Gidday Deadhead.
My question specifically excluded "common knowledge/sense", it was purely intended to raise the point that it is likely no-one has been specifically trained not to move the said levers out of said position under said circumstances at all.
It's impossible to offer you an answer without
including common sense (as opposed to common knowledge). In my experience over the years I've never observed a trainee or expeienced pilot select the mixture from idle cutoff back into the operating range either unintentionally
or intentionally (piston engine). The decision (and intent) is to stop the engine so there is no logical reason why you would want to do it (move it from idle cutoff).
Although the condition levers on the Dash carry out several functions (including fuel shutoff), one could still draw a common thread between its function, and that of the mixture lever on a piston engine (purely speaking in terms of them being the primary control of fuel for startup/shutdown).
It's like turning the key off in your car - Why would you switch it back on once you've decided to turn it off? I know it's being over simplistic, but it's illogical (
apologies to Mr. Spock).
I'm aware of a number of incidents involving the
inadvertant selection of fuel off and back to start feather.
All were as a result of
accidently moving the condition lever through the shutoff detent (ie there was never the intention of shutting down the engine - only feathering), then realising the error, and quickly moving it back to start/feather. This typically has occured during an abnormal situation such as an ECU malfunction (PW120). I know of nobody who has
ever intentionally selected fuel off, then back on in the Dash.
My opinion is that the design of the detents
could be better. As for the training aspect, I think there was paperwork issued stating that in the event of an
inadvertant selection to fuel off, the condition lever/s should just be left there.
And that leads me to the next question: using your terminology, what constitutes a "stopped" engine? If it is when all rotating parts have stopped rotating, how do we determine this? By instruments? Some turbines I flew (eg Garrett) had RPM gauges so small you couldn't tell when it hit the zero stop, and in others they lost electrical power late in the shutdown sequence so you didn't know! So you had to assume that after a few minutes had elapsed, you could be assured that, indeed, the engines were "shut down".
Yes, I've got a little time on Garretts, too. Being a fixed shaft engine, generally if I looked out the window and the prop wasn't turning, I assumed the internal rotating components were also not rotating.
The run down time of the PW12x varies, but the NH gauges are reasonably accurate. When I wrote "stopped", I meant NH reads zero (FWIW). Limitations for start are in our engineering manual. The correct handling techniques of the condition levers are taught at type endorsement level in our company.
