That service bulletin was obviously written by the manufacturer, who has a vested interest in making sure that jack stall is deemed a universal issue for all helicopters, for obvious, legal, reasons. Otherwise, those who were harmed as a result of this design shortfall would have recourse for damages.
The statement in the service bulletin that says "You should understand that servo transparency is a natural phenomenon for any flyable helicopter" is patently untrue. I have significant experience testing several helicopters to be sure that they cannot and do not experience any control feedback where the controls lock up, become "transparent" or stall because of maneuvering. In fact, NO military helicopter is allowed to have this problem, it is specifically tested for in the structural flight testing. I would enjoy seeing the data that the FAA used to back up this erroneous assertion.
Last edited by NickLappos; 18th February 2008 at 19:40.