41 Questions
What component of the fuel pump gives an initial pressure increase and pumps fuel to the gear elements?
Impeller
Why are shear sections incorporated into the drive system of each gear element?
To allow for independent operation if one element fails
What is the purpose of the check valves in the fuel pump system?
To prevent recirculation through the inoperative element
Why is one element of the duplex spur gear pump capable of supplying sufficient fuel for most engine demands?
It has a larger capacity
What happens to excess fuel not required by the engine in the fuel pump system?
It is recirculated to the inlet side of the gear elements
Which component allows for the recirculation of excess fuel in the fuel pump system?
Relief valve
In the duplex spur gear pump assembly, how many gear elements are present?
Two
What role does the relief valve play in the fuel pump system?
To relieve excess pressure from the system
What happens to the inlet ram air pressure and mass airflow when an aircraft increases in speed or descends?
Increase
In governed operation, when the engine speed is set and not changed, what variables can affect the engine's operation?
Altitude and airspeed
What senses the changes in inlet air pressure and mass airflow during aircraft speed or altitude changes?
Inlet and burner pressure bellows
During descent or slowing down, what happens to the inlet air pressure and mass airflow?
Decrease
What is the role of the multiplying lever during governed operation of the engine?
Maintain the air/fuel mixture ratio
How does the engine react to changes in aircraft speed or altitude during steady operation?
Adjust air/fuel mixture automatically
What is set at a certain position and not changed during governed operation of the engine?
Engine speed
Which component of the engine moves in response to changes in inlet air pressure and mass airflow?
Multiplying lever
What does the spring located in the downstream side of the control piston do?
Maintains a pressure differential of 100 PSI
How does the control piston act upon the ball valve?
Modifies its action
What happens to the pressure differential across the throttle as inlet pressure decreases?
It decreases
During engine start, what does the pump servo piston spring do?
Moves the pump cam-plate to full deflection
Where does fuel flow during engine start, passing through the throttle valve?
To the FCU
What is the initial position of the throttle at rest?
Fully retarded
What does the spring do when the control piston senses no differential pressure?
Closes the spill valve
What does the supervisory electronic engine control system do?
Limits fuel flow based on TGT, N1, and N2 compressor speeds
Which signals does the control amplifier receive in the system?
Turbine gas temperature (TGT) and two compressor speed signals (N1 and N2)
How does the pressure regulator function in this system?
Regulates fuel pressure at the fuel pump
At what point does the electronic circuit start to function as a fuel limiting device in this system?
Near full power
What happens when predetermined TGT and compressor speed values are reached in this system?
The pressure regulator reduces fuel flow to the spray nozzles
Which signals does the fuel flow regulator receive in this control system?
High speed compressor (N3), gas path pressure (P1, P2, P4), and power lever position
How does the fuel flow regulator adjust fuel flow in this system?
Based on signals from high speed compressor, gas path pressure, and power lever position
What does the electronic circuit start to function as when near full power is reached?
A fuel limiting device
Where is the fuel flow transmitter typically located?
In the fuel manifold, just upstream of the fuel nozzles
What does a fuel flow transmitter measure?
Amount of fuel consumed by an engine per hour
What can higher than normal fuel consumption in one engine compared to another indicate?
Underperforming engine
Which type of transmitter is shown in Figure 30?
Rotating vane transmitter
What does the vane in the rotating vane transmitter carry at one end?
Ring-type magnet
What type of output signal does the fuel flow transmitter produce?
Electrical signal
Why are fuel flow transmitters used in multi-engine aircraft?
For engine troubleshooting and condition monitoring
What does a higher than normal fuel consumption for a given power setting suggest?
'Under-performing engine' warning may be appropriate
Which part of the fuel flow transmitter forms a magnetic coupling with the electrical transmitting unit?
'Ring-type magnet'
What kind of device is a fuel flow transmitter?
Electro-mechanical
Test your knowledge on the configuration and operation of a spur gear pump used in aerospace applications. Learn about how fuel enters the pump at the impeller and gets pumped to the gear elements for discharge.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
