The Nimrod Review - Official Documents

The Nimrod Review
52
4.36
This confirms that combustible fluids can gather under the muff; both hydraulic fluid and fuel in this case.
Since the SCP has not been used since September 2006, it is difficult to determine when this incident may have
occurred. Regular maintenance checks of the SCP on the ground were carried out until July 2008 and would
only have used low engine power settings consistent with the results of the chemical analysis. It remains a
possibility that, under the normal operating temperatures of the SCP pipe experienced before September 2006,
the hydraulic fluid could have been ignited, as indeed would fuel. The precise sequence of events will never be
known but, in my view, it is powerful corroboration of the BOI’s finding on likely ignition point and proof that
fluids can, and do, enter the SCP elbow muff (see Figures 4.9 and 4.10).
Figure 4.9: XV255 Flexible Muff
Note: the muff shown on the photograph was the item taken off XV255 and shows the
scorching. The part is, however, not the correct muff for this bellows and is in fact 6cm
longer then the correct part. Thus, it may give the incorrect impression that the muff is
designed to cover the gap between sections of Refrasil.
Gap
Gap
Deterioration in outer
surface of muff
Blackening caused by 'pyrolysis' of
OX87/OX7
SCP elbow
Gap
Figure 4.10: SCP Expansion bellows/flexible muff (showing deterioration)