PAC Report
Ex Grunt
I would certainly support the PAC statement - if you want the airworthiness issues in detail please find time to read the engineering critique on the BoI (see link above to pulse1) where you will find full details to back up their opinion. Sadly the PAC has already made such a strong statement before, but with no obvious effect on MOD's position. Still it is nice to see that they still believe it and that by saying so they again reject the Gross Negligence verdict.
Twin Act
I assume that such things as uncommanded engine run-ups etc have been fixed, but a current operator needs to confirm this. However it took some time as more than a year after the Mull accident the US Army Release to Service for their "new" Chinook still contained warnings on DECU connector security and false FADEC fault codes etc.
In October 2003 I attempted to encapsulate my enginnering investigation into a single A4 page - as shown below. This was given to Hoon at a meeting with senior members of the Mull Group and was rejected, unread, as "no new evidence". This is one of the reasons why I hope that PPRuNe contributors can change direction from considering some of the very low chance operational reasons to what I consider (but like everybody else I still do NOT KNOW) to be the very high chance that a technical issue, possibly only a transient one, was a direct and major contributor to the accident.
UNUSED AND NEW EVIDENCE RELATING TO THE AIRWORTHINESS OF CHINOOK HC2 ZD 576
In making its early decision to “eliminate as possible causes: major technical malfunction or structural failure of the aircraft prior to impact” and to focus “on the crew’s handling and operation of the aircraft” the BoI, including the Review process not only ignored taking potentially significant evidence but also failed to follow up evidence showing potential airworthiness, engineering and maintenance issues that was placed before it. As such, either by direction or of its own volition, the BoI behaved in a partial manner and the findings were heavily biased in favour of a verdict that ensured that the RAF themselves were not questioned on their decisions and shortfalls in their processes. The finding of a balance of probabilities of aircrew error, changed to Gross Negligence by the Senior Reviewing Officer, could not have been justified if the available evidence had been correctly analysed and followed up. Such actions would have shown that the airworthiness status of the Chinook HC2 fleet at that time, potentially coupled with a major technical defect on ZD 576 itself, was a plausible alternative cause for the accident.
JSP 318 (Regulation of Ministry of Defence Aircraft) defines “Airworthiness” as “the ability of an aircraft or other airborne equipment or system to operate without significant hazard to aircrew, groundcrew, passengers (where relevant) or to the general public over which the airborne systems are flown”.
The Airworthiness Chain
The BoI Terms of reference do not specifically task the Board to look at whether the aircraft was “airworthy” in terms of MOD’s own definition of airworthiness, despite the fact that the “problems” of the Chinook HC2 fleet at that time were well known to supervisors and commanders. However the Board is specifically tasked to assess the equivalent “Human Failings”. The Board, including the Reviewing Officers, does not mention “airworthiness” at any point.
Witness 20 ably sums up the fleet airworthiness problems of the Chinook HC2 with his evidence: The unforeseen malfunctions on the Chinook HC2 of a flight critical nature have mainly been associated with the engine system FADEC. They have resulted in undemanded engine shutdown, engine run-up, spurious engine failure captions and misleading and confusing cockpit indications.” In their findings the BoI use this evidence but omit the words “flight critical nature”. ZD 576 had experienced all of these problems in the short period since its acceptance off the conversion programme. No confirmation of the cause of these defects had been established when it was decided to transfer the aircraft to the Aldergrove detachment. In addition to these “accepted” engine problems ZD 576 had suffered a major control problem leading to the need for fleet checks and a serious defect report – the results of which were still outstanding at the time of the accident.
To justify its action in ignoring engine problems or a control malfunction as potential causes of the accident the BoI “interprets" AAIB evidence in a way that the much more experienced AAIB inspector does not support. The latest Boeing simulation analysis shows that a control malfunction cannot be ruled out and that the engine power settings would have to have been at full or emergency power – in direct conflict with the BoI/MOD cruise/climb theory.
The links in the airworthiness chain include maintenance standards. The BoI found clear evidence of a major lapse of maintenance standards at Aldergrove, but takes no action to follow this up. Key witnesses such as OC Engineering Wing RAF Odiham who would have been responsible for the airworthiness of ZD 576 and for the engineering standards of the Aldergrove detachment (which was still operating to the Odiham EOB) were not called at all.
The Board does ascertain (witness 4) that the Senior Engineering Officer 230 Squadron and not the Chinook Detachment Commander, was responsible for the engineering supervision of the attached Chinook aircraft and personnel. However, despite the clear lapse in this supervision, no attempt is made to find out how this responsibility was being discharged, how such a major breach of engineering regulations was ignored and most importantly how, as the front line link in the airworthiness chain, he was “satisfied that Chinook HC2 ZD576 was serviceable for it’s (sic) final flight on 2 Jun 94”.
Summary
In summary, the Board, including the Review process, does not consider the central question of whether, either as a result of the Release to Service process and/or the defect history of the aircraft, the “airworthiness chain” was still intact for ZD 576. There is clear, and unused, evidence that it was not, and that there is at least one more plausible explanation for the accident. It is also clear that the RAF’s decision to operate the HC2 at all with the introduction to service problems it had at the time, as well as the choice of the HC2, and ZD 576 in particular, for a high profile but non-operational, passenger flight could be called into question.
Again please check the link to the engineering report for a fuller picture.