Question 484

  Sqn Ldr Morgan was clear in his evidence. The day after the Mull accident the lead test pilot at Boscombe Down phoned him to make it clear that the grounding of their Chinook the day before was in no way connected with the accident, and that the problems they were having were connected with icing trials.

  Boscombe Down took the decision not to authorise further flying trials whilst further information was awaited. Air Cdre Crawford (retd), the Commanding Officer at RAF Odiham at the time, will be giving evidence on 7 November and the Committee may wish to put this issue to him.

Question 489

  Lord Tombs asked Sqn Ldr Morgan whether he was aware of the detached control pallets in the broom cupboard at that time. However following the Mull crash it was most of the inserts that are bonded into the control panel that were found to have become detached, not the control pallets themselves. Lord Tombs had the opportunity to examine the control pallets in a broom cupboard of a Chinook MkII, and discuss them with RAF and civilian engineers, when he visited RAF Odiham on 22 October. We trust this allayed his concerns.

Question 502

  Lord Hooson inquired about the time taken for pilots to get used to the new systems on the Chinook MkII, asking whether Flt Lts Cook and Tapper had only been on this helicopter on two or three occasions. In reply Sqn Ldr Morgan spoke of the transition course from the MkI to MkII which both pilots had completed and the check flight that each pilot was given which was undertaken by the pilot who delivered ZD576 to RAF Aldergrove. The two pilots had of course also successfully completed routine in-Province tasking in Chinook ZD576 from 9.45am until 15.20 on the day of the crash and Flt Lt Tapper signed to say that he accepted the helicopter was airworthy before taking off for the early evening flight to Fort George.

Question 556

  Lord Jauncey asked whether the small metal particles which the Air Accidents Investigation Branch found in the residual fluid in parts of the boost actuator might have had some effect at the time of the accident.

  Fine metal slivers were found on one of the servo screens of the yaw Integrated Lower Control Actuator, but these are filters which are designed and positioned in the hydraulic system specifically to capture debris of this type and to provide protection for its operation and integrity. The Air Accidents Investigation Branch report concluded that these did not appear to have been associated with the effects of the accident and that there were no indications to suggest that they had contributed to it.

  The Fuels and Lubricants Department DRA Woolwich analysed a fluid sample from each system and found them to be consistent with used OM-15 reportedly the normal type for RAF service, that would normally be considered fit for further use.

Question 567

  Lord Jauncey raised the issue of the E5 code which was recorded at the Wilmington incident and also in the DECU of Chinook ZD576 after the accident.

  The E5 fault code which was found in the memory of the DECU of RAF Chinook ZD576 indicated that a soft fault had occurred at some point over the life of the DECU since delivery. However, a "soft fault" cannot affect the safe operation of the control system and is therefore one that has no impact on the normal control of the aircraft.

  The rotational speed (N2) of each engine's Power Turbine Spool is detected by two sensors. The E5 code would be displayed either because of a power interrupt (switching from the Auxiliary Power Unit to main generators, or the reverse) or if a discrepancy of 5 per cent or more is detected between the two N2 signals. When such a discrepancy is detected the lower N2 signal is disregarded (or locked out). If the other signal is then lost, the original locked-out signal will be re-acquired. Should both signals be lost, the fuel to the engines will be maintained at the pre-failure rate.

  The "E5" fault on the pre-production software that caused the Wilmington incident was significant as the system at that time operated differently. The team undertaking the test at Wilmington did not appreciate the significance of the E5 signal, which was displayed due to the discrepancy of 5 per cent or more between the two N2 signals, causing the lowest signal to be latched. The team then removed a connector which resulted in the loss of the only remaining N2 signal. With the one signal latched, and the loss of the remaining N2 signal, unlike the system now, the pre-production software did not re-acquire the original locked-out signal. Instead the DECU "saw" an N2 value of zero, and in order to restore the N2, the system provided more fuel to increase the speed of the power turbine. This caused the rotors to accelerate and seriously damaged the aircraft.

  After the Wilmington incident the software was amended, hence a similar incident could not have caused the Mull of Kintyre accident. The Air Accidents Investigation Board's report of their technical investigation into the accident found no evidence of a technical malfunction that could have contributed to the accident, with the possible exception of a radar altimeter system fault.

Question 570

  Captain Kohn spoke of an incident involving an American Chinook where there was an electrical malfunction which was traced to water having ingressed through the flight deck windows. The problem of water ingress and its potential effect on an aircraft's electrical system is well known to the RAF, and the Board of Inquiry into the Mull accident specifically considered whether an electrical failure was a possible cause of the accident. The technical investigation found that both Automatic Flight Control System Computers had been powered at the time of the accident and that major pre-impact loss of electrical supplies had not occurred.

Question 590

  Captain Hadlow said that he considered that the position in which the rudder was found by the Air Accidents Investigation Branch (a 77 degree left pedal 1.7 inches forward) was a last ditch effort to turn the aircraft.

  Small yaw pedal inputs are used with cyclic to maintain balanced flight when performing a turn at low speeds but at higher forward speeds little or no yaw input is required to turn the aircraft. But large yaw pedal inputs are made, with cyclic and collective, during "hover" turns and when also performing "fast stops". This technique uses all the flying control inputs to turn the aircraft into a sideways position whilst in forward flight, in order to use its large surface area to act as an air brake and assist in the rapid reduction of speed.

  As you are aware, after considering all the evidence, the RAF Board of Inquiry concluded it was most likely that, approaching the Mull, the aircraft was established in a steady climb, with an airspeed of about 150 knots, until approximately four seconds before impact. At that point, the only profile consistent with the impact parameters and component conditions was a cyclic flare to 30 degrees nose up. These controls inputs would be entirely commensurate with the pilots suddenly becoming aware of their proximity to the ground.

  The Board of Inquiry concluded that the displacement of the yaw pedal might well have been caused by the force of the impact, a point which Witness A said should not be ignored (see his response to question 807).

Question 799/800

  While he was responding to Lord Jauncey's question as to when the pilots would normally have been expected to alter course, Witness A made the comment that the crew would have been completely within their rights to be flying at 50ft over the sea with the tips of the rotors no more than 30ft away from the cliffs, but immediately qualified this saying that this would not have been good airmanship.

  We strongly endorse the last statement. There was no need for the aircraft to have been flown so close to the cliffs, this was a routine transit flight, not an operational flight. The pilots had been entrusted with the care and safety of 25 passengers, and their comfort and safe passage should have been uppermost in the crews' minds. The pilots should not have taken any risks.

Questions 826-829

  Witness A raised the matter of the transponder settings found in the wreckage of ZD576. These were "0000" and "7760" and Witness A pointed out that the emergency setting is "7700".

  The normal responder codes for a Visual Flight Rules flight would be "0000" and "7000". "7760" is a meaningless code and it is most likely that the settings were disturbed by the impact with the Mull.

2 November 2001

Evidence of Sqn Ldr Robert Burke

Question 659 and Question 755 et seq: Alleged Exclusion from Accident Investigation and Board of Inquiry Process

  Sqn Ldr Burke stated he was given a direct order form Wg Cdr Cooke, his immediate superior at that time, allegedly on instructions from above, that he was not to continue to help in this investigation in any way. He was not to discuss the crash with anyone, nor to approach anyone, nor to give any information relating to this crash to anyone. We contacted Wg Cdr Cooke who vehemently denied Sqn Ldr Burke's statement. Wg Cdr Cooke has now submitted written confirmation of his recollection of events. His statement is attached. Further, Wg Cdr Cooke's superior officer, the then Gp Capt Peter Crawford the Station Commander, has also countered Sqn Ldr Burke's allegations. He will address this most important point in his evidence to the Committee on 7 November.

  Turning to Sqn Ldr Burke's non selection for the Board of Inquiry team, the simple fact was that the Group Staffs, who selected all the Board members, determined that Sqn Ldr Gilday was the most appropriate officer for this task. Sqn Ldr Burke was a maintenance test pilot and had not flown on operations for many years. Sqn Ldr Gilday was responsible for the supervision of Station Operations, and had flown helicopters for at least 4090 hours, including 529 hours on Chinooks (details of hours flying while on courses are not to hand). He had also previously acquitted himself well in assisting a Board of Inquiry, and this would have been useful experience.

Question 655: Two Run-up Incidents at Boeing in Philadelphia

  Sqn Ldr Burke mentioned that he had experienced two run-ups on the ground when flying with an American army test pilot. The Department has records showing that in December 1993 when Sqn Ldr Burke was at Boeing in Philadelphia, an engine on Chinook ZA714 experienced a 5 per cent power increase. This had occurred on the ground during reversionary beep testing and was not caused by a FADEC software failure. The US handling test pilot has expressed the view that this incident may have been inadvertently triggered by Sqn Ldr Burke, who apparently leaned on the beep switch, which commanded the engine to increase speed.

  Sqn Ldr Burke also mentioned a second incident that occurred when he was flying at Boeing with a civilian test pilot, saying that he reported this incident, when the aircraft froze or experienced a run-down, to the Department. Despite a through search both in the MOD and at Boeing in Philadelphia, we have been unable to find any record of this incident.

Question 675 et seq: RAF Odiham and Boscombe Down—Technical Issues and Relationships

  Sqn Ldr Burke, in response to a question from the Chairman, took the opportunity to highlight his recollection of the concerns of pilots at Boscombe Down and RAF Odiham over the Chinook MkII, and their apparent unwillingness to fly this aircraft. Sqn Ldr Burke also indicated that relationships between RAF Odiham and BoscombeDown were perhaps strained. Both of these recollections are at variance with those of Wg Cdr Cooke and Gp Capt Crawford, the Station Commander at this time. As with the matter of Sqn Ldr Burke's alleged exclusion from the Board of Inquiry process, the Committee might wish to put these to Gp Capt Crawford during his evidence session on 7 November.

Question 705: Control Jam

  Sqn Ldr Burke expresses his opinion that there was a technical malfunction of some kind, and that this was the most likely cause of the accident. Relating to his personal experience he postulated that when an aircraft has been in straight and level flight for some while, a latent fault could develop which would not be discovered by the handling pilots, until a manoeuvre was attempted.

  To create the type of emergency put forward by Sqn Ldr Burke, it would be necessary for all four controls to jam simultaneously. The systems design and construction are such that this is virtually impossible as a result of component failure. Indeed the probability of a failure of two channels simultaneously was put to the Fatal Accident Inquiry as being one in 1,000 billion flying hours and that the design probability of both pitch and roll channels jamming simultaneously is one in a million billion billion flying hours. The probability of a loose object being able to jam all four control runs is currently being examined by Boeing. We will report their conclusions to the Committee when they are received.

  On the specific matter of any control jam remaining unknown to the handling pilot in a long period of straight and level flight, it is pointed out that the air conditions during the Chinook ZD576 flight were turbulent. Recent flights in a Chinook MkII in such weather conditions have conclusively demonstrated that the handling pilot is constantly required to make control inputs and adjustments. It is not possible for the catastrophic total control systems jam put forward by Sqn Ldr Burke to have remained unnoticed. (Moreover, such a jam would have had to clear itself before the final flight manoeuvre).

November 2001

  Recently, I have been apprised of the contents of Squadron Leader Robert Burke's statement made on 16 October 2001, to the House of Lords' Select Committee into the crash of Chinook ZD576. In particular, I refer to Squadron Leader Burke's recollection of an alleged meeting in which he recalls that I gave him "a direct order | not to discuss the crash with anyone". I have no recollection of the meeting he described in his evidence and at no time during my tenure as his superior, which covered the period of the Board of Inquiry into the crash of Chinook ZD576, did I ever give him a direct order not to discuss the crash of Chinook ZD576 with anyone. However, I recall a casual meeting outside my office when Squadron Leader Burke asked if he should present himself to the Board of Inquiry in the capacity of an expert witness. I recall that I advised Squadron Leader Burke that should the Board of Inquiry require his expertise they would no doubt ask for his assistance.

J A Cooke OBE

Wing Commander

5 November 2001