Originally Posted by
Bergerie1
I cannot remember or find the details, but there were some incidents back in the early days of the 707 when airloads did backdrive the screw jack on the stabiliser. BOAC had one over Toronto shortly after take-off and the crew only just managed to retain control. Some posters on PPRuNe may be able to find or, perhaps, know the details.
There have been a number of 707/720 accidents where the THS has been implicated, including a fractured jackscrew, a stalled actuator and a trim motor failure, but I'm not aware of any that involved a working stabilizer jackscrew being backdriven by airloads.