I came across this comment from BOAC in an 18 month old thread.
Originally Posted by BOAC
- it was suggested to me (years ago) by a 'wise old head' that shutting down No1 when conditions permit might allow the LGTU to raise the gear.
This concerns the situation where you would have lost HYD Sytem A, consequently lowered the gear for landing and then having to divert. The general concensus is that the gear cannot be retracted without sys A. BOAC suggests that a 'wise old head' disagrees with this, I guess in order to reduce fuel burn and make it to a distant alternate.
To my surprise BOAC's posting was the final posting in this thread. Nobody bothered replying to this rather steep comment, strangly enough.
I guess you would shut down No1 and restart it as soon as the gear is up. You'll be in a lot of !!!!! if it wouldn't restart off course. Is it worth the risk? I guess if you only had one alternate airport and can't make it with gear down it is worth thinking about.
Is it technically possible to use the LGTU in this manner? I think it is, correct me if I'm wrong.
Has anybody done this, for real or in the sim?
Why wouldn't Boeing design it that way? The system to retract the gear with Sys.B is there, but it will only operate with "Eng. No1 RPM below a limit value". How hard is it to make a switch to operate the LGTU at will?
There must be a good reason for that I would think.
Can anybody shed some light?
Ziggy