6: Electrical

Question 1

Auto generator on-line when?

Answer 1

Takeoff with:
Apu powering both transfer busses
Apu is shut down or fails

Question 2

Automatic load shedding (engine generators)
NB, for single generator operation

Answer 2

1. Galleys and main bus on transfer bus two
   if an overload is still sensed
2. Galleys and main bus on transfer bus one
   if an overload is still sensed
3. IFE buses

Question 3

Automatic load shedding (second generator restored)

Answer 3

1. IFE/PASS busses auto restore
2. Restoration of galley and main bus restored by switching CAB/UTIL off then back on

Question 4

What happens if you intercept ILS with a TR unit light?

Answer 4

The cross bus tie relay (DC bus tie relay) opens. The related DC bus is then unpowered which scatters the flight deck with multiple instrument flags and amber lights

Question 5

PSEU light

Answer 5

Obviously just on the NG
On ground:
* a fault is detected in the PSEU
* an overwing exit flight lock fails to unlock when commanded

In-flight: inhibited from thrust lever advance for T/O until 30s after landing

Question 6

MAINT light

Answer 6

Obviously only on the MAX
A fault exists
Inhibited from first engine start until 30s after landing

Question 7

TRANSFER BUS OFF

Answer 7

related​ transfer bus is not powered

Question 8

Loss of Transfer bus 1, what are the big things you will lose? (6)

Answer 8

1. Isol valve inop- affects wing anti-ice
2. Pitot and probe heat inop- avoid icing conditions
3. Left wing anti-ice valve stuck in last position- to turn off you have to turn eng 1 bleed off
4. App mode not advisable because TR1 not powered
5. Standby power OFF should not illuminate
6. Engine no 1 Left ignition inop- select both

Question 9

Loss of transfer bus 2, what are the big things you will lose? (11)

Answer 9

1. Pressurization panel lcd inop
2. Pitot heat- avoid icing conditions
3. Autopilot B inop and autopilot A inop after 5 min
4. Weather radar inop
5. Main bat charger inop- BAT DISCHARGE
6. Eng no 2 left ignition inop- select ignition both
7. Flap position indicator inop- use the bottom of the upper red bar tape
8. TE flap alternate motor inop
9. Stab, rudder and aileron trim inop. Do the stab trim inop NNC- F15 landing
10. IRS fault- do NNC
11. App mode not advisable
    12.