What is an RPDU? How many are there?
Remote Power Distribution Unit. 17
What amperage loads do the RPDU’s distribute?
10 amps or less
How many main 235Vac power system buses are there?
How are they designated?
4
L1, L2, R1, R2
How do the generators power the main AC buses with both engines online?
Each VFSG is connected to a main AC bus
How do the generators power the main AC buses with one engine running and the APU online?
VFSG’s power the on side main AC buses, ASG’s power the P150 Auxiliary power panel which provides power to the other side main AC buses through the tie bus.
How are the main AC buses powered with external power online?
External power connected directly to 115Vac buses. Main AC buses connected by the bus tie and powered by power converters from the 115Vac buses.
On the ground with only forward external power selected, what powers the 115Vac buses?
115Vac buses powered by external power directly.
What is the BPCU and what does it provide?
Bus Power Control Unit
- Overall load management.
- Electrical power transfers.
- Flight deck control and indications.
What power sources can the aircraft use for engine starts?
APU
2 Fwd external power sources
Other engine
Aft external power can only be used to assist a start for which engine?
The right engine
How many starters are needed to start the APU?
One
How many starters are needed to start an engine?
Two
Are both ASG’s required to maintain the electrical load in flight?
One or both depending on the load
What are the primary and backup power sources for the airplane brakes?
Primary: 28Vdc system
Backup: Main battery
On which side of the aircraft are the external power receptacles located?
2 on FWD left
1 on left aft side of the fuselage
How many external ground sources are required to energize the “Ground Handling Mode”?
One
In flight, when will the RAT automatically deploy?
- Both engines have failed
- All three hydraulic system pressures are low
- Loss of all electrical power to the captains flight instruments
- Loss of all four EMP’s and faults in the flight control system occur on approach
- Loss of all four EMP’s and an engine fails on takeoff or landing
Which cockpit displays are powered during RAT operations?
- Captain inboard DU
- Captain outboard DU
- Lower DU
- ISFD
What major systems are not available on “In-air RAT only mode, Standby Power)?
Flaps, Slats, Stabilizer trim, Packs, Thrust reversers, Auto speedbrakes, HUD, WIPS, (window heats, autothrottle, TAT, TAP, HF radios, SATCOM, TCAS, GPWS, XPDR, WX radar, external lighting, LNAV/VNAV, FMC predictions)
How is load shedding determined by the bus power control unit?
Loads are shed in order of priority to stay within the capacity of the available power sources.
What equipment is energized in the “In-air Battery only” mode (Standby Power)?
Captains flight instruments and other essential equipment for flight controls, navigation and communication.
- CPT and Lower DU’s
- ISFD, ECL, FMC (Limited)
- MCP, Autoflight & Autopilot (Limited)
- DSP L, MFK L, CCD L
- CPT/FO ACP & Interphone
- VHF L, TCP L, CCR L
- IRU, AHRU, INR, PFC
- ENG/APU fire detection
- Misc lighting
How can load shedding be monitored in the aircraft?
Electrical synoptic shows a list of systems affected by load shedding. Affected system synoptic (AIR, FUEL, HYD) also indicate equipment that is inhibited or shed.
What does the main battery power directly?
- Airplane power up
- Refueling
- Electric brakes
- CA flight instruments
- APU start assist
-Towing
What are the primary and backup power sources for the flight control computers?
Primary: 3 engine driven Permanent Magnet Generators (2 left eng, 1 right eng)
Backup: Airplane 28Vdc system, airplane battery and dedicated batteries.
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Airplane General31
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Limitations22
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Automatic Flight39
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Communications11
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Memory Items11
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Electrical System55
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APU23
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Air System57
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Fuel System34
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Landing Gear & Brakes27
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Hydraulic System20
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Engines (GE)39
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Fire Protection28
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Warning Systems36
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Anti-ice & Rain21
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Flight Controls79
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Navigation16
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Engines (RR)43
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Memory Items COPY11
