid to recirculate back to the reservoir.

Question 43

An accumulator may be fitted to a hydraulic system to
[a] boost fluid capacity
[b] provide emergency pressure
[c] replace the pump
[d] cool the fluid

Answer 43

B
The accumulator provides a source of fluid under pressure that can provide limited system operation when the pump is not operating.

Question 44

A non return valve (check valve) is fitted to a hydraulic circuit to
[a] ensure pressure only acts along one axis
[b] ensure fluid is only used once
[c] ensure fluid only flows in one direction
[d] prevent excessive system back pressure

Answer 44

C
There are many positions in the hydraulic circuit where the fluid must be constrained to flowing
in one direction only. The check valve permits flow in one direction but prevents any flow in
the opposite direction.

Question 45

A filter by pass circuit is included in some hydraulic systems to
[a] prevent fluid flow through the filter if it is already clean
[b] relieve filter pressure
[c] keep the fluid flowing in the correct direction
[d] allow fluid to return to the reservoir if the filter becomes blocked

Answer 45

D
It is better to have dirty fluid than none at all! The filter by-pass allows the system to continue to
operate if the filter becomes blocked. Obviously something is seriously wrong if this happens.

Question 46

The purpose of the cooler in an aircraft hydraulic system is to cool the fluid
[a] after it has passed through an actuating ram
[b] as it leaves the reservoir
[c] as it returns from the pressure regulator to the reservoir
[d] as it leaves the accumulator

Answer 46

C
The cooler is situated in the return line.

Question 47

A pressure relief valve fitted to an aircraft hydraulic system is designed to
[a] protect the system from excessive pressure in the event of a pressure regulator failure
[b] relieve pump pressure at times of low demand
[c] provide a vent to allow for thermal expansion
[d] pressurize the accumulator

Answer 47

A
The pressure relief valve is a ‘last resort’ safety system. If the pressure regulator ever failed e.g. the
spring-loaded valve became stuck, the system pressure would rise to dangerous levels and prob
ably cause hydraulic leads to explode unless provision is made for fluid to return to the reservoir.

Question 48

An hydraulic reservoir may be pressurised to provide
[a] extra system pressure
[b] positive fluid supply and reduced foaming
[c] a backup for the pump

Answer 48

B
The reservoir must never be allowed to develop a vacuum above the fluid. A pressurised reservoir
maintains a positive pressure [above outside atmospheric pressure] maintain a good flow of fluid
and to prevent excessive foaming of the fluid.

Question 49

When carrying out a rate-one left turn onto north in the southern hemisphere, the pilot should roll out of the turn on a heading of approximately
[a] 000°M
[b] 015°M
[c] 345°M
[d] 010°M

Answer 49

C
The compass is ‘nippy on north’. During a turn the compass indicates north before the aircraft
actually achieves the heading of north. You should roll out about 15° after north i.e. 345°C.

Question 50

Hydraulic fluid requires which of the following properties?
[a] low flash point
[b] high viscosity
[c] lubricating properties
[d] low thermal stability

Answer 50

C
Apart from the main task of transferring pressure throughout the system, the hydraulic fluid serves
to lubricate the system as well.

Question 51

An unchanged altimeter reading during climb in an aircraft could indicate a
[a] blocked pitot tube
[b] blocked static vent
[c] leak in the pitot line
[d] leak in the static line

Answer 51

B
The altimeter senses static pressure. If static pressure does not change the indication of the
altimeter will not change.

Question 52

The IVSI instrument
[a] gives the pilot latitude and longitude similar to GPS
[b] shows the pilot the current aircraft attitude
[c] shows the pilot the TAS
[d] shows the pilot the immediate rate of climb or descent

Answer 52

D
IVSI stands for Inertial Vertical Speed Indicator. The addition of inertial weights to the instrument
allows it to overcome the problem of lag and indicate a climb or descent almost immediately.

Question 53

De-icing boots should be activated
[a] at all times in cloud above the freezing level
[b] whenever the temperature is below zero
[c] after ice has formed
[d] before entering a region where ice is likely to be encountered

Answer 53

C
As the name suggests, de-icing requires that ice has already formed and is then removed. Anti
icing prevents ice forming in the first place.

Question 54

When carrying out a rate-one turn to the right onto south in the Southern Hemisphere the pilot should roll out of the turn on a heading of approximately
[a] 165°M
[b] 180°M
[c] 195°M
[d] 190°M

Answer 54

A
The compass is ‘sluggish on south’. That means that the pilot must undershoot south i.e. roll out
early. If you are turning to the right you must roll out on a compass heading about 15° before
the compass says south. Roll out on a compass heading of 165°C.

Question 55

At 6000 ft the pitot becomes blocked, but the static vent is still clear. On descent VSI shows
[a] lower than actual ROD
[b] zero
[c] higher than actual ROD
[d] correct ROD

Answer 55

D
Another tricky one! The pitot has nothing to do with the VSI - only the static vent effects it.