15.14 engine indication systems

Question 1

what does EGT stand for?

Answer 1

exhaust gas temperature

Question 2

where do we measure EGT?

Answer 2

between high and low pressure turbine or directly behind the low pressure turbine

Question 3

what is TIT and why cant it be measured ?

Answer 3

turbine inlet temp
its too hot so is measured from the EGT

Question 4

what is the temperature indication range for the EGT instrument?

Answer 4

0- 1200 degrees c

Question 5

what are the three types of engine indications?

Answer 5

-performance indications
-system indications
-engine trend monitoring

Question 6

what is another name given for system indications?

Answer 6

secondary indications

Question 7

where might engine trend monitoring be shown?

Answer 7

not typically in the flight deck usually for maintenance purposes

Question 8

what is EPR?

Answer 8

engine pressure ratio, the difference between inlet airspeed and outlet

Question 9

what are examples other performance indicators?

Answer 9

EPR, N2, N1, N3 if applicable, Turbine inlet temp measured from EGT, fuel flow.

Question 10

what is another way that thrust could be represented ?

Answer 10

speed of fan rotation or (N1)

Question 11

what may be included in engine system indications?

Answer 11

engine vibration, oil quantity, oil temp and oil pressure.

Question 12

what are the main parameters measured for engine trend monitoring?

Answer 12

The thermodynamic analysis
The mechanic-dynamic analysis
The oil consumption analysis

Question 13

how is EPR shown?

Answer 13

analogue and/ or digital value

Question 14

what indications will be shown on a typical EPR display?

Answer 14

-blue circle shows position of actual throttle
-green line shows throttle level when autopilot is engaged
-red line shows max available thrust

Question 15

what is the purpose of FLEX take off or assumed temp derate?

Answer 15

it uses an assumed temperature thrust reduction to prevent engine wear

Question 16

where is oil pressure measured?

Answer 16

after the oil pump

Question 17

how is oil pressure measured?

Answer 17

A Bourdon tube can be either c-shaped or helical, with. When the pressure enters the tube, the pressure acts to change the oval to a circular cross section. This causes the tube to move – opening the c-shape The deflection can be measured on a scale

Question 18

what is another way that oil pressure can be measured

Answer 18

a strain gauge operating with a Wheatstone bridge, when no strain is applied the bridge is balanced meaning voltage difference is zero

Question 19

what is the function of the oil pressure switch?

Answer 19

operating on a diaphragm measuring pressure principle it gives a decrease in pressure activates the switch indicating a drop in oil pressure to the cockpit

Question 20

what is the most commonly used types of engine oil temperature sensor?

Answer 20

the Resistance Temperature Detector (RTD) or Thermocouple. An RTD is a sensor made of a temperature-sensitive resistor, while a thermocouple consists of two dissimilar metal wires joined together

Question 21

what is the largest concern with cold fuel?

Answer 21

ice build up

Question 22

what type of fuel temperature sensor is used?

Answer 22

resistance type electric fuel temperature sender in the main fuel tank

Question 23

how can temperature of fuel be adjusted?

Answer 23

low fuel temperature can be corrected with the use of a fuel heater

Question 24

what are the two indications given by the fuel flow indicators?

Answer 24

the actual fuel flow to the engines
The fuel used since the engine was started

Question 25

what is fuel quantity indicated in?

Answer 25

kg, lbs or tons

Question 26

what fundamental law of physics is fuel flow always based on?

Answer 26

Force = Mass x Acceleration

Question 27

what are the most common types of fuel flow transmitters available today?

Answer 27

Synchronous mass flow and motorless mass flow

Question 28

how does the synchronous mass flow transmitters function?

Answer 28

the fuel mass turns a turbine against a spring and the deflection angle is measured. To get the force the fuel must be accelerated. This is achieved by an impeller that rotates continuously, driven by an electric motor

Question 29

how does a motorless mass flow transmitter function?

Answer 29

They use the fuel itself to generate acceleration. In this transmitter type, the fuel flow turns a small turbine. The rotating turbine also drives a drum and an impeller, which is located inside the drum. Both are coupled by a spring.

The fuel drives the turbine, drum, and impeller with a speed that is proportional to the volume of fuel

Question 30

what are engine speeds expressed as?

Answer 30

a percent of top speed

Question 31

how does the variable reluctance sensor function?

Answer 31

a type of electromagnetic sensor which detects a change in the magnetic flux between a magnet and ferromagnetic target the frequency of this is measured

Question 32

how does a tachometer generator function?

Answer 32

The tachometer generator has a permanent magnet that is driven by the gearbox with a speed that is proportional to the N2 rotor speed. The rotating magnetic field generates a 3-phase AC voltage with a frequency that is proportional to the input speed

Question 33

what are the types of speed indication displays?

Answer 33

A display with a clock-type scale
A display with a moving vertical bar
The classical electromechanical indicator

Question 34

what is vibration typically measured in?

Answer 34

numbers 0-6

Question 35

what is the EVMU?

Answer 35

Engine Vibration Monitoring Unit

Question 36

what is typically used to measure engine vibration?

Answer 36

accelerometers -
The electromagnetic accelerometer
The piezoelectric-crystal type sensor

Question 37

how does the piezoelectric-crystal function?

Answer 37

A piezoelectric crystal generates a voltage when you apply a force to the crystal In this sensor, the force is applied by an inertia mass, which presses the crystal against the base plate when the sensor is accelerated

Question 38

what will occur if the N1 or N2 speed signal fails for vibration monitoring?

Answer 38

BB will be shown which is broadband

Question 39

why are toque meters used to measure power being outputted by turboshaft engines?

Answer 39

its not possible to measure with turbine gas temperature and engine RPM

Question 40

what is the structure of a typical torque meter?

Answer 40

to concentric shafts one is a datum shaft only connected to engine output the twist of the other shaft is measured as it is proportional to torque

Question 41

what is the structure of a hydraulic torque meter?

Answer 41

helical ring gear moving in response to applied torque

Question 42

what is a critical test to be performed after engine maintenance?

Answer 42

power assurance test which consists of running the aircraft from 0 to full power and back in a set amount of time

Question 43

after start up on a power assurance test how long should the engine be left to idle?

Answer 43

5 minutes

Question 44

after engine operation above 70 % of N1 how long should the engine be left cool at idle on a power assurance test?

Answer 44

10 minutes