GTS MOD2 Fuel Pump Operation at Low RPM - DEFENCE AEROSKILLS TRAINING ACADEMY

Play an AI-generated podcast conversation about this lesson

What happens to the paralleling valve when the engine reaches 16% RPM?

It opens the path of fuel flow between the secondary and primary pump elements.

It increases the RPM to 65%.

It switches off the fuel pump.

It closes the path of fuel flow between the secondary and primary pump elements. (correct)

Why does the fuel pump go into parallel mode during engine starting?

To maximize fuel pump volume. (correct)

To restrict fuel flow.

To reduce engine RPM.

To minimize fuel pump volume.

What happens when the back pressure is felt due to the closed paralleling valve?

The centrifugal boost pump stops working.

The primary pump check valve opens.

The high pressure fuel filter opens up.

The secondary pump check valve closes. (correct)

At what pressure does the secondary pump pressure switch close?

150 PSI Signup and view all the answers

Why does a cockpit light illuminate when the secondary pump pressure switch closes?

To indicate that the pump is in parallel mode. Signup and view all the answers

What is the purpose of the low pressure fuel filter in the fuel flow path?

To remove impurities from the fuel. Signup and view all the answers

Why does each element have a separate fuel flow path in parallel mode?

To maximize fuel pump volume. Signup and view all the answers

What initiates the closure of the paralleling valve?

Engine reaching 16% RPM Signup and view all the answers

What happens when the engine speed governor reacts to speed variations?

Moves the roller cage against the multiplying linkage Signup and view all the answers

What is the role of the pilot servo valve rod in governing engine speed?

Affects roller cage position through the multiplying linkage Signup and view all the answers

How does the spring cap react during acceleration when the power lever is moved upwards?

Slides down the pilot servo valve rod and compresses the flyweight speeder spring Signup and view all the answers

What function does the pilot servo valve serve in controlling air/fuel ratio changes?

Slows the movement of the pilot servo control rod Signup and view all the answers

When the pilot valve rod moves downwards, what happens to the roller?

Moves down the incline plane and to the left Signup and view all the answers

What is the purpose of compressing the flyweight speeder spring during acceleration?

Forcing the flyweights to an under-speed condition Signup and view all the answers

How does the roller cage position affect engine operation?

It returns the engine to a steady governed state Signup and view all the answers

Which component helps prevent sudden air/fuel ratio changes in engine operation?

The pilot servo valve Signup and view all the answers

What differentiates the variable displacement pump from the constant displacement gear type pump?

The variable displacement pump changes pump displacement to meet varying fuel flow requirements without changing speed. Signup and view all the answers

How is the pumping action produced in a variable displacement pump?

By moving the rotor to impart a reciprocating motion to the plungers. Signup and view all the answers

How is the action of a variable displacement pump infinitely varied?

By altering the inclination of a cam-plate to change the length of plunger stroke. Signup and view all the answers

What causes variations in the movement of the servo piston in a variable displacement pump?

Variations in pressure difference across the servo piston. Signup and view all the answers

How does a fuel control unit regulate pump pressure and delivery in a variable displacement pump?

Automatically and accurately when integrated with a variable flow pump. Signup and view all the answers

What is mechanically linked to the cam-plate in a variable displacement pump?

Servo piston Signup and view all the answers

What is biased by springs to give full stroke position of the plungers in a variable displacement pump?

Servo piston Signup and view all the answers

What effect does varying fuel servo pressure have on a servo piston in a variable displacement pump?

Causes corresponding variations in cam-plate angle. Signup and view all the answers

What happens to the burner pressure as the engine slows down?

It decreases Signup and view all the answers

What does the multiplying linkage and roller mechanism do in response to the decrease in burner pressure?

Moves further to the right Signup and view all the answers

What happens when the new flyweight force reaches equilibrium with the speeder spring force?

The flyweights return toward an upright position Signup and view all the answers

What is the purpose of allowing the engine to stabilize at idle before shutdown?

To enable gradual turbine cooling Signup and view all the answers

Why is it essential to follow a shutdown procedure on a simplified fuel control unit?

To prevent overheating of the engine Signup and view all the answers

What is the role of the fuel shut-off valve during the shutdown process?

It remains closed Signup and view all the answers

How do the flyweights position themselves after responding to a speed change?

Return toward an upright position Signup and view all the answers

Why does burner pressure decrease as the engine slows down?

To decrease fuel flow Signup and view all the answers

What does a supervisory electronic engine control system do?

Receive information from various engine sources and limit fuel flow Signup and view all the answers

Which signals does the control amplifier in the system receive?

Turbine gas temperature (TGT) and two compressor speed signals (N1 and N2) Signup and view all the answers

At what point does the electronic circuit in the control system start to function as a fuel limiting device?

Near full power Signup and view all the answers

How does the pressure regulator in the installation regulate fuel flow?

By reducing fuel flow to the spray nozzles Signup and view all the answers

Which signals does the fuel flow regulator in the system receive?

N3 compressor speed, gas path pressure, and power lever position Signup and view all the answers

What role does the control amplifier play in the system?

Receives signals from turbine gas temperature and compressor speeds Signup and view all the answers

When does the pressure regulator reduce fuel flow to the spray nozzles?

When predetermined TGT and compressor speed values are reached Signup and view all the answers

What triggers the electronic circuit to act as a fuel limiting device?

Near full power, predetermined TGT, and compressor speed values being reached Signup and view all the answers