I can see why it might be hard to put hands on an original (and defective) PH PCU - 1.) they've all been replaced years ago, 2.) generally, defective FRU's are eventually binned or locked away (thanks legal department) but not after the factory has had a chance to examine them and the component parts for failure modes - allowing for an extraction of the weak link in the design or manufacturing process. Possibly the NTSB would have a couple of the accident/incident units still lying around.
We operated the classic for a few years before I came along. I'll see what our guys know about the PCU's disposition specific to our outfit.
Appreciate the response, not sure what you mean by Boeings initial findings.
I know it took them years, through several different investigations until they found the unit could jam or reverse. Off the top of my head I can't remember which incident it was, but I know if the primary slide jamed and the valve was subjected to thermal shock the secondary slide could jam or reverse. Is this the point you're referring to or have I missed something?
Precisely - you've nailed it in your 2nd paragraph, Barks!