Sensors and Instruments

Question 1

The EPR is computed by:

Answer 1

dividing turbine discharge pressure by compressor inlet pressure.

Question 2

The position error of the static vent on which the altimeter is connected varies substantially with the:

Answer 2

Mach number of the aircraft

Question 3

The density altitude is :

Answer 3

the altitude of the standard atmosphere on which the density is equal to the actual density of the atmosphere

Question 4

When an aircraft has turned 90 degrees with a constant attitude and bank, the pilot observes the following on a classic artificial horizon :

Answer 4

too much nose-up and bank too low

Question 5

A gravity type erector is used in a vertical gyro device to correct errors on:

Answer 5

an artificial horizon

Question 6

The QNH is by definition the value of the:

Answer 6

altimeter setting so that the altimeter, on the apron of the aerodrome for which it is given, reads the elevation.

Question 7

In a standard atmosphere and at the sea level, the equivalent airspeed (EAS) is:

Answer 7

equal to the true airspeed (TAS).

Question 8

A thermocouple type thermometer consists of:

Answer 8

two metal conductors of different type connected at two points.

Question 9

One of the disadvantages of an electronic tachometer is the:

Answer 9

necessity of a power supply.

Question 10

The principle of capacity gauges is based on the capacitance variation of:

Answer 10

a capacitor with the type of dielectric.

Question 11

A synchroscope is used on aircraft to:

Answer 11

set several engines to the same speed.

Question 12

Modern low altitude radio altimeters emit waves in the following frequency band:

Answer 12

SHF (Super High Frequency).

Question 13

The operating frequency range of a low altitude radio altimeter is:

Answer 13

4200 MHz to 4400 MHz.

Question 14

The “Bourdon tube” is used to measure:

Answer 14

pressure.

Question 15

Given: M is the Mach number Ts is the static temperature Tt is the total temperature

Answer 15

Ts = Tt /(1+0.2. M²)

Question 16

A pilot wishes to turn left on to a southerly heading with 20° bank at a latitude of 20° North. Using a direct reading compass, in order to achieve this he must stop the turn on an approximate heading of:

Answer 16

160°

Question 17

If a manifold pressure gauge consistently registers atmospheric pressure, the cause is probably;

Answer 17

leak in pressure gauge line.

Question 18

The operation of the radio altimeter of a modern aircraft is based on:

Answer 18

frequency modulation of the carrier wave.

Question 19

In an engine vibration monitoring system for a turbojet any vibration produced by the engine is:

Answer 19

amplified and filtered before being fed to the cockpit indicator.

Question 20

In order to measure temperature the cylinder head temperature (CHT) gauge utilises a:

Answer 20

thermocouple consisting of two dissimilar metals.

Question 21

According to the range of pressure to be measured (low, medium, high), different types of pressure sensors are used.
Classify the following sensors by order of increasing pressure for which they are suitable:
1- bellows type
2- Bourdon tube type
3- aneroid capsule:

Answer 21

3,1,2

Question 22

The signal supplied by a transmitter fitted with a 3-phase AC generator, connected to RPM indicator, is:

Answer 22

a three-phase voltage, the frequency of which varies with the RPM; the indicator is provided with a motor which drives a magnetic tachometer

Question 23

The signal supplied by a transmitter fitted with a magnetic sensor, connected to an RPM indicator is:

Answer 23

an AC voltage, the frequency of which varies with the RPM; the indicator converts the signal into square pulses which are then counted

Question 24

A vibration indicator receives a signal from different sensors (accelerometers). It indicates the:

Answer 24

vibration amplitude at a given frequency

Question 25

The transmitter of RPM indicator may consist of :
1- a magnetic sensor supplying an induced AC voltage
2- a DC generator supplying a DC voltage
3- a single-phase AC generator supplying an AC voltage
4- a three-phase AC generator supplying a three-phase voltage
The combination of correct statements is :

Answer 25

1,2,3,4

Question 26

The indication of a fuel float gauge varies with:
1 - pitch attitude
2 - accelerations
3 - fuel temperature
The combination that regroups all of the correct statements is:

Answer 26

1, 2, 3.

Question 27

The float type fuel gauges provide information on:

Answer 27

volume with the result that the indication varies with the temperature of the fuel.

Question 28

The sensors used to measure the exhaust gas temperature on an aircraft equipped with gas turbine engine are:

Answer 28

thermocouples.

Question 29

The measurement of the turbine temperature or of the EGT is carried out at the:

Answer 29

outlet of the high pressure stage of the turbine.

Question 30

A Full Authority Digital Engine Control (FADEC) has the following functions :
1- flow regulation (fuel, decelerations and accelerations monitoring)
2- automatic starting sequence
3- transmissions of engine data to the pilot’s instruments
4- thrust management and protection of operation limits
5- monitoring of the thrust reversers
The combination regrouping all the correct statements is:

Answer 30

1, 2, 3, 4, 5

Question 31

In a 3-phase synchronous motor type tachometer indicator :
1- the transmitter is a direct current generator
2- the voltage is proportional to the transmitter drive speed
3- the frequency is proportional to the transmitter drive speed
4- the speed indicating element is a galvanometer
5. the speed indicating element is an asynchronous motor driving a magnetic tachometer
The combination regrouping all the correct statements is:

Answer 31

3, 5

Question 32

The disavantages of an “electric” fuel (float) gauge are :
1- the design is complex
2- the indications are influenced by the airplane attitude variations
3- the indications are influenced by the accelerations
4- the indications are influenced by temperature variations
5- that an alternative current supply is necessary
The combination regrouping all the correct statements is :

Answer 32

2, 3, 4

Question 33

The aeroplane outside air temperature probe measures the:

Answer 33

total air temperature minus kinetic heating effects in order to obtain the static temperature.

Question 34

The probe used to measure the air intake pressure of a gas turbine engined powerplant is:

Answer 34

an aneroid capsule.

Question 35

A millivoltmeter measuring the electromotive force between the “hot junction” and the “cold junction” of a thermocouple can be directly graduated in temperature values provided that the temperature of the:

Answer 35

cold junction is maintained constant.

Question 36

The gauge indicating the quantity of fuel measured by a capacity gauging system can be graduated directly in weight units because the dielectric constant of fuel is:

Answer 36

twice that of air and varies directly with density.

Question 37

When compared with the volumetric fuel flowmeter, the mass fuel flowmeter takes into account the fuel:

Answer 37

density.

Question 38

The advantages of an electrical induction tachometer are:
1- the display is not sensitive to line resistance
2- the measurement is independent of aircraft power supply
3- the measurement is independent of temperature variations
4- the option to use without restriction several indicators connected in parallel to a single transmitter
The combination regrouping all the correct statements is:

Answer 38

1, 2, 4.

Question 39

The electronic tachometer sensor is composed of:

Answer 39

a notched wheel rotating in front of an electro-magnet.

Question 40

The advantages of a D.C. generator tachometer are:
1- easy transmission of the information.
2- independence of the information relative to the airborne electrical power supply.
3- freedom from any spurious current due to the commutator.
The combination regrouping all the correct statements is:

Answer 40

1, 2.