Powerplant And System Monitoring Instruments

Question 1

Temp sensors
1-How do thermocouple temperature systems work
2-which junction is used as a reference
3-which junction is used to measure

Answer 1

1-Thermocouples are thermoelectric sensors that consist of 2 junctions of dissimilar metals, when 2 junctions are at diff temps, voltage developed accross the junction
2-the cold junction, kept at constant temp
3-the hot junction

Question 2

What does a wheat stone bridge temperature system consist of and how does it operate

Answer 2

Bridge circuit consists of 3 fixed resistors and a veriable resistor which is the temperature probe
Probe contains nickel wire, as temp of probe increases, current flows in bridge which drives a needle on a gauge

Question 3

1-what is MAP a measure of
2-what is it an indication of
3-what instrument is used to measure pressure in the MAP

Answer 3

1-Absolute pressure of air in engine induction manifold
2-power being developed
3-a diaphragm(aneroid capsule)

Question 4

1-what does EPR measure
2-what does EPR indicate
3-what type of gauge is used to measure it
4-how does the EPR transmitter indicate the EPR on the gauge

Answer 4

1-it compares total exhaust pressure to pressure of RAM air at inlet of engine
2-indicates thrust being developed by engine
3-it uses a remote sensing instrument that receives input from EPR transmitter/in digital displays, a computer
4-EPR transmitter contains bellows that compares and converts the ratio into electric signal

Question 5

1-what pressure gauges do light a/c use
2-what type of pressure gauge do more complex a/c use
3-where does the differential pressure gauge measure from, what device is used

Answer 5

1-bouron tubes
2-uses a sensor with a transducer which sends electrical signals to cockpit
3-compares fuel inlet pressure to aid pressure at fuel metering device, using a bellows type gauge

Question 6

1-what is used to measure CHT
2-what is used to measure EGT

Answer 6

1-thermocouples with gauge positioned in cold junction
2-a thermocouple that uses a probe to measure EGT

Question 7

1-What is used to measure fuel temperature
2- how is the data transmitted

Answer 7

1-Variable resistors with sensitive element contained in a bulb with fluid
2- by a wheatstone Bridge arrangement to a gauge in the cockpit

Question 8

1- how is a mechanical tachometer connected to the engine
2-how does the mechanical tachometer work

Answer 8

1-via flexible shaft
2- the shaft rotates a magnet within the inductor casing. The rotating magnets sets up Eddie currents in a cup which have the own Magnetic fields. The resultant rotating magnetic field causes a spring restrained rotor to attempt to follow the rotating field

Question 9

What is the formula for working out capacitance in a capacitance type fuel gauge

Answer 9

Capacitance = E × A/D
Where:
E=dielectric permittivity
D=distance between plates
A=area of plates