Lots of interesting answers, thanks, guys.
VnV...
"Certainly the autostart logic has a minimum N3 for starting threshold and a max motoring detector based on the rate of change of N3,..."
I apologize. I just realized you answered a similar question I had about Autostart logic a few years ago (I guess I must have had brain fade).
You said (regarding Autostart) ....
" the N3dot threshold is 0.275 %/sec and strictly the IP shaft (N2) has a variable threshold for fuel on between 7 and 10 %, depends on oil temperature and also a max. motoring restraint too, determined in the same way as N3."
Regarding this.... Are you saying that the N3 or N2 can be lower as long as they've reached max motoring? (How about both being lower? Are there absolute no-go rpms even though both rotors are max motoring?).
I ask because we had a failed Autostart recently... and for the CMC message generated, the Fault Isolation Manual simply said that the engine failed to meet the start requirements. Less than 10kts tailwind was mentioned in the logbook, but we would also liked to have known things like how many engines were being started at the time, was there a pack on and what was the bleed pressure at the time. Of course, the flight crew cannot be expected to look at and report all these things.
Thanks.
Cheers.
Q.