Flying the 744 recently I had an ELEC AC BUS 3 failure. I tried to reset it without success. One of the results was the autothrottle disconnecting and I was unable to reengage it. The QRH refers to the A/T being inoperative if BUS 4 fails but BUS 3 is not mentioned specifically. Does anyone know if it is possible to reengage the A/T after a BUS 3 failure and if so how?

Flying the 744 recently I had an ELEC AC BUS 3 failure. I tried to reset it without success. One of the results was the autothrottle disconnecting and I was unable to reengage it. The QRH refers to the A/T being inoperative if BUS 4 fails but BUS 3 is not mentioned specifically. Does anyone know if it is possible to reengage the A/T after a BUS 3 failure and if so how?

Hi,The way I have always understood it is that any AC Bus failure will result in a loss of LNAV/VNAV, A/T, Ref N1 is blank (Dont recall ever seeing that?) However a loss of Bus 1 may 'also' result in unreliable Captains and standby instruments in Icing and a loss of Bus 4 will result in the same for the F/O this is due to the respective bus heating the probes for the capt & F/O LNAV/VNAV worked fine for me when I lost a Bus over the Pacific a long while back so I dont think any of this is simulated in the PMDG 744 except for loss of A/T RegardsRob