Sir Peter
Thank you for your faith in me (!) but it’s not my trade, so can’t even comment on the fuel pressure issue. I would just repeat observations made before.
It is quite common for MoD to introduce design changes by Service Engineered Mod. The original justification process underpinning SEMs has long since been overtaken by one factor – quick and cheap. But often in the rush for cheapness, proper testing and trials are ignored and maintainers are not provided with the wherewithal to verify any repairs to the mod. It is long standing policy not to buy spares to support aircraft mods and, as test equipment and tech pubs are dealt with at the same time via the same process, they often suffer a swell. This scenario will be instantly recognisable to any maintainer here, and the abuse of the SEM system is a major standing risk. (The same applies to UORs). They have their place.
Also noted elsewhere is cable chaffing being a common ignition source. When considering this in conjunction with tolerance build-up, maintainers will again know that the relative position of same cables/looms between tail numbers can vary enormously. From what I know of the Nimrod, with the mainplanes being essentially handmade and no two being identical, this tolerance build-up may be significant. I have also seen major defence contractors make the howler no 1st year apprentice should make – insert negative tolerances in cable/loom drawings. (Not suggesting this is the cause, just illustrating a point). This is a very difficult area to manage and record under the Configuration Control process. I know other aircraft where dimensional differences between production runs are known, and recorded as call-ups in the GA. This info is used to, where necessary and as far as possible, ensure no materiel is manufactured which cannot be fitted; but it’s not always possible. This of course is insignificant compared to MoD’s long standing practice of denying funding to routinely maintain configuration control, which breaches their own airworthiness regulations. This kind of contradiction disturbs me.
I mentioned this the other day, in response to Bingo Handjob. Did anyone read the report by the Select Committee on Public Accounts? CDP was asked to confirm Configuration Control would be maintained on a specific aircraft. (A very good leading question, and one should ask what prompted it. My guess is Mull of Kintyre). He said yes. What wasn’t said was that the same CDP also ruled that a project manager could be formally disciplined for refusing to proceed to contract when no provision was included for Configuration Control, or other components of airworthiness. OK, it was a few years ago, but various Ministers of State have consistently upheld his ruling. And been kind enough to confirm it under FoI. Now, that’s something that really disturbs me.