Originally Posted by
India Four Two
A question about manual trimming.
...
If the stabilizer is at the maximum nose-down postition, how many turns and how much time does it take to manually restore the stabilizer to a typical position for trimmed cruise flight?
50 rotations would be required to manually trim back to 5.0 units of trim from the full nose down position (0 units). Time to accomplish that would be dependent on the effort required.
The NG FCOM notes:
The effort required to manually rotate the stabilizer trim wheels may be higher under certain flight conditions.
The NG FCTM notes:
Excessive air loads on the stabilizer may require effort by both pilots to correct mis-trim. In extreme cases it may be necessary to aerodynamically relieve the airloads to allow manual trimming.
With full nose down trim and full nose up elevator at 300 knots at 5000 feet you'd expect that there would be a significant air load on the stabiliser.