I think there maybe a slight confusion in this thread. I believe the accumulators that were mentioned in the first post by Sprocket refer to the ones which ensure the hydraulic system provides continuing control assistance during extreme flight manouevres which could otherwise cause a hydraulic servo to lock up momentarily (sometimes known as jack stall) due to the inability of the hydraulic fluid pump to provide sufficient flow at times of high demand. A hydraulic jack locking up during an extreme manouevre could cause loss of control until such time as the pump managed to catch up (which may be too late to recover the aircraft to a safe attitude).
These accumulators are not intended to provide hydraulic pressure for extended periods following a pump failure or other system failure. In this event, the aircraft must have an alternative back up (or parallel) system which can allow the pilot to retain control functions. In the case of smaller helicopters with acceptable control forces, the pilot may have to do all the work him/herself following a hydraulic system failure.
I believe that earlier models of the Dauphin without accumulators had a warning light which warned the pilot of incipient jack stall. This would normally occur when the pilot demanded high roll rates at the same time as a rapid pitch change. As I have limited experience on the Dauphin, maybe someone with more knowledge of the type could correct me.
Last edited by coalface; 8th September 2002 at 11:23.