Fuel control unit and Instrument and Measurement

Question 1

What are the different types of fuel control units?

Answer 1

Hydromechanical
Electronic
FADEC (full authority digital engine control)

Question 2

What is the Hydromechanical FCU?

Answer 2

A combination of a flyweight governor and several sensors including a compressor discharge pressure, the burner can pressure, and exhaust pipe pressure.
In some cases, the engine’s fuel pump is integrated to the FCU.

Question 3

What is the electronic engine control FCU (EEC)?

Answer 3

A hydromechanical fuel control but with added electrical components to prevent overheating or overspeeding the engine. If the electrical part of the control should fail it will revert to a standard hydromechanical FCU

Question 4

What is the FADEC FCU?

Answer 4

A digital computer that controls a servo-operated fuel valve. In this case, the power lever is only electrically connected to the fuel control.

Question 5

How is torque indicated?

Answer 5

• Indicates power on a turbo prop
• Displayed in (psi, ft/lbs, Percentage, Horsepower)
• Hydromechanical type
• Electronic type

Question 6

What is turbine temperature?

Answer 6

Indicates the most critical temperature

Done by thermocouple probes mounted in the gas stream

Question 7

How is temperature sensed in the oil?

Answer 7

• Torquemeter pressure transmitter
• Chip detector
• Temp and pressure as one or separate transmitters

Question 8

How is fuel flow indicated?

Answer 8

• Fuel flow gives an indication of fuel burn and flow is measured electrically and sent to an indicator, or to pfd

Question 9

How are vibrations indicated?

Answer 9

• By piezoelectric accelerometers are mounted around the engine, any vibration will cause a signal this will be digitized and sent to controls