The Nimrod Review - Official Documents

Chapter 10B – Nimrod Safety Case: The Facts (Third Phase)
10B.54 The two Nimrod specialists on the A(2) desk, Witness AB [MOD] and Witness X [MOD] , had nearly four
decades of experience on the Nimrod between them, and a comprehensive knowledge of the aircraft and its
systems. Witness AB [MOD] had worked on Nimrods since 1974 for 28 out of his 38 years in the RAF, and
spent nine years teaching airframe systems at the Nimrod Maintenance School. Witness X [MOD] was an
airframe engineer by training and had spent 11 years at RAF Kinloss (1986 to 1997). In 1986, he completed
the Nimrod ‘Q’ annotation course which covered all aspects of Nimrod airframe related systems and then
spent six years in the Nimrod Major Servicing Unit. In 1992, he moved to the Nimrod Undercarriage Bay. In
August 1994, he was promoted to Chief Technician and became a team leader in Nimrod Major Maintenance.
When deep maintenance was transferred to industry (FRA) in 1995, he moved to Engineering Plans and
Records at RAF Kinloss. During all this time he gained a very detailed knowledge of the Nimrod airframe
and systems, including the fuel and air systems. I am satisfied that neither individual could, or would, ever
have made such a fundamental mistake. I have no doubt if either of them had been specifically asked for
information as to what, if any, fire mitigation controls existed in each of the 21 zones in question, they would
not only instinctively have known the answer for many of the zones, but also double-checked in the Master
Maintenance Schedule (MMS) and Aircraft Publications (AP) held on bookshelves behind them. Equally, if
anyone else on the Airframe Desk had been asked the same question, they would have referred the request
to the Nimrod specialists on the A(2) desk, or themselves had reference to the MMS and AP.
Zonal system
10B.55
In any event, it is a difficult mistake to make in relation to one or two zones, let alone 17 in total. As I
have said, Nimrod specialists would be familiar with the location of many of the zones. The zone numbers
can be easily checked in the MMS. The ‘zonal’ system of identifying parts of the aircraft was introduced
for the Nimrod in the late 1980s with Reliability Centered Maintenance (RCM). It is taught at the Nimrod
Maintenance School. All zone numbers are three digits long and follow a logical pattern: the ‘100’ numbers
cover the upper fuselage; the ‘200’ numbers cover the lower fuselage; the ‘300’ numbers cover the tail unit;
the ‘400’ numbers cover the engines; the ‘500’ numbers cover the port wing; the ‘600’ numbers cover the
starboard wing; the ‘700’ numbers cover the undercarriage; and the ‘800’ numbers cover the doors, including
the bomb bay doors. 8 The following standard MMS diagrams (Figures 10B.1 and 10B.2) illustrating the zones
were also to be found reproduced in e.g. BAE Systems’ BLSC (Phase 1) Zonal Hazard Analysis Report. 9
8 The zone numbers refer to the MR2; there are differences between MR2 and R1.
9 Report No: MBU-DEF-R-NIM-F5-0538
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