Fuel Systems Quiz

Questions and Answers

What occurs when the swash plate of a positive displacement swash plate pump is perpendicular to the axis of the pump?

The flow remains constant

The flow increases

The flow is zero (correct)

The flow reverses

What is the purpose of the spring in a fuel pump?

To move the swash plate away from the minimum stroke position (correct)

To move the swash plate towards the minimum stroke position

To maintain a constant fuel flow

To reduce servo pressure

At which altitude is the burner fuel flow at its maximum?

10°C above I.S.A. sea level

I.S.A. sea level (correct)

Low altitude

High altitude

How is servo pressure, used to control fuel pump 'Swash Plate' angle, obtained?

From pump delivery pressure through variable restrictions Signup and view all the answers

What would happen to the engine if the B.P.C half ball valve in the servo line sticks open?

An increase of fuel flow, resulting in an increase in RPM Signup and view all the answers

Why is an A.C.U fitted to a gas turbine engine?

To limit the rate of increase in fuel flow during sudden acceleration Signup and view all the answers

What happens to pump output if fuel pump servo pressure is reduced?

It decreases Signup and view all the answers

What is the primary function of the metering block in a fuel system?

To regulate fuel flow Signup and view all the answers

What is the primary cause of surge during acceleration in fuel systems?

Over fueling Signup and view all the answers

What method does the B.P.C use to control the fuel control unit?

Pressure sensing Signup and view all the answers

What is the flow condition when the swash plate of a positive displacement pump is perpendicular to the pump's axis?

Zero flow Signup and view all the answers

At which condition is the burner fuel flow at its maximum?

At I.S.A. sea level Signup and view all the answers

Which type of fuel control unit is most commonly found in modern jet engines?

Hydro-mechanical Signup and view all the answers

How is servo pressure for controlling the fuel pump swash plate angle obtained?

From pump delivery pressure through variable restrictions Signup and view all the answers

What is the purpose of the Barometric Pressure Control in a turboshaft engine?

To vary pressure pump output based on air pressure at the intake Signup and view all the answers

During stable running conditions, how is the spill or half ball valve positioned?

Lightly seated Signup and view all the answers

What is the role of the B.P.C in a gas turbine engine fuel system?

To vary pressure pump output in relation to the pressure variation at the intake. Signup and view all the answers

What must be performed after changing the fuel control unit on an aircraft gas turbine engine?

You must retrim the engine. Signup and view all the answers

What is the function of a kinetic valve in a fuel system?

To control H.P pump output using a knife blade mechanism. Signup and view all the answers

How does specific fuel consumption behave at high altitudes?

It increases due to lower atmospheric pressure. Signup and view all the answers

What does the attenuator do in the fuel system?

It damps out pulsations in the fuel delivery. Signup and view all the answers

What is the main function of a hydromechanical governor in fuel control?

To accommodate a wide range of fuel densities. Signup and view all the answers

What does a barometric Pressure Controller regulate?

Fuel flow to adapt to changes in air density. Signup and view all the answers

Why are kinetic valves preferred in certain systems?

They are more sensitive to control changes. Signup and view all the answers

What is the expected effect of increased fuel specific gravity on centrifugal type engine speed governor?

It will lead to a decrease in maximum RPM. Signup and view all the answers

Which parameter significantly influences the operation of an automatic fuel control unit in turbojet engines?

Burner pressure. Signup and view all the answers

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.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Multiple-choice questions about fuel systems, including swash plate pumps and burners.