Did they not know about the leak warning system or would it just not have detected a small leak?
It would not have detected a small gas leak which, by its very nature, would not rupture a fuel pipe, but might damage a seal within a coupling and create a small fuel leak, which then plays onto the hot pipe. The BOI has stated this in the report, but this possibility is disregarded as the most probable cause because the amount of fuel from a coupling would be smaller than blow-off or complete coupling failure and it would evaporate before it came into contact with the pipe for the required period for auto-ignition at 400 degrees (approx 1 minute).
Its all in the report.
Someone asked "what leak detectors?". I was referring to 5 hot gas leak detectors as descriptive terms for non Nimrod folk, to describe the Centre Section Overheat detectors, in that zone, set at 230 degrees.
Regards
Ed Sett