This isn't intended as an argument for one side, and against another, but I'd appreciate it if somebody more knowledgeable would correct where I'm wrong regarding airworthiness - my 'understanding' is as follows:
1) The RAF considers an aircraft airworthy provided the risks associated with operating it are reduced to ALARP.
2) The RAF asked Quinetic to report on the MR2, and were told there were 30 items to fix to make MR2 ALARP.
3) Out of those 30 items a few are contested - the RAF believes the Nimrod will be ALARP without them being fixed. I can understand this might in fact be so, although I think they ought to explain why this is so if they want to reduce the criticism level.
4) Some items are no longer requiring a fix, as they relate to AAR which is now cancelled - a procedural fix, again I can see how this is okay.
5) 21 (was it?) items have been agreed by the RAF as requiring a fix, but the fixes haven't been done yet - until these are fixed presumably Nimrod MR2 isn't ALARP?
In light of (1) and (5) how can the RAF describe the aircraft as anything other than non-airworthy? This isn't a rant, it's a genuine question - I'm not after opinions about whether it's safe, or needed in theatre here, I'm simply asking which bits I misunderstood because as I read it the aircraft is non-airworthy according to the RAF's own criteria... is (1) true or not, and is (5) true or not? If 1 and 5 are in fact correct, then the aircraft isn't airworthy. (For what it's worth I'd like it to be okay, I just don't see how anyone can say it is).
Pipe testing - I'm not an engineer, here comes the almighty 'but'....BUT I'd have thought the way to test for a leak in any systrem was to pressurise it and monitor the pressure - if the pressure drops you have a leak. Whether you use a liquid or a gas to pressurise it in any given circumstance I'll leave to wiser heads, although I suspect a gas would be better. (Gases tend to escape from confinement more readily than liquids).
Not wishing to offend any engineers with this, but a pressure drop will guarantee (provided temperature isn't changing) that the gas is escaping somewhere. (PV over T Kelvin is constant and all that).
Dave