Mr. Sky,
Originally Posted by
sky9
Doppler Data.
1 If power is off an aircraft on the ground does the aircraft ACARS ping when power is turned on or does it wait until INMARSAT interrogates it?
Power up sequence would have SATCOM waking up and sending an initiating "I'm here" logon message. This is also true in the case of a temporary loss and subsequent recovery of the Left Main AC bus.
2 I'm not familiar with the T7, but flew the 763. Does the apu autostart if there is a complete loss of electrical power on the busses.
It does upon loss of both AC transfer busses.
3What's the location of the fuel feed for the APU in relation to the Engine feed. Is it likely that that APU would find fuel other than in the fuel line if the engine feeding from that tank shuts down due to fuel starvation.
According to our guy in coveralls, the DC APU pump suction port is located within a few yards of the aft main AC boost pump inlet. The DC APU pump housing is located in the center tank, but the inlet is in the left main tank. If there is pressure on the left engine fuel manifold, the DC pump does not run and the left main boost pumps are the source(s) of fuel pressure for the APU.
4 If there is a total AC electrical failure the aircraft will have battery power. What bus is the ACARS receiver powered from? In other words when a 777 is on 30mins (?) of battery power is the ACARS still functioning in its basic mode?
There is no dedicated ACARS "receiver", however the VHF radios provide a primary means of communication and are powered by DC busses. ACARS is an integrated sub-function of the dual AIMS, which is also DC powered. (I covered this function earlier.) Provided there is no DC bus fault, the AIMS, Comms radios, and ACARS would be up and running despite a loss of AC power. Naturally, any data inputs from equipment that relies on AC power would go quiet.
Total loss of AC power would be a very unusual event on this aircraft, barring fuel starvation. There are a total of 5 high-capacity AC generators on the aircraft, 4 engine mounted and one 120kva unit in the APU.