Am I missing the point about these valves? They are only suppose to work and come into action as the A/C turns up side down(rolls over) after it has impacted with the ground. The two troopers were not strapped in because they never are just prior to disembarkation on OPs. As has been stated common practice known to all.
If I have read the reports correctly one was dead before the valves were required to operate and the other was going no where. If they had worked he would have needed evacuation and early medical treatment.
So the question is why did the A/C hit the ground in the first place. It seems to me that the Coroner has got the cause of the crash correct i.e. Pilot Error in a "Brown Out" was responsible for one death the second death could be debatable but with out the pilots actions in this case, the valves would not have been needed and the Pilots, Engineers, RAF, MOD would have all of happily flown on until the Puma was scrapped none the wiser or interested.
BobH