Engines/APU

Question 1

What does the Autothrottle limit (AT LIM) indication mean?

Answer 1

The FMC is not providing the A/T system with N1 limit values, The A/T is using a degraded N1 thrust limit from the related EEC.

Question 2

When do the EGT start limit redlines display?

Answer 2

Until the engine achieves stabilised idle (Roughly 59% N2) for ground starts and some in-flight starts.

Question 3

During T/O or G/A exceeding the MCT limit won’t cause the EGT to change to amber for how long?

Answer 3

5 Minutes.

Question 4

When does “ENG FAIL” appear on the EGT gauge?

Answer 4

Engine operating below sustainable idle (Less than 50% N2) and engine start lever in the idle position.

Question 5

Does the “LOW OIL PRESSURE” Alert illuminate when oil is at or below the red line or the amber line?

Answer 5

At or below the red line.

Question 6

“START VALVE OPEN” “LOW OIL PRESSURE” “OIL FILTER BYPASS” have a blinking function before displaying - What is this?

Answer 6

They blink for 10 seconds before they display solid
blinking is inhibited when:
- During T/O from 80kts to 400’ RA or 30 seconds after reaching 80 - Whichever comes first
- During landing below 200’ RA until 30 seconds after touchdown.
- During these periods alerts still illuminate but solid.

Question 7

When is the LOW oil pressure amber band displayed?

Answer 7

Above 65% N2 and then above this is variable depending on the N2% rpm.

Question 8

Do the ignitors activate when the starter are in off?

Answer 8

Yes!
- If an uncommanded rapid decrease in N2 occurs
- N2 is between 57% and 50%
- In flight - N2 is between idle and 5%

Question 9

With the “ENGINE CONTROL” lights illuminated the engine control system is not dispatchable, when does the light operate?

Answer 9

Engine is operating and aircraft on the ground below 80kts or approximately 30 seconds after touchdown.

Question 10

How long is reverse thrust blocked at reverse idle position?

Answer 10

Until reverse thrust reverser is more than 60% deployed.

Question 11

What are the primary engine indications?

Answer 11

N1 and EGT

Question 12

When the EEC is not powered, what indications are displayed directly from the engine sensors?

Answer 12

N1 / N2 / Oil Quantity and Engine vibration.
- During a battery start with no power to the aircraft only N1/N2 and oil quantity are available.

Question 13

When does the EEC become powered?

Answer 13

When the engine accelerates to a speed greater than 15% N2

Question 14

Does a loss of either DEU affect the EEC’s?

Answer 14

Yes - It results in a loss of signal to both EEC’s and they revert to alternate mode to prevent the engine operating from a single source of data.

Question 15

Does thew EEC provide N1 and N2 provide redline overspeed protection in alternate mode?

Answer 15

Yes provided in both normal and alternate modes.

Question 16

When does Approach Idle come on?

Answer 16

Engine anti ice is on for either Engine 1 or 2 or
Altitude below 19,000’ + any main gear is down and locked or
Altitude below 19,000’ and flaps are 15 or more.
If fault prevents EEC from receiving flap or gear position then Approach idle will initiate below 19,000’

Question 17

What is starter CUTOUT speed?

Answer 17

Approx 56% N2

Question 18

If a Wet start occurs (EGT no rise after Start lever is moved to idle) when does the EEC turn off ignition and shut off fuel to the engine?

Answer 18

15 Seconds after the start lever is moved to Idle?

Question 19

Are start protections available in flight starting?

Answer 19

No, only on the ground - The EGT start limit redline can be shown depending on the start logic.

Question 20

Can the thrust reverser be deployed in flight?

Answer 20

Yes - When either RA senses less than 10’ RA

Question 21

Can the APU power both packs in flight?

Answer 21

No - Both on the ground or one in flight - It will also shed Galley and Main busses in the air.

Question 22

Where does the APU get its fuel?

Answer 22

Left side of the fuel manifold when the AC fuel pumps are operating, If they are not operating fuel is suction fed from the No. 1 tank.

Question 23

Where does electrical power to start the APU come from?

Answer 23

No.1 Transfer bus or the main battery.

Question 24

How does the battery switch affect the APU?

Answer 24

Moving the Battery switch to OFF automatically shuts down the APU because of loss of the APU ECU.

Question 25

How long can the APU start cycle last?

Answer 25

120 seconds.

Question 26

How long does the shutdown process for the APU take?

Answer 26

60 seconds.

Question 27

What powers the left ignitor plug?

Answer 27

AC transfer bus 1

Question 28

What powers the right ignitor plug?

Answer 28

AC standby bus

Question 29

Will the master caution light illuminate if the engine enters the soft ALTN mode?

Answer 29

Yes

Question 30

At what point do the EGT start limit redlines disappear?

Answer 30

Stabilised idle (Approx 59% N2)

Question 31

When does ENG FAIL illuminate?

Answer 31

When engine is operating below sustainable idle it displays on the EGT gauge

Question 32

How is fuel heated before entering the engine?

Answer 32

Two fuel/oil heat exchangers where IDG oil and Engine oil heat it.

Question 33

During an impending Hot Start, the white box surrounding the EGT flashes white until when?

Answer 33

It resets when start lever is moved to CUTOFF or the engine reaches Idle N2

Question 34

Can both busses be powered by the APU in flight?

Answer 34

Yes!

Question 35

During APU start cycle, how hot can the APU EGT get?

Answer 35

Up to 1100 degrees.

Question 36

How long should the APU be operated for before use as a bleed air source?

Answer 36

2 minutes