Engines Day 2 - Fuel pump and metering valve

Question 1

How many Stop-Electro-Valves per engine?

Answer 1

1 per engine

Question 2

What pumps are in the engine fuel system?

Answer 2

a Low Px pump and a High Px pump

Question 3

In normal operation, what is flowing through the starter injectors?

Answer 3

P3 air

Question 4

During the start, which pump is being used to purge the fuel system?

Answer 4

the Low Px pump

Question 5

What engine component is not installed on the engine?

Answer 5

the EECU

Question 6

What is installed to keep the system Px the same at all times?

Answer 6

a relief valve

Question 7

Which component has the relief valve in it?

Answer 7

the High Px pump

Question 8

The electro stop valve can be switch off by what means?

Answer 8

by the engine main switch being set into the OFF position, or automatically by the EECU if an engine overspeed is detected.

Question 9

What speed will trigger an OVERSPEED by the EECU

Answer 9

120% N2

Question 10

When will the Pressuring valve open?

Answer 10

When the Px reaches 52.2 PSI

Question 11

Where does the fuel travel to after the Pressurizing Valve?

Answer 11

to the centrifugal injector wheel

Question 12

A Level 1 pre-blockage in the filter will give what notification?

Answer 12

a white advisory

Question 13

A Level 2 pre-blockage in the filter will give what notification?

Answer 13

a yellow caution

Question 14

Can the engine be started with a level 1 pre-blockage message?

Answer 14

No

Question 15

What is required if a Level 1 pre-blockage message is illuminated?

Answer 15

maintenance

Question 16

What indication is there of a blocked fuel filter?

Answer 16

a mechanical pop-out

Question 17

Where is #1 engine EECU installed?

Answer 17

underneath the transmission deck

Question 18

Where is the #2 engine EECU installed?

Answer 18

in the R/H side shell

Question 19

What happens if N2 reaches 120%?

Answer 19

the EECU will automatically shut the stop electro valve causing a flameout.

Question 20

Where is the fuel valve assembly located?

Answer 20

on top of Module 3 (Gas generator)

Question 21

What type of pump is the Low Px pump?

Answer 21

a liquid-ring type pump

Question 22

What is the purpose of the venturi jet pump in the Low Px pump?

Answer 22

to improve the suction efficiency of the pump

Question 23

What type of pump is the High Px pump?

Answer 23

a Spur-Gear pump

Question 24

What is located inside the High Px pump?

Answer 24

a Px relief valve

Question 25

At what speed will the LP pump Px close the piston valve in the start purge valve?

Answer 25

40% N1

Question 26

How many microns is the fuel filter?

Answer 26

20 microns

Question 27

What Px will the filter bypass valve open?

Answer 27

15 bar

Question 28

How many Px transmitters are in each system?

Answer 28

2. One downstream of the filter, anf one Px & Temp upstream

Question 29

What does the constant delta Px valve do?

Answer 29

returns excessive fuel to the filter inlet to ensure tht fuel flow is only determined by the metering needle.

Question 30

What position is the meetering needle for engine start?

Answer 30

the “basic” fuel flow position.

Question 31

What speed will the start electro valve close?

Answer 31

61% N1 (self sustaining speed)

Question 32

Where are the starter injectors located?

Answer 32

2 o’clock & 10 o’clock of module 3

Question 33

a stuck open drain valve could cause what?

Answer 33

a loss in engine performance