In relation to some of the immediately foregoing, it may help to divide the arguments into 2 areas:
1. Would RAF Engineering personel release an aircraft to fly that did not comply with published limitations and maintenance directives, or use their common sense to consider an accumulation of fuel leakage issues against the whole picture?
I would be shocked if the answer to this was "Yes". I don't know the limits, the tanks etc, but I'm sure those directly involved were satisfied that the aircraft as it was, was within limits. Within the bounds of their knowledge, the aircraft (ie in terms of specific airframes) would therefore be considered "airworthy".
2. Does the aircraft meet the regulatory standard as required in JSP 553?
If it is shown that the aircraft (ie the Nimrod as a fleet) doesn't meet that, and the designer and customer knew this, and knew what could be done to improve the situation and did not address the issues, then that is a different matter entirely. The guys directly involved in maintaining the aircraft wouldn't know that they were dealing with a problem beyond their influence.
Going back to cars for a moment, if you have a car that appears perfect, but has an inherent flaw, what visibility of this do you the owner or the garage that services it have visibility of the problem? As an example, have a search for info on Ford and the Pinto car fuel tank. One article on the matter is here:
http://www.autosafety.org/article.php?did=522&scid=8
In the case of XV230, and sitting on the sidelines, I'd be looking more at answers to the second question rather than the first question.
The BOI should address both, and, to ally TD's concerns about membership of the BOI having no crash investigation experience I'd advise not geting hung up on that. It is the nature of the composition of a BOI. They aren't there to be expert accident investigators - there aren't enough people in the RAF on each type, or enough accidents (thank goodness) to generate expertise. To get the full picture (or as full a picture as possible without access to the aircraft) the BOI will have sought expert advice form a range of organisations. Been there, done that, so would discourage harassment of the BOI.
sw