John,
Seems I recall having the Speed Trims extended at least than 60 knots or so put severe stress on the Aft Vertical Shaft. In theory it would have made for a much higher nose high attitude while hovering for sure.
For those "not knowing of Chinooks"....each rotor head has an electrically operated....airspeed controlled system called Speed Trims that operate to level the airframe at high airspeeds and reduce drag. Each head has an electrically powered actuator that provides some forward tilt to the head based upon an airspeed input. The system operates automatically and has switches in the cockpit to allow for manual operation if required or as a means to retract the Speed Trims if they fail in the extended position. If the aft actuator remains extended at low speed or a hover....a lot of stress is applied to the Aft Vertical Shaft that extends from the Aft Transmission to the Aft Rotor Head.
Last edited by SASless; 17th Jul 2012 at 22:39.