Engine System Flashcards
What part of the engine drives the external gearbox?
The HP shaft.
What does the engine external gearbox drive?
No. 1 and No.2 hydraulic systems. Main AC Generator. Combined LP and HP fuel pump. Oil Pump. Generator for the HP compressor and RPM tachometer. The EEC generator.
What is the normal ground idle value?
About 53% NH
What is the normal flight idle value?
56.2% NH
What busbar does the engine ignition system get its electrical power from?
The 28V DC ESB.
How many stages does the LP compressor have?
2 stages.
How many stages does the HP compressor have?
5 stages.
How many turbines are there?
2: the LP and HP turbines, each are single stage.
Where is the engine bleed valve located?
In the HP compressor case.
Why does the engine have a bleed valve?
To relieve pressure to prevent HP compressor from stalling during engine start.
What value of NH does the engine bleed valve close at during start?
Approx. 51% (2% below ground idle).
How many oil return scavenge pumps are there?
3
How is the engine oil cooled?
Using a Fuel Cooled Oil Cooler (FCOC).
How many magnetic chip detectors does the engine oil system have?
3
Where are the engine oil magnetic chip detectors located?
In the return lines (back to the reservoir).
When is the 10 second delay applied to the OIL caption (i.e. oil px warning)?
Why is this the case?
When the gear is locked up.
To prevent nuisance transient warnings.
What is used to cool the EEC circuits?
A small recirculation flow of fuel.
State the fuel flow chain between the LP fuel pump and the fuel manifold.
LP Fuel Pump FCOC LP Fuel Pump Filter HP Fuel Pump FMU/ FMV Fuel Manifold.
How is the EEC powered?
Engine below 40%NH: Powered by 28V ESB.
Engine above 40%NH: Powered by a dedicated engine driven generator.
How long are the igniters activated for when:
1) Relight button pressed on the ground (WoW).
2) FADEC/ EEC activates igniters (in automatic response to a surge).
3) Relight button pressed when airborne.
1) For as long as the button is held.
2) 15 seconds.
3) 30 seconds/ until throttle advanced past idle.
State the auto-surge-recovery process controlled by the FADEC/ EEC.
Surge detected.
Igniters energised (15s).
Waits 0.5s (to allow it to self clear).
Observes for a further 1s to see if stall/ surge occurring.
If surge detected, SRG caption illuminated for 5s (+surge audio).
EEC dips amount of fuel to engine to clear surge.
GET THIS CHECKED
Up to what NH does the air starter motor provide assistance?
45%
What happens if the air starter does not start to turn within 5 seconds of engine start being demanded?
APSCU terminates start and APU is shut down.
What does air from the air starter turn?
The engine HP compressor.
What caption will be illuminated if the bleed valve solenoid fails?
What other clues are there that the bleed valve is not closed after start?
EEC
T6 about 50 degrees C higher than usual.
RPM slightly lower than usual.
What checks are automatically carried out after engine stabilises at ground idle following a start?
Overspeed governor check.
MFC test.
How long after Weight Off Wheels does the APU shut down if left on before T/O?
10 seconds.
What is the maximum T6 during an engine relight?
840 degrees C.
What is the maximum (sustained) NH rating?
104%
What is the Maximum (sustained) T6 rating?
880 degrees C
What is the maximum T6 during engine start?
637 degrees C.
What is the maximum transient NH and T6?
104.5% and 885 degrees.
Whilst in MFC, what is the minimum NH that should be sustained if possible?
70%.
What is the maximum tailwind for a ground start?
15kts.
What is the minimum fuel drain time after an aborted engine start?
2 minutes.
What is the maximum number of failed starts permitted before the aircraft is declared U/S.
3.
What is the APU starter cooling time? (i.e. minimum time between APU attempted starts).
3 minutes.
What is the maximum height and speed for starting the APU when airborne?
20,000ft AMSL and 380kts.
Is APU operation under negative g permitted?
No.
When ambient air temp is below 5 degrees, what is the maximum running time for the APU?
5 minutes.
Above what RPM will the EMP flash?
110%
Above what RPM will the EMP occult?
120%
Below what RPM will the EMP occult?
10%
What T6 should you expect after start?
About 350 degrees C.
What does it mean if SRG caption remains on for more than 5.5 Seconds?
FADEC unlikely to recover from surge automatically.
What temperature will cause the Jet Pipe thermocouple to trip, activating a JPOHT caption?
How many detector switches are there?
150 degrees C.
There are 4 detector switches.
Above what engine NH will the clutch between the air starter motor and the engine not engage if air starter motor used during a relight.
20%
What triggers an OIL caption?
When is a time delay on this caption enforced, and how long is it? Why is it there?
When the difference in the oil pressure of the internal gearbox feed and the return oil pressure is too great.
When the gear is locked up. 10 seconds.
To prevent transient warnings.
What triggers an FPR caption?
When the differential pressure across the LP filter is too low.
What triggers a T6NL caption?
If T6, NL or NH exceeds their limits.
Within how many seconds of selecting Start (or APU coming online) should the IGN caption be displayed?
15 seconds.
Within how many seconds of the IGN caption being displayed and the throttle being moved to Idle should the engine light?
15 seconds.
Within approximately how many seconds of selecting Idle on start should the RPM stabilize at 53%?
30 seconds.
How many thermostatic detector switches are there in the Jet Pipe Bay?
4
Above what temperature do the thermostatic detectors in the jet pipe bay activate?
150 degrees C
Above what T6 does the EMP flash?
1000 degrees C.
Above what T6 does the EMP occult?
1027 degrees C.
