15.11 Flashcards
Two sections of aircraft fuel system?
Airframe (primary) stores the fuel
Engine (secondary)
What is the purpose of the secondary fuel system?
Supply fuel to combustion chamber
Also controls quantity of fuel necessary for all operating conditions
Two subsystems of fuel systems?
Fuel distribution subsystem
Fuel control subsystem
The low pressure pump ensure the high pressure pump doesn’t do what?
Draw fuel from fuel tanks by suction and also prevents cavitation
The high pressure pump produces what pressure?
900 Psi
Overpressure relief valve operates at what pressure?
1250 psi
Bypassed fuel can be used to do what?
Cool the Integrated drive generator oil cooler
In low engine power conditions the hot bypass return fuel does what?
Heats up the fuel from the low pressure pump too much
Results in engine oil not cooling sufficiently
The fuel control unit of an engine is usually mounted to what?
Engine fuel pump on accessory gearbox
Two types of fuel control systems? Which is old and which is new?
Speed governed fuel control units-Old
Constant thrust fuel control units-Modern
The pipes and push pull cables in fuel control units are needed to transmit what signals?
Throttle demand signal
Temperature signal
Pressure signal
Speed feedback signal
The N2 speed feedback signal is usually transmitted how?
Via a mechanical drive shaft from main fuel pump
The N1 speed feedback signal is what type of signal and where does it come from?
Fuel pressure signal
Comes from hydro mechanical N1 sensor
How do hydromechanical temperature sensors work?
Convert air temperature to fuel pressure signals
Two major sections of fuel control unit? What are they further split into?
Fuel metering section
Computing section
Further split into:
Governing section
Limiting section
