Hi Mr Purdey,
May I start by saying that I don't believe that there are any uncertainties about the fact that the aircraft continued towards the hills when the rules of airmanship said that the crew should not do so. Aircraft should not hit the ground - I agree.
What my whole argument is about is that there may be mitigating circumstances why the accident occurred. There may have been an actual mechanical failure or control jam or there may have been an assumed emergency. It is because of these elements of doubt that the burden of proof for absolutely no doubt whatsoever is undermined. I hope the following information explains this particular paragraph.
Picking up on Tandemrotor's accurate description of ZD576, I invite you to look at the service history from the point of return to the UK after Mid-Life Update:
8 Apr 94 - Returned from Boeing. Experiences a FADEC problem.
21 Apr 94 - During a transition to hover the helicopter has a torque mismatch of 40%. No engine warning lights illuminate. Number one engine is replaced. (Cause was a faulty torquementer).
26 Apr 94 - Has a problem with engine control levers at the flight idle position. There was no torque indication to either engine and the number one engine ran high. Whole engine replaced again.
3 May 94 - GPS failed to operate.
5 May 94 - GPS failed to operate.
9 May 94 - No GPS feed to RNS252.
10 May 94 - A large spring detached from the collective lever. It was found that the bonding had failed to keep the spring in place. The engineering note stated that there was cause for concern with regards loose atricles within the flying control closet.
17 May 94 - Engine power warning light illuminates three times. Engine temperature also goes beyond its normal level. As a result, part of the FADEC system is returned to the USA for investigation. The engine is stripped and rebuilt.
18 May 94 - Number one ECU PTIT rises (undemanded) to transient 950 degrees C for about 1 second before returning to normal temperature. The ECU is changed.
20 May 94 - During control checks, an unusual vibration was felt when raising the collective. Loose washers and securing nut were found on the CPT assembly. No locking wire was found.
26 May 94- During flight, numerous warning lights illuminate, including the master warning light and a number two engine failure notification. The helicopter makes an emergency diversion to a civilian airport.
31 May 94 - ZD576 delivered to RAF Aldergrove. The IR jammer has a fault. It is replaced.
1 Jun 94 - During flight, there is a problem with the PTIT guage. It is replaced upon landing.
2 Jun 94 - The PTIT guage plays up again and later in the the task it is noticed that there are problems with the RNS 252. However, on return to Aldergrove the faults could not be replicated.
The crash occurs later that day during the second sortie.
As you can see, not an inspirational aircraft.
The Board's comments with regards to the Chinook HC2 in RAF Service concluded, "Nevertheless, an unforseen technical malfunction of the type being experienced on the Chinook HC2, which would not necessarily have left any physical evidence, remained a possibility, and could not be discounted ".
The Board go on to say "In considering the available technical information the Board concluded that technical failure was unlikely to have been the direct cause of the accident. However, given the large number of unexplained technical occurrences on the Chinook HC2 since its introduction, the Board considered it possible that a technical malfunction or indication could have proved a distraction to the crew ".
Taking into account the impeccable history of ZD576, could you say with absolute certainty, that nothing occurred to distract/prevent the crew from making the turn after they deliberately changed the waypoint reference? I, and many others - including the Board of Inquiry, don't feel able to.
My apologies for such a long reply, but I hope it explaines my viewpoint sufficiently.
Finally, to follow on from Tandemrotor's post again, I'm happy to meet anyone to bore them to death on this subject - travelling distance considering! (Oh, if only Messrs Hoon & Blair would be willing!)
My best, as always.
Brian
"Justice has no expiry date" - John Cook