Swash Plate Pump Operations

Questions and Answers

What is the primary purpose of cross-feeding fuel from one tank to another?

To balance fuel levels in both tanks

To supply fuel to the engines (correct)

To reduce fuel pressure in the system

To prevent engine failure

What controls the swash plate in the fuel pump of an axial flow gas turbine engine?

Servo hydraulic pressure

Manual control

Electrical servo control

Servo fuel pressure (correct)

Why are the end fittings on a fuel non-return valve normally of different sizes?

To allow a full fuel flow through the valve

To increase fuel pressure

To facilitate bleeding the system

To prevent incorrect installation (correct)

What type of sensors does the E.E.C receive signals from?

Pressure and temperature sensors Signup and view all the answers

When does the E.E.C channel change over occur?

On engine start up Signup and view all the answers

What is the possible combined output from all the scavenge pumps in a lubrication system?

Greater than the pressure pump output Signup and view all the answers

What happens when the knife-edge blade in a kinetic valve is fully in?

Servo pressure is being bled off Signup and view all the answers

What is the purpose of servo fuel pressure in an axial flow gas turbine engine?

To control the swash plate Signup and view all the answers

What type of valve is a fuel non-return valve also known as?

Check valve Signup and view all the answers

What is the function of the E.E.C in a modern FADEC system?

To receive signals from sensors Signup and view all the answers

What is the function of cross-feeding fuel from one tank to another in a gas turbine engine?

To supply fuel to the engines Signup and view all the answers

What type of pressure controls the swash plate in the fuel pump of an axial flow gas turbine engine?

Servo fuel pressure Signup and view all the answers

Why are the end fittings on a fuel non-return valve designed to be different sizes?

To prevent incorrect installation Signup and view all the answers

What type of signals does the E.E.C receive in a modern FADEC system?

Pressure and temperature sensors Signup and view all the answers

Under what condition does the E.E.C channel change over occur?

On engine start up Signup and view all the answers

What is the relationship between the combined output from all the scavenge pumps in a lubrication system and the pressure pump output?

The combined output is greater than the pressure pump output Signup and view all the answers

What happens when the knife-edge blade in a kinetic valve is fully in?

Servo pressure is being bled off Signup and view all the answers

What is the purpose of servo fuel pressure in an axial flow gas turbine engine?

To control the swash plate in the fuel pump Signup and view all the answers

What is the function of the E.E.C in a modern FADEC system?

To receive signals from sensors Signup and view all the answers

What type of valve is the fuel non-return valve also known as?

Check valve Signup and view all the answers

What happens to the fuel flow when the swash plate of a positive displacement swash plate pump is perpendicular to the axis of the pump?

It becomes zero Signup and view all the answers

What is the purpose of a spring in a positive displacement swash plate pump?

To move the swash plate away from the minimum stroke position Signup and view all the answers

At what altitude is the burner fuel flow at maximum?

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

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

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

What would be the effect on the engine if the B.P.C half ball valve in the servo line sticks open?

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

What is the purpose of an A.C.U fitted to a gas turbine engine?

It limits the rate of increase in fuel flow during sudden acceleration Signup and view all the answers

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

It decreases Signup and view all the answers

What is the effect of reducing the swash plate angle in a positive displacement pump?

A decrease in fuel flow Signup and view all the answers

What is the function of the barometric Pressure Controller in a gas turbine engine fuel system?

To regulate fuel flow to suit atmospheric pressure changes Signup and view all the answers

What is the purpose of the attenuator in a fuel system?

To dampen pulsations in fuel delivery to the BPC Signup and view all the answers

What is the effect of an increase in fuel S.G. on a centrifugal type engine speed governor?

A reduction in maximum RPM Signup and view all the answers

What is the main purpose of the low-pressure pump in a gas turbine engine?

To prevent cavitation of the high-pressure fuel pump Signup and view all the answers

What is the normal fuel-to-air ratio for successful combustion in a gas turbine engine?

15:1 Signup and view all the answers

How are the fuel pump plungers lubricated?

With the fuel itself Signup and view all the answers

What influences the operation of an automatic fuel control unit on a turbojet engine?

Mixture control position Signup and view all the answers

What controls the maximum RPM governor in a non-hydromechanical swashplate type of pump?

Rotor centrifugal pressure opposed to tension spring loading Signup and view all the answers

Why is a hydromechanical governor fitted to a gas turbine engine fuel pump?

To enable the engine to operate over a wide range of fuel SGs Signup and view all the answers

Why do 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 Signup and view all the answers

What is the purpose of the BPC in a gas turbine engine fuel system?

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

What is prevented by a fuel heater?

Low-pressure filter icing Signup and view all the answers

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

To control H.P. pump output Signup and view all the answers

What type of control does the E.E.C have on the hydro-mechanical fuel control unit in a FADEC engine?

Electronic control in all modes Signup and view all the answers

What must be done after the fuel control unit has been replaced on an aircraft gas turbine engine?

Retrim the engine Signup and view all the answers

Specific fuel consumption at altitude will:

Increase Signup and view all the answers

During normal running conditions, what type of combustion is supported?

Self-supporting combustion Signup and view all the answers

What happens when the channel reset function is activated on a FADEC engine?

The standby channel becomes active on the next start Signup and view all the answers

What is the result of a decrease in fuel specific gravity when the engine is fitted with an uncompensated fuel governor?

Maximum RPM increase Signup and view all the answers

To what condition does the fuel flow respond during aircraft acceleration?

Mass airflow rate through the engine Signup and view all the answers

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

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

What happens to the fuel flow when the swash plate of a positive displacement swash plate pump is perpendicular to the axis of the pump?

The fuel flow is zero Signup and view all the answers

Why is it necessary to control fuel supply to the engine during rapid acceleration?

To prevent excessively high EGT and possible compressor surge Signup and view all the answers

What type of fuel control unit is most commonly used in modern jet engines?

Hydro-mechanical Signup and view all the answers

During any stabilised running condition, the spill or half ball valve is typically:

Lightly seated Signup and view all the answers

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

To control HP pump output Signup and view all the answers

What is the purpose of the Barometric Pressure Control unit in a gas turbine engine?

To correct for air density effects on fuel/air mixture Signup and view all the answers

When is the burner fuel flow at maximum?

At ISA sea level Signup and view all the answers

What is the purpose of over fuelling during acceleration in a jet engine?

To prevent compressor surge Signup and view all the answers

What is the orientation of the swash plate in a fuel pump when static?

In the maximum position Signup and view all the answers

What is the primary function of the high-pressure fuel pump in a gas turbine engine?

To provide the majority of the fuel pressure to the engine Signup and view all the answers

What is the position of the pressurization valve and the dump valve in a jet engine fuel system when the engine is shut down?

Pressurization valve open, dump valve open Signup and view all the answers

Which of the following weighs the most?

100 parts of dry air Signup and view all the answers

What does a mixture ratio of 11:1 normally refer to?

1 part fuel to 11 parts air Signup and view all the answers

For what primary purpose is a turbine engine fuel control unit trimmed?

To obtain maximum thrust output when desired Signup and view all the answers

What type of fuel control is used on most of today's turbine engines?

Hydromechanical or electronic Signup and view all the answers

Under which of the following conditions will the trimming of a turbine engine be most accurate?

No wind and low moisture Signup and view all the answers

What receives signals from the E.E.C?

HMU Signup and view all the answers

When trimming a turbine engine, the fuel control is adjusted to?

Set idle RPM and maximum speed or EPR Signup and view all the answers

What is the purpose of a supervisory electronic engine control (E.E.C)?

To adjust a standard hydromechanical fuel control unit to obtain the most effective engine operation Signup and view all the answers

What is the main purpose of the H.P fuel pump in a FADEC system?

To maintain about 40 psi to the inlet of the H.P pump Signup and view all the answers

What happens when Channel A fails to receive information from a sensor in a FADEC system?

Channel A will take the information from channel B Signup and view all the answers

How is fuel flow controlled in a FADEC engine with a hydromechanical fuel system?

By electro-hydraulic servo valves (E.H.S.Vs) Signup and view all the answers

What should the RPM be on approach for maximum acceleration in a FADEC engine?

Above the minimum idle Signup and view all the answers

What happens when the air data inputs to the FADEC E.C.U fail?

The E.C.U reverts to the fail-safe mode Signup and view all the answers

What is the primary function of a fuel heater in a FADEC system?

To prevent entrained water in fuel from freezing Signup and view all the answers

When re-light is required in flight on a FADEC engine, what happens to the igniter?

The igniter is selected automatically Signup and view all the answers

Where is the fuel heater typically located in the fuel system?

Before the LP fuel filter Signup and view all the answers

What provides primary power to the E.E.C in a FADEC system?

Separate permanent magnet alternator Signup and view all the answers

How is the fuel trimmer operated on a turbo-prop engine?

Automatically controlled in conjunction with FCU Signup and view all the answers

What causes the fuel divider valve to open in a turbine engine duplex fuel nozzle?

Fuel pressure Signup and view all the answers

What is the purpose of the flow divider in a turbine engine duplex fuel nozzle?

Creates the primary and secondary fuel supplies Signup and view all the answers

Where is the engine fuel shutoff valve usually located?

Downstream of the engine driven fuel pump Signup and view all the answers

What happens when both FADEC channels are healthy?

They alternate on each engine start Signup and view all the answers

What is the purpose of the LP fuel pump?

To ensure the H.P fuel pump does not cavitate Signup and view all the answers

What is the principal advantage of the duplex fuel nozzle used in many turbine engines?

Provides better atomization and uniform flow pattern Signup and view all the answers

What safety backup is available for the engine fuel flow if the valve on a vane type fuel flow measuring device becomes stuck?

A differential pressure bypass valve Signup and view all the answers

What is the purpose of the supervisory E.E.C?

To send its output to the H.M.U/F.F.G Signup and view all the answers

What happens if a FADEC loses its ADC input?

It goes into soft reversion Signup and view all the answers

What is the primary purpose of an E.E.C?

To save fuel, reduce crew workload, and reduce maintenance costs Signup and view all the answers

What is the purpose of an acceleration control unit in a gas turbine engine?

To limit the rate of increase of fuel flow Signup and view all the answers

What is the function of trimming in a FADEC engine?

Adjusting idle speed and maximum thrust Signup and view all the answers

How are fuel boost pumps typically cooled?

Using fuel Signup and view all the answers

What is the purpose of baffles in a rigid fuel tank?

To prevent surge Signup and view all the answers

What does the E.E.C measure in a FADEC system?

Pressure and Temperature Signup and view all the answers

How are the power supply windings for channel A and Channel B wound in a FADEC system?

On one generator with two separate windings Signup and view all the answers

What happens if an Engine FADEC system loses air-data permanently?

The pilot will switch to Alt on the relevant E.E.C Signup and view all the answers

What is the advantage of F.A.D.E.C?

Reduced pilot workload and maximum efficiency of performance Signup and view all the answers

What is the main purpose of the fuel trimmer unit in a FADEC engine?

To adjust idle speed and maximum thrust Signup and view all the answers

What type of filter is used on the inlet side of a fuel pump?

Wire mesh filter Signup and view all the answers

What is the purpose of the throttle unit in a gas turbine engine fuel system?

To prevent compressor surge and overheating Signup and view all the answers

What happens to the pressure drop across the Fuel Control Unit throttle orifice when the throttle is selected to increase power?

Decreases then increases due to increasing pump output Signup and view all the answers

What happens when the E.E.C supervisory circuit senses a fault on the engine?

The fault annunciator light will be on and the E.E.C will remove fuel, down trimming signal immediately Signup and view all the answers

What is the forward idle setting of the thrust lever resolver angle in a FADEC engine?

40 degrees Signup and view all the answers

What does the E.E.C control in-flight?

Fuel flow Signup and view all the answers

What is not controlled by a FADEC?

Automatic control of engine fire bottles Signup and view all the answers

What consists of a FADEC?

Electronic controls, sensors and an H.M.U Signup and view all the answers

What prevents fuel from spilling out of fuel tank vents during aerobatic manoeuvres?

Float operated valves Signup and view all the answers

What is the purpose of a silver strip on a fuel filter?

To detect sulphur in fuel Signup and view all the answers

What is the basic concept of an H.P fuel control?

Automatic adjustment of the fuel control unit by preventing excess fuel reaching the burners Signup and view all the answers

What is the primary function of servo fuel pressure in an axial flow gas turbine engine?

To control the swash plate angle Signup and view all the answers

Why are the end fittings on a fuel non-return valve normally different sizes?

To prevent incorrect installation Signup and view all the answers

What type of signals does the E.E.C receive in a modern FADEC system?

RPM, pressure, and temperature sensor signals Signup and view all the answers

What happens when the knife-edge blade in a kinetic valve is fully in?

Servo pressure is being bled off Signup and view all the answers

What is the possible combined output from all the scavenge pumps in a lubrication system?

Greater than the pressure pump output Signup and view all the answers

What happens during engine start-up in a FADEC system?

E.E.C channel change over is prepared Signup and view all the answers

What is the function of the E.E.C in a modern FADEC system?

To receive and process sensor signals Signup and view all the answers

What is the purpose of cross-feeding fuel from one tank to another?

To supply fuel to the engines Signup and view all the answers

Study Notes

Swash Plate Pump

If the swash plate is perpendicular to the axis of the pump, the flow will be zero
The swash plate angle is controlled by servo pressure, which is obtained from pump delivery pressure through variable restrictions
A spring moves the swash plate away from the minimum stroke position

Fuel System

The burner fuel flow is at maximum at sea level (ISA)
Fuel flow responds to mass airflow rate through the engine during aircraft acceleration
Fuel flow is increased at a controlled rate during acceleration to prevent surge and the risk of flame-out
The barometric pressure controller (BPC) controls fuel pump output in relation to the pressure variation at the intake

Fuel Pump

The high-pressure fuel pump is fitted in a gas turbine engine aircraft to provide the majority of the fuel pressure to the engine
The low-pressure pump prevents cavitation of the high-pressure fuel pump
The fuel pump plungers are lubricated by the fuel itself

Governor

The hydromechanical governor is fitted to a gas turbine engine fuel pump to enable the engine to operate over a wide range of fuel specific gravities
The governor controls the maximum RPM of the engine by reducing the fuel pump stroke when maximum RPM is reached

Fuel Control Unit (FCU)

The FCU is trimmed to obtain maximum thrust output when desired
The FCU is adjusted to set idle RPM and maximum speed or EPR
Trimming is most accurate in no wind and low moisture conditions

Electronic Engine Control (EEC)

The EEC receives engine operating information and adjusts a standard hydromechanical fuel control unit to obtain the most effective engine operation
The EEC is a system that controls engine operation according to ambient temperature, pressure, and humidity

FADEC System

FADEC (Full Authority Digital Engine Control) system has electronic control of the hydro-mechanical fuel control unit in all modes
Active control switchover occurs on engine start-up only
Channel reset selects standby, which becomes active on the next start

Fuel Nozzle

The duplex fuel nozzle provides better atomization and uniform flow pattern
The flow divider in a turbine engine duplex fuel nozzle creates the primary and secondary fuel supplies
The valve on a vane type fuel flow measuring device becomes stuck, and a differential pressure bypass valve is the safety backup available for the engine fuel flow### Engine Fuel Shutoff Valve
Located downstream of the engine driven fuel pump

FADEC System

Consists of H.M.U, sensors, and an E.E.C
Primary purpose is to save fuel, reduce crew workload, and reduce maintenance costs
Receives primary power from a separate permanent magnet alternator
E.E.C measures pressure and temperature along with RPM
Can change digital inputs into analogue format to provide glass cockpit information and reduce flight crew workload
Has an automatic starting capability
Does not have automatic control of engine fire bottles

Throttle and Fuel Control

Throttle position is controlled by the crew or autothrottle
Fuel flow is controlled by the E.E.C in flight
Trimming is adjusting idle speed and maximum thrust
Fuel trimmer unit is adjusted automatically at altitude

FADEC Channels

Both channels are operating, but either one can be in command if they are both healthy
If a channel fails to receive information from a sensor, it will take the information from the other channel
If all air data input fails, the E.C.U reverts to an alternate (Fail-safe) mode

Engine Performance

Optimized performance is the reason FADEC was introduced
FADEC ensures efficiency is always maximum

Fuel System

Engine fuel pump has a wire mesh filter
Pressure drop across the Fuel Control Unit throttle orifice drops then increases due to increasing pump output
Fuel boost pumps are cooled using fuel
Main purpose of the fuel boost pumps is to provide fuel pressure to both engine pumps

Sensors and Valves

Silver strip on a fuel filter detects sulphur in fuel
Baffles in a rigid fuel tank prevent surge
End fittings on a fuel non-return valve are different sizes to prevent incorrect installation

Swash Plate Pump

If the swash plate is perpendicular to the axis of the pump, the flow will be zero
The swash plate angle is controlled by servo pressure, which is obtained from pump delivery pressure through variable restrictions
A spring moves the swash plate away from the minimum stroke position

Fuel System

The burner fuel flow is at maximum at sea level (ISA)
Fuel flow responds to mass airflow rate through the engine during aircraft acceleration
Fuel flow is increased at a controlled rate during acceleration to prevent surge and the risk of flame-out
The barometric pressure controller (BPC) controls fuel pump output in relation to the pressure variation at the intake

Fuel Pump

The high-pressure fuel pump is fitted in a gas turbine engine aircraft to provide the majority of the fuel pressure to the engine
The low-pressure pump prevents cavitation of the high-pressure fuel pump
The fuel pump plungers are lubricated by the fuel itself

Governor

The hydromechanical governor is fitted to a gas turbine engine fuel pump to enable the engine to operate over a wide range of fuel specific gravities
The governor controls the maximum RPM of the engine by reducing the fuel pump stroke when maximum RPM is reached

Fuel Control Unit (FCU)

The FCU is trimmed to obtain maximum thrust output when desired
The FCU is adjusted to set idle RPM and maximum speed or EPR
Trimming is most accurate in no wind and low moisture conditions

Electronic Engine Control (EEC)

The EEC receives engine operating information and adjusts a standard hydromechanical fuel control unit to obtain the most effective engine operation
The EEC is a system that controls engine operation according to ambient temperature, pressure, and humidity

FADEC System

FADEC (Full Authority Digital Engine Control) system has electronic control of the hydro-mechanical fuel control unit in all modes
Active control switchover occurs on engine start-up only
Channel reset selects standby, which becomes active on the next start

Fuel Nozzle

The duplex fuel nozzle provides better atomization and uniform flow pattern
The flow divider in a turbine engine duplex fuel nozzle creates the primary and secondary fuel supplies
The valve on a vane type fuel flow measuring device becomes stuck, and a differential pressure bypass valve is the safety backup available for the engine fuel flow### Engine Fuel Shutoff Valve
Located downstream of the engine driven fuel pump

FADEC System

Consists of H.M.U, sensors, and an E.E.C
Primary purpose is to save fuel, reduce crew workload, and reduce maintenance costs
Receives primary power from a separate permanent magnet alternator
E.E.C measures pressure and temperature along with RPM
Can change digital inputs into analogue format to provide glass cockpit information and reduce flight crew workload
Has an automatic starting capability
Does not have automatic control of engine fire bottles

Throttle and Fuel Control

Throttle position is controlled by the crew or autothrottle
Fuel flow is controlled by the E.E.C in flight
Trimming is adjusting idle speed and maximum thrust
Fuel trimmer unit is adjusted automatically at altitude

FADEC Channels

Both channels are operating, but either one can be in command if they are both healthy
If a channel fails to receive information from a sensor, it will take the information from the other channel
If all air data input fails, the E.C.U reverts to an alternate (Fail-safe) mode

Engine Performance

Optimized performance is the reason FADEC was introduced
FADEC ensures efficiency is always maximum

Fuel System

Engine fuel pump has a wire mesh filter
Pressure drop across the Fuel Control Unit throttle orifice drops then increases due to increasing pump output
Fuel boost pumps are cooled using fuel
Main purpose of the fuel boost pumps is to provide fuel pressure to both engine pumps

Sensors and Valves

Silver strip on a fuel filter detects sulphur in fuel
Baffles in a rigid fuel tank prevent surge
End fittings on a fuel non-return valve are different sizes to prevent incorrect installation

Swash Plate Pump

If the swash plate is perpendicular to the axis of the pump, the flow will be zero
The swash plate angle is controlled by servo pressure, which is obtained from pump delivery pressure through variable restrictions
A spring moves the swash plate away from the minimum stroke position

Fuel System

The burner fuel flow is at maximum at sea level (ISA)
Fuel flow responds to mass airflow rate through the engine during aircraft acceleration
Fuel flow is increased at a controlled rate during acceleration to prevent surge and the risk of flame-out
The barometric pressure controller (BPC) controls fuel pump output in relation to the pressure variation at the intake

Fuel Pump

The high-pressure fuel pump is fitted in a gas turbine engine aircraft to provide the majority of the fuel pressure to the engine
The low-pressure pump prevents cavitation of the high-pressure fuel pump
The fuel pump plungers are lubricated by the fuel itself

Governor

The hydromechanical governor is fitted to a gas turbine engine fuel pump to enable the engine to operate over a wide range of fuel specific gravities
The governor controls the maximum RPM of the engine by reducing the fuel pump stroke when maximum RPM is reached

Fuel Control Unit (FCU)

The FCU is trimmed to obtain maximum thrust output when desired
The FCU is adjusted to set idle RPM and maximum speed or EPR
Trimming is most accurate in no wind and low moisture conditions

Electronic Engine Control (EEC)

The EEC receives engine operating information and adjusts a standard hydromechanical fuel control unit to obtain the most effective engine operation
The EEC is a system that controls engine operation according to ambient temperature, pressure, and humidity

FADEC System

FADEC (Full Authority Digital Engine Control) system has electronic control of the hydro-mechanical fuel control unit in all modes
Active control switchover occurs on engine start-up only
Channel reset selects standby, which becomes active on the next start

Fuel Nozzle

The duplex fuel nozzle provides better atomization and uniform flow pattern
The flow divider in a turbine engine duplex fuel nozzle creates the primary and secondary fuel supplies
The valve on a vane type fuel flow measuring device becomes stuck, and a differential pressure bypass valve is the safety backup available for the engine fuel flow### Engine Fuel Shutoff Valve
Located downstream of the engine driven fuel pump

FADEC System

Consists of H.M.U, sensors, and an E.E.C
Primary purpose is to save fuel, reduce crew workload, and reduce maintenance costs
Receives primary power from a separate permanent magnet alternator
E.E.C measures pressure and temperature along with RPM
Can change digital inputs into analogue format to provide glass cockpit information and reduce flight crew workload
Has an automatic starting capability
Does not have automatic control of engine fire bottles

Throttle and Fuel Control

Throttle position is controlled by the crew or autothrottle
Fuel flow is controlled by the E.E.C in flight
Trimming is adjusting idle speed and maximum thrust
Fuel trimmer unit is adjusted automatically at altitude

FADEC Channels

Both channels are operating, but either one can be in command if they are both healthy
If a channel fails to receive information from a sensor, it will take the information from the other channel
If all air data input fails, the E.C.U reverts to an alternate (Fail-safe) mode

Engine Performance

Optimized performance is the reason FADEC was introduced
FADEC ensures efficiency is always maximum

Fuel System

Engine fuel pump has a wire mesh filter
Pressure drop across the Fuel Control Unit throttle orifice drops then increases due to increasing pump output
Fuel boost pumps are cooled using fuel
Main purpose of the fuel boost pumps is to provide fuel pressure to both engine pumps

Sensors and Valves

Silver strip on a fuel filter detects sulphur in fuel
Baffles in a rigid fuel tank prevent surge
End fittings on a fuel non-return valve are different sizes to prevent incorrect installation

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Assess your knowledge of swash plate pump operations, including flow direction, swash plate movement, and burner fuel flow. Test your understanding of these mechanical systems.