sprag clutch issue
I have no idea if this is related to the accident, but thought I'd mention it anyway.
I attended a Kaman technical briefing at Heliexpo this year, and a significant part of the briefing centered on issues with the Kmax sprag clutch.
Part of that discussion centered on pilot behavior, to the effect that clutch "overruns" were being frequently experienced in the field, due to pilots allowing the rotor to overspeed during descents with a load. Apparently due to the nature of the design, the rotors tend to overspeed fairly easily during faster descents with heavy loads.
Kmax reported that these clutch "overruns" were occuring several times a day in some cases, causing premature wear of the sprag clutch. This wear is turn could lead to a clutch "slip" event, where the clutch could slip under power.
Kaman released a new "box" called an "Aural Warning System" designed to monitor these clutch problems, and released a service bulletin for their installation in the Kmax fleet. It consists of a box with an aural warning system, an "overrun" counter and a "slip" counter. There was mention of clutch inspection intervals at certain counts, and other clutch inspection details were included in the bulletin. I recall that a certain number of "overruns" were allowed before a clutch inspection, but only a single "slip" event was needed to trigger an immediate clutch inspection.
The very idea that a "slip" event could occur under power, sent shudders down my spine. It was also mentioned that a newly redesigned sprag clutch would be ready for service in 2004.
I mention this issue in relation to this accident, because of the remote possibility that violent torquing events could be applied to the rotors, if a sprag clutch suffered an on-off-on "slip" event under power, causing rapid on-off applications of torque to the rotors. It's very odd indeed for a helo to shed all of its rotor blades at once, and I thought this might be a possibility.