Originally Posted by
RVDT
Shy take a look at how the thing works. It was not the input that failed but lets say the "output" to cancel the input via the feedback mechanism.
It's pretty simple - when all 3 points attached to the lever line up with the servo valve in the neutral position nothing happens as the control shaft moves and cancels the input request.
As the feed back end became detached - nothing to cancel the input - servo motors to the stop and in this case full right pedal?
BTW - Sikorsky has been fitting centreing as the result of accidents or incidents not unlike this one - not pro-actively.
The design and acceptance of the AW models may be under review shortly. If not I will be very surprised.
Yes, I have done. If you can be bothered to read back my previous posts on this topic (they date back some 17 years), you will see that I don't disagree with you.The servo ran away to full travel because the servo valve remained open; there was nothing to centralise it once a common part became detached. The common factor / weak point in this design is that the pilot control inputs route via the same lever that nulls the servo; unfortunately that's what came adrift because a single nut disconnected. On other designs, this isn't the case.
BTW - Sikorsky has been fitting centreing as the result of accidents or incidents not unlike this one - not pro-actively.
But surely the purpose of airworthiness legislation is to ensure that everyone designing aircraft learns from past history; irrespective of which type first had an accident....