The Nimrod Review - Official Documents

The Nimrod Review
(2) Factual Errors
11.129 The factual errors identified in relation to Hazard H73 were not a one-off. The Review’s analysis of the other
Pro-Formas revealed that they also contained significant factual errors which materially affected the accuracy of
the analysis. By way of example:
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11.127.1 The Electrical Systems Pro-Forma for Zone 114 (the No. 6 fuel tank compartment) stated that it is
“serviced by visual and automatic smoke detecting systems in conjunction with an installed manual
fire extinguishing system”, but that the analogous Zone 111(the No 5 fuel tank compartment) “has
no dedicated fire prevention systems installed”. Both zones exist between the aircraft’s under floor
bays, which have smoke detectors and a fire extinguishing system, but none of these systems are
intended to detect, or extinguish, a fire within the fuel tank compartments. 53
11.127.2 Similarly, Mech Systems stated that for Zone 128 (the rear hinged fairing) fire “was considered in the
initial design and a fire detection (and protection on the R1) system was introduced”; there is no fire
detection system in the MR2 rear hinged fairing and it is separated from the bomb bay (which has
such a system) by a solid bulkhead. 54
11.127.3 The Electrical Systems Pro-Forma for Zone 128 stated that “the MR2 bomb bay fire protection system
does not extend as far back as the rear hinged fairing”. This is not correct. The bomb bay is actually
fitted with a fire detection system, not a fire protection system. 55 (Significantly, both these Pro-
Formas for Zone 128 were countersigned by the same person).
11.127.4 Both the Electrical and Mech Systems Pro-Formas for Zone 211 (nose equipment compartment)
indicated hazards from signal cartridges and fire extinguishers. There are, however, none in this zone;
they are in the neighbouring Zone 212. 56
11.127.5 The Electrical Systems Pro-Forma for Hazard H46, Zone 114 stated that the “yellow hydraulic pump
motor assembly” was installed within this zone. This is incorrect: it is actually within the neighbouring
Zone 113. 57
11.127.6 Similarly the engine fire extinguisher bottles are stated in section 2 of the Mech Systems Pro-Forma
for Hazard H68 as being within Zone 423/433, while they actually reside within Zone 513/613 (albeit
the error is pointed out in section 6). 58
53 In its written submissions to the Review, BAE Systems sought to explain this error by explaining that all of the analysis of fire hazards in the Pro-Forma
related to Hazard H45 (Zone 113) rather than Hazard H46 (Zone 114) and that the Pro-Forma for Hazard H46 was, in fact, a joint Pro-Forma for Zones
113 and 114. Even assuming that to be the case, it is an understatement, in my view, to say (as BAE Systems acknowledged) that “the format of this
proforma is not user friendly and could give rise to confusion when reviewed by a third party”.
54 BAE Systems agreed that this statement was inaccurate but suggested that, as the engineers involved in Phase 2 did not consider mitigation such
as fire detection/suppression when calculating hazard probabilities, the error would not have had any impact on the overall probability assessment
for the hazard.
55 BAE Systems’ response to this criticism was to acknowledge that the Pro-Forma could have been more clearly worded, but to assert that “it was
not intended in the proforma for the term ‘protection’ to mean ‘suppression’. In this case, the term ‘protection’ was used as a generic term meaning
detection and/or suppression (and therefore was making reference to the detection systems in the zone).”
56 BAE Systems acknowledged that the hazards cited were incorrectly designated in zone 211 whereas they should have been designated in zone 212
but sought to downplay the significance of this error by stating that the two subsumed hazards were nonetheless reviewed and analysed as part of
zonal hazard analysis Hazard H56 and that it analysis of zonal Hazards H56 and H57 (which concerned zones 211 and 212 respectively) would not
have altered had the two subsumed hazards been correctly designated.
57 In response to this criticism, BAE Systems again sought to justify the error on the grounds that the Electrical Systems Pro-Forma for Hazard H46 was
in fact a joint Pro-Forma in respect of zones 113 (Hazard H45) and 114 (Hazard H46), and the analysis within the Pro-Forma of the pump related to
Hazard H45 (and zone 113).
58 BAE Systems denied that the statement in this Pro-Forma was incorrect, stating that the subsumed Hazards H55 and H56 did not state that the
fire extinguisher bottles were located in the engine bay, but rather covered the potential risk of a leak of halon gas into the engine bay. It is difficult
to see, however, how the discharge of halon gas into the engine bay could be a ‘potential risk’ since discharge into the engine bay was their very
function to obviate risks.