@ EFP058: It's a hydro-mechanical friction locking device. It uses blue system hydraulic pressure (same as flaps, nosewheel steering, spoilers) to lock and unlock. It will only engage if the following conditions are met: Blue sys press 2900 PSI or above, gust lock engaged, a/c on ground and condition lever (fuel/propeller control) no. 2 in feather OR fuel shut off.
As for ground crew working around the engine - well, it can TECHNICALLY be treated as an APU, but as all things devised by the human mind it can fail. So except from connecting/disconnecting the GPU, no work will be performed on the righthand side while in H-mode.
On a curious note, the FCOM allows refueling with the engine in H-mode
Again, the difference btw what's legal and what's smart...
Subsonic, you don't use GPU? On most airports where you fly regularily, you should be able to negotiate a handling contract where, say, first 30 min GPU use is included in basic handling fee. This will save a lot of wear on the battery + the engine. Plus it will allow pax to deplane without either having to listen to eng. 2 running or boarding with only MIN CAB LT
Brgds,
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