Can't engage after "STANDBY POWER OFF" failure?

[fjsharry 0]

During trip fly in Greenland,i got "STANDBY POWER OFF" failures,i saw some situation 1.IRS(L) turn to ON DC. 2.FMC(L) power off by itself. 3.AP can't engage! Then i usd QR handbook advice,open STANDBY POWER cap turn to BAT,and i turn IRS and FMC two switch to both on R,waiting a while result is LNAV can open,but Autopilot can't open? Does i miss something??And even i fix all failure in FMC,AP still can not engage!

[Spin737 102]

You've got the A/P on according to the pictures. (Note the CMD indication) You don't have a roll mode selected, however.My QRH may differ from yours, but mine says STBY POWER SWITCH----BAT. It doesn't say anything about the other items you did.

[dverha 0]

If I'm right the autopilot does need both IRS' to be operational. If one of the two fails you have to revert to manual flying. But I don't have the FCOM available at the moment so I'm not sure.Kind regards,Daniel Verhaal

[ARM505 0]

I just did this in the sim - lightning strike, followed by standby bus fail. It was in the B734 sim, but I think the NG is roughly the same - you won't be able to use the A/P. It's quite a crappy failure actually.

[fjsharry 0]

You've got the A/P on according to the pictures. (Note the CMD indication) You don't have a roll mode selected, however.My QRH may differ from yours, but mine says STBY POWER SWITCH----BAT. It doesn't say anything about the other items you did.

I just did this in the sim - lightning strike, followed by standby bus fail. It was in the B734 sim, but I think the NG is roughly the same - you won't be able to use the A/P. It's quite a crappy failure actually.

@Matt This picture was take before turn STANDBY POWER OFF to bat.@Simon As you say this failures is serious problem? So if got this failures,i need find airport to land.I will take some time to practice this situation.

[xxJohnxx 21]

Why did your plane started to burn?

[fjsharry 0]

If I'm right the autopilot does need both IRS' to be operational. If one of the two fails you have to revert to manual flying. But I don't have the FCOM available at the moment so I'm not sure.Kind regards,Daniel Verhaal

Burn?I try this failures procedure again,get few different result,first AP can work after turn STANDBY POWER OFF to BAT,i don't know why AP can't work in last time. And LNAV & VNAV both can open after turn to BAT. But TCAS and left side ADF VOR FMC not work after turn BAT.@Daniel You are right,autopilot need both IRS to work.