The Nimrod Review - Official Documents

10A.51
Chapter 10A – Nimrod Safety Case: The Facts (Phases 1 and 2)
Although a Fault Tree for Uncontrolled Fire/Explosion was included in Annex A, owing to the multitude of
causes of fire and explosion throughout the aircraft, it was agreed at the workshop that expanding the
Fault Tree below the top level fire and explosion events would not be effective or productive. Instead, it was
decided to address the fire hazard by using the alternative ZHA approach. After this ZHA exercise had been
undertaken, a more detailed fault tree for Uncontrolled Fire was drawn up in the interests of completeness.
This Fault Tree listed the general areas in which an “Uncontrolled Fire” might occur, including the fuselage,
wings, empennage, APU bay and landing gear bays, and analysed the various ways in which the three
necessary ingredients (ignition + fuel + oxygen) might combine in e.g. the Wing Dry Bays:
10A.52 The FTA was the only piece of analysis in the entire NSC process that was carried out jointly, i.e. with
participation by BAE Systems and Nimrod IPT personnel (which included a former Nimrod pilot). It benefitted
from this operator input.
25 September 2002: Nimrod IPT formally authorises BAE Systems to proceed with Phase 1
10A.53
On 25 September 2002, the Nimrod IPT authorised BAE Systems to go ahead and produce Phase 1 of the
NSC for the price quoted. BAE Systems was tasked by the Nimrod IPT and undertook to produce a Safety
Case for the Nimrod MR2 and R1 to achieve compliance with JSP318B (Edition 4). 42 The start date for Phase
1 was November 2002 and the finish date was initially 14 March 2003, but subsequently slipped to 18 April
2003.
December 2002 and March 2003: BAE Systems’ zonal inspection visits
10A.54
Zonal inspections were carried out by BAE Systems’ personnel at RAF Waddington between 10 and 12
December 2002 and at RAF Kinloss between 11 and 12 March 2003. At RAF Waddington two Nimrod R1
aircraft were inspected: XV249 undergoing a Minor service and XW664 undergoing a modification. At RAF
Kinloss three MR2 aircraft were inspected in different states: XV248 on the flight line; XV227 undergoing
Minor maintenance; and XV236 undergoing Major maintenance and therefore in a stripped down condition.
Given the scale of the task, these zonal inspection visits were short. (It should be noted that the zonal
inspection visit to RAF Kinloss in 2008 for the review of the NSC lasted much longer but only involved 11
zones.)
42 PDS Task 16 3151) BAE Task No. 26-3244 – Nimrod Baseline Safety Case (Phase 1), dated 4 September 2002.
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