To: Arm out the window
Back in the mid 1950s Sikorsky engineers tried to develop a system that used stored energy in a spring to force the collective down in the event of engine oil pressure loss. There was one major problem in that in order to cock the spring they used a hydraulic piston with the spring inside of the cylinder. The pressure was generated from the transmission driven hydraulic pump, which started to turn when the transmission started to turn. As speed built up the pressure was sufficient to cock the spring but in order to do that, the collective would have to rise due to the extension of the cylinder. This would increase pitch to the maximum but the blades were not turning fast enough so they would stall out due to inadequate lift and would hit the tail cone. The system fault was discovered by yours truly and I brought it to the attention of the hydraulics engineer who had no background in flight controls theory or aerodynamics. Two days later the test rig was removed and several days after that the engineer was let go.