The Nimrod Review - Official Documents

The Nimrod Review
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(2) The escape of fuel during Air-to-Air Refuelling (AAR) occasioned by an overflow from No. 1 tank
(from the No. 1 tank blow-off valve and/or vent pipe connection); or
(3) A hot air leak (from the Cross-Feed/SCP duct) causing damage to adjacent fuel seals.
7. In Chapters 5, 6 and 7 below, I consider each of these three mechanisms separately, on their
merits:
Chapter 5: LEAK FROM FUEL COUPLING
Chapter 6: OVERFLOW OR PRESSURE FROM AIR-TO-AIR REFUELLING
Chapter 7: DAMAGE FROM CROSS-FEED/SCP DUCT FAILURE
8. Each of these three sources of fuel is potentially relevant to the cause of the loss of XV230. Each
raises significant issues regarding the airworthiness of the aircraft over many years. Each raises
serious questions about the management of airworthiness by the various organisations involved.
Each gives rise to important lessons for the future.
9. I have concluded, in the light of all the evidence, that the probable sources of the fuel for the fire
which caused the loss of XV230 should be ranked as follows (i.e. in order of likelihood):
(1) The most likely source of fuel was an overflow during AAR (Chapter 6);
(2) The second most likely source of fuel was a leak from a fuel coupling in the starboard No. 7 Tank
Dry Bay (Chapter 5);
(3) The third, and only other viable, source of fuel could have been coupling damage caused by a
Cross-Feed/SCP duct failure, but this mechanism was in my view much less likely than (1) or (2)
(Chapter 7).
10. The ranking of the three potential sources of fuel should not detract from the potential causative
potency of each, or the lessons to be learned from what the investigation of them by the Review
has revealed.
Other theories
11. I have carefully considered various other alternative theories which have been put forward as to the
causal mechanism of the fire on XV230. In my view, none of these theories are viable or credible.
Although, in the absence of the physical evidence, nothing can be ruled out entirely, I am satisfied
that all such theories are far less likely than the BOI’s findings which, subject to the above ranking,
I accept.
Defective design
12. The Nimrod suffered from fundamental design flaws which played a crucial part in the loss of
XV230. There are three stages at which defective design occurred:
(1) First, the original fitting of the Cross-Feed duct to MR1s and R1s (1969-1975);
(2) Second, the addition of the SCP to MR2s (1979-1984); and
(3) Third, the fitting of permanent AAR modifications to MR2s and R1s (1989).
13. These three design flaws were contrary to sound engineering practice at the time and contrary to
design regulations in force in 1969, 1979 and 1989 respectively.