Like the evidence that the a/c was not airworthy? (Despite the enormous number of people pushing that line.) What fault have they discovered?
Methinks you confuse serviceability with airworthiness. Nevertheless, a plethora of faults (and defects, if you know the difference) are noted in the AAIB statement and throughout Boscombe correspondence.
But the most significant fault in the context of achieving an overturn of the verdict is the Organisational Fault, as explained many times and ignored by those to whom it is an inconvenient fact. That was a contributory factor open to the Board of Inquiry (AP3207). If you want to place sole blame on anyone, it rather follows you must eliminate the possibility of any other factor; especially when the legal test is so high (beyond any doubt whatsoever). The RAF Chief Engineer and ACAS were sitting on a 373 page report in which every page spells out Organisational Fault, with page 1 listing Chinook losses attributed solely to systemic airworthiness failings. That single sentence should have been sufficient to cast doubt. Presumably the act of sitting on it and withholding it from those ultimately affected most, constitutes "elimination" in their book. Cover up, more like. At the very least there should have been mention of such a report with a reasoned explanation why it didn't apply. But there could be no such reason, so they (the RAF Establishment) had a choice. Do the honourable thing or blame the pilots.
I would be very surprised indeed if Lord Philip does not dwell at length on this report (CHART) and, hopefully, the underlying reasons behind the serious Organisational Faults it outlines. Not least, the fact that, like Haddon-Cave's report of 2009, it contains not a single word that came as any surprise; the majority having been notified in January 1988 following AMSO policies of the previous year that were having a so obviously detrimental effect on In Service aircraft. So serious is this issue, I can see it warranting further action, separate from the basic issue of clearing the pilots; both by Lord Philip and politicians.
Walter, you ask what has been discovered. That is not the point. It is what has been known all along but withheld that is the key issue here.