Electrics/Fire/Warnings Flashcards
What does each AC power system consist of? (4)
- XFR BUS
- Main Bus
- 2 Galley Buses
- Ground Service Bus
What power do the AC generators supply?
3 phase 115V 400Hz AC power.
Why will an IDG automatically disconnect?
High oil temperature.
Can also be disconnected manually in the cockpit.
Why will SOURCE OFF illuminate inflight?
When respective XFR BUS is powered through BTB system.
What is overload protection of the AC system?
Incrementally sheds loads when on single IDG.
In what order is AC load shed?
First galley and main bus power on XFR BUS 2. Then XFR BUS 1. If continues, next is the IFE.
Will auto restore if another GEN comes online.
What will automatically be load shed inflight if APU GEN sole source?
All Galley and Main Buses, if still overloaded, IFE.
Where can APU attempt a full electric load?
On ground.
When will the DC Cross Tie Relay open during normal operations? (2)
- When GS captured by either AP or FD.
- BUS XFR switch to OFF
What switch will OPEN DC Cross Tie Relay?
Bus XFR switch in OFF position. (Normally in AUTO)
When is TRANSFER BUS OFF illuminated?
When respective XFR BUS not powered.
When will STANDBY POWER OFF illuminate? (3)
Loss of power to either AC Standby Bus, DC Standby Bus or Battery Bus.
What does the Standby Power switch in AUTO allow?
Allows automatic transfer of power to standby buses whether aircraft inflight or on ground.
What is the AC Standby Bus powered by in normal conditions?
Transfer Bus 1
What is the DC Standby Bus powered by in normal operations?
TR1+2, using TR3 as a backup.
In case of AC power failure, what is the AC Standby Bus powered by?
Inverter from the battery. Same as DC STBY BUS.
What does the battery remove power from when placed to off?
BATT BUS and Switched HOT BATT BUS when operating normally.
What does BATT switch on power?
Switched Hot Battery Bus, and energises relays to provide automatic switching of standby electrical system when normal power fails.
When may the BATT DISCHARGE light illuminate in normal operations?
APU Start
What does the TR UNIT light illuminate for?
Whenever a TR unit fails on the ground. Inflight, monitors TR1 and a combined TR2+3 failure.
What causes the ELEC light to illuminate?
On ground whenever there’s a DC Power System fault or Standby System fault. Inhibited inflight.
What will the DRIVE light illuminate for?
Low IDG oil pressure.
When will the DRIVE light illuminate? (3)
- Engine fail
- IDG Fail
- IDG disconnect
When are the IDG disconnect switches operational? (2)
Electrical power available and engine running.
When will the automatic engine generator online function work? (3)
- APU power fails
- APU turned off
- Switch to IDG on takeoff
Where is the DC power usually powered from?
28V DC from the TR’s.
No direct control over DC system.
What is powered by TR1?
DC BUS 1 and DC STBY BUS. Can be all 3 TR’s if cross tie relay closed.
What can be powered by all TR’s of cross tie relay closed?
DC BUS 1, DC STBY BUS and DC BUS 2.
What TR is BATT BUS powered by?
TR3, with an alternate source from the battery charger/battery.
How can the standby system be powered when the BATT switch off?
Standby power switch must be placed to battery to power standby system from battery.
How many TR’s are capable to supply total connected load?
2
What the main and aux batteries, and how long will they last?
24V NiCad batteries. Provide standby power for minimum 60 minutes.
What indicates if engine overheat detected, or APU DET INOP?
Master Caution
What will fault monitoring fire system do if it senses a fault?
Deselect bad loop. Then only selected loop (A or B) can activate warning.
What does overheat FAULT light indicate?
Both loops are malfunctioning.
What happens when the APU fire switch is pulled up? (3)
- Arms squibs
- Close APU Fuel SOV
- Trips generator field and generator breaker.
Is there a fault warning for wheel well fire detector?
No. Detector only checked by use of OVHT/FIRE TEST switch.
Nose wheel well has no fire detection capability.
Where is the APU ground control panel?
Right aft main wheel well.
What happens if ground control APU fire handle pulled down? (4)
- APU Fuel SOV
- Bleed air closes
- Inlet closed
- Trips APU GEN & Generator breaker.
Is there a light to show APU bottle has been discharged?
No. Only discharged from cockpit.