Originally Posted by
RetiredF4
I remeber only those, where the trim beforehand wound all the way NU and ceased in the full NU position. If you refer to those, then it would have been better beforehand that the trim stayed in normal trim region.
Yes, but it didn't, because (in the cases that come to mind) something else was broken.
It would have been better if the broken thing wasn't broken, but it was. Thereafter the loss of autotrim, coupled with lack of crew re-trim, caused deaths. Having got to that situation, it would have been better if autotrim had stayed engaged so that the trim did not impede the recovery.
If ceasing of trimming action in ALT1 is not a bad thing, i cannot follow the argument, why it would be bad in ALT 2.
What trim values are reached in normal operation except takeoff and landing?
Is Full NU a player above FL100 in any kind of normal maneuvering? In which one?
In Alt1 there is data available (known-good) that is not available in Alt2. Acting on known-good data is not a bad thing. Acting on known-bad data is.
As to what trim values are normally used, I don't know - but I doubt the designers put the mechanical end-stops where they are without reason. If no more than, say, 9deg nose up was
ever needed, then the stop would have been at 9deg not 13.