Engines Day 2 - Fuel pump and metering valve Flashcards
How many Stop-Electro-Valves per engine?
1 per engine
What pumps are in the engine fuel system?
a Low Px pump and a High Px pump
In normal operation, what is flowing through the starter injectors?
P3 air
During the start, which pump is being used to purge the fuel system?
the Low Px pump
What engine component is not installed on the engine?
the EECU
What is installed to keep the system Px the same at all times?
a relief valve
Which component has the relief valve in it?
the High Px pump
The electro stop valve can be switch off by what means?
by the engine main switch being set into the OFF position, or automatically by the EECU if an engine overspeed is detected.
What speed will trigger an OVERSPEED by the EECU
120% N2
When will the Pressuring valve open?
When the Px reaches 52.2 PSI
Where does the fuel travel to after the Pressurizing Valve?
to the centrifugal injector wheel
A Level 1 pre-blockage in the filter will give what notification?
a white advisory
A Level 2 pre-blockage in the filter will give what notification?
a yellow caution
Can the engine be started with a level 1 pre-blockage message?
No
What is required if a Level 1 pre-blockage message is illuminated?
maintenance
What indication is there of a blocked fuel filter?
a mechanical pop-out
Where is #1 engine EECU installed?
underneath the transmission deck
Where is the #2 engine EECU installed?
in the R/H side shell
What happens if N2 reaches 120%?
the EECU will automatically shut the stop electro valve causing a flameout.
Where is the fuel valve assembly located?
on top of Module 3 (Gas generator)
What type of pump is the Low Px pump?
a liquid-ring type pump
What is the purpose of the venturi jet pump in the Low Px pump?
to improve the suction efficiency of the pump
What type of pump is the High Px pump?
a Spur-Gear pump
What is located inside the High Px pump?
a Px relief valve
At what speed will the LP pump Px close the piston valve in the start purge valve?
40% N1
How many microns is the fuel filter?
20 microns
What Px will the filter bypass valve open?
15 bar
How many Px transmitters are in each system?
- One downstream of the filter, anf one Px & Temp upstream
What does the constant delta Px valve do?
returns excessive fuel to the filter inlet to ensure tht fuel flow is only determined by the metering needle.
What position is the meetering needle for engine start?
the “basic” fuel flow position.
What speed will the start electro valve close?
61% N1 (self sustaining speed)
Where are the starter injectors located?
2 o’clock & 10 o’clock of module 3
a stuck open drain valve could cause what?
a loss in engine performance
