Boeing 767 Center Electrical System Questions
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Boeing 767 Center Electrical System Questions
Hello,
I understand the center electrical system exists for autoland redundancy but am struggling to find much information about it in the FCOM.
As far as the equipment that's on the center electrical system (2 buses I presume, 1 AC and 1 DC?) I have only found the following items listed:
Center autopilot, Center ILS, Center Radio Altimeter.
I suspect that the center symbol generator, center FCC, and center IRU would also normally be powered by the center electrical system, as they should also be isolated during autoland, but am speculating as I have no reference for this.
So, the center system is normally powered by the left AC and DC buses, however the center system exists for autoland redundancy. Whenever the "approach mode" is armed, relays transfer the center buses from Left AC/DC sources to the Hot Battery Bus (which in turn is being powered by the Battery Charger through the ground service bus). One of my references says that the Standby AC bus also provides power to the center system during autoland.
My main questions, I guess, are what other equipment besides Center ILS, Center Autopilot, and Center Radio Altimeter is powered by the center electrical system? Doesn't the connection to the Standby AC bus during autoland contradict it's independent redundancy since the AC Stby bus is powered by the Left AC bus during autoland, or does the AC standby bus relay switch from Left AC power to Inverter?
Thank you.
I understand the center electrical system exists for autoland redundancy but am struggling to find much information about it in the FCOM.
As far as the equipment that's on the center electrical system (2 buses I presume, 1 AC and 1 DC?) I have only found the following items listed:
Center autopilot, Center ILS, Center Radio Altimeter.
I suspect that the center symbol generator, center FCC, and center IRU would also normally be powered by the center electrical system, as they should also be isolated during autoland, but am speculating as I have no reference for this.
So, the center system is normally powered by the left AC and DC buses, however the center system exists for autoland redundancy. Whenever the "approach mode" is armed, relays transfer the center buses from Left AC/DC sources to the Hot Battery Bus (which in turn is being powered by the Battery Charger through the ground service bus). One of my references says that the Standby AC bus also provides power to the center system during autoland.
My main questions, I guess, are what other equipment besides Center ILS, Center Autopilot, and Center Radio Altimeter is powered by the center electrical system? Doesn't the connection to the Standby AC bus during autoland contradict it's independent redundancy since the AC Stby bus is powered by the Left AC bus during autoland, or does the AC standby bus relay switch from Left AC power to Inverter?
Thank you.
Last edited by RandomPerson8008; 15th Nov 2015 at 01:21.
Random,
An interesting question/scenario. You are sort of on the right track as far as power supply to the Centre System is concerned. Indeed in normal ops the Centre System is powered from the Left Main AC and DC buses respectively.
However during triple channel autoland ops the Standby System is the independent power source for the Centre System and supplies power to the Centre DC Bus directly from the Hot Battery Bus (via the battery charger) and the Centre AC Bus is supplied from the Standby Inverter.
However, as for what is supplied/powered from the Centre System, I can only suggest getting your hands on a maintenance manual/avionic engineer. Hope this helps.
McHale.
An interesting question/scenario. You are sort of on the right track as far as power supply to the Centre System is concerned. Indeed in normal ops the Centre System is powered from the Left Main AC and DC buses respectively.
However during triple channel autoland ops the Standby System is the independent power source for the Centre System and supplies power to the Centre DC Bus directly from the Hot Battery Bus (via the battery charger) and the Centre AC Bus is supplied from the Standby Inverter.
However, as for what is supplied/powered from the Centre System, I can only suggest getting your hands on a maintenance manual/avionic engineer. Hope this helps.
McHale.
