I think I'm replying to some 2 year old postings, but wrt:
"Exemption No. 9589, dated January 28, 2008, to § 27.695. This exemption was granted to permit a powered flight control system without considering the
jamming of a control valve as a possible single failure."
Several people responded about how it was no big deal to fly with the boost off, but that's not really the point, is it? What about a hard-over on one of the servos? Especially in a 2 bladed system, how bad is it to suddenly have a servo go full travel without warning?
Granted, I much prefer having the boost off switch on the cyclic as compared to having to let go of the collective in the Bell, but I still worry whether I'm strong enough to prevent mast bumping while my thumb is going for the switch.
Can anyone comment on what it's like to have a servo go hardover on any kind of a helicopter? I've asked a knowledgeable person about how often accidents are caused by these kinds of problems and all he said was that it has occurred (and that he had been involved in at least one investigation of such a failure but I'm not sure he was referring to a helicopter).
I'd also be curious to hear from test pilot sorts (Nick?) whether this is something that is testing during certification?