Questions and Answers
What occurs when the swash plate of a positive displacement swash plate pump is perpendicular to the axis of the pump?
What is the purpose of the spring in a fuel pump?
At which altitude is the burner fuel flow at its maximum?
How is servo pressure, used to control fuel pump 'Swash Plate' angle, obtained?
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What would happen to the engine if the B.P.C half ball valve in the servo line sticks open?
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Why is an A.C.U fitted to a gas turbine engine?
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What happens to pump output if fuel pump servo pressure is reduced?
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What is the primary function of the metering block in a fuel system?
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What is the primary cause of surge during acceleration in fuel systems?
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What method does the B.P.C use to control the fuel control unit?
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What is the flow condition when the swash plate of a positive displacement pump is perpendicular to the pump's axis?
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At which condition is the burner fuel flow at its maximum?
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Which type of fuel control unit is most commonly found in modern jet engines?
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How is servo pressure for controlling the fuel pump swash plate angle obtained?
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What is the purpose of the Barometric Pressure Control in a turboshaft engine?
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During stable running conditions, how is the spill or half ball valve positioned?
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What is the role of the B.P.C in a gas turbine engine fuel system?
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What must be performed after changing the fuel control unit on an aircraft gas turbine engine?
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What is the function of a kinetic valve in a fuel system?
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How does specific fuel consumption behave at high altitudes?
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What does the attenuator do in the fuel system?
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What is the main function of a hydromechanical governor in fuel control?
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What does a barometric Pressure Controller regulate?
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Why are kinetic valves preferred in certain systems?
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What is the expected effect of increased fuel specific gravity on centrifugal type engine speed governor?
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Which parameter significantly influences the operation of an automatic fuel control unit in turbojet engines?
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Study Notes
Fuel Systems
- If the swash plate of a positive displacement swash plate pump is perpendicular to the axis of the pump, the flow will be zero.
- A spring moves the swash plate away from the minimum stroke position.
- The burner fuel flow is at maximum at I.S.A. sea level.
- Servo pressure, which is used to control fuel pump swash plate angle, is obtained from pump delivery pressure through variable restrictions.
- If the B.P.C half ball valve in the servo line sticks open, it will cause an increase of fuel flow, therefore an increase in RPM.
- An A.C.U is fitted to a gas turbine engine to limit the rate of increase in fuel flow during sudden acceleration.
- If fuel pump servo pressure is reduced, pump output will decrease.
- The B.P.C is fitted in a gas turbine engine fuel system to vary pressure pump output in relation to the pressure variation at the intake.
- A kinetic valve is a device used to control H.P pump output, achieved by movement of a knife blade.
- Specific fuel consumption at altitude will increase.
- During any stabilised running condition, the spill or half ball valve is lightly seated.
- The purpose of the attenuator fitted between the H.P fuel pump and the B.P.C in a fuel system is to damp out pulsations in the fuel delivery to the B.P.C.
- The hydromechanical governor is fitted to a gas turbine engine fuel pump to enable the engine to operate over a wide range of fuel SGs.
- A barometric Pressure Controller controls fuel flow to suit atmospheric pressure changes.
- Kinetic valves are used because they are more sensitive.
- When considering a centrifugal type engine speed governor, an increase in fuel S.G. will cause a reduction in maximum RPM.
- On a FADEC engine, A channel uses a separate winding of the control alternator to B channel.
- Normal fuel/air ratio for successful combustion is 15:1.
- The purpose of the L.P. pump is to prevent cavitation of the H.P. Fuel pump.
- The fuel pump plungers are lubricated by the Fuel.
- Which forces control the maximum RPM governor in a non-hydromechanical swashplate type of pump? Rotor centrifugal pressure opposed to tension spring loading.
- The holes in the body of the duple burner provide air to the shroud around the burner head to minimise carbon formation on the burner face.
- A fuel heater prevents LP filter icing.
- On a FADEC engine, the E.E.C. has electronic control of the hydro-mechanical fuel control unit in all modes.
- During normal running conditions, combustion is self-supporting.
- On a FADEC engine, the channel reset selects standby which becomes active on the next start.
- With a decrease in fuel SG, what is the result when the engine is fitted with an uncompensated fuel governor? Maximum RPM increase.
- The maximum RPM of a turbine engine is limited by reduction of the fuel pump stroke by a spill valve sensitive to centrifugally generated fuel pressure.
- To what condition does the fuel flow respond during aircraft acceleration? Mass airflow rate through the engine.
- During acceleration, the fuel flow is increased at a controlled rate in order to prevent surge and the risk of flame-out.
- The B.P.C controls the F.C.U by pressure sensing.
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Description
Multiple-choice questions about fuel systems, including swash plate pumps and burners.