Updated The world’s peak air safety authority, America’s FAA, has ruled that a cabin oxygen system used in some Boeing 777’s, must be changed to prevent the risk of a flash fire breaking out.
The relevance of this to MH370 hasn’t been established.
The airworthiness directive or AD, was published without fanfare last Thursday September 8 and takes effect this Thursday September 15. It is Docket No. FAA-2016-9047.
The news has broken the day after an apparently burned potential piece of wreckage from MH370 was handed to Australia’s air safety investigator, the ATSB, by US lawyer Blaine Gibson, in Canberra.
Mr Gibson has spent months seeking and in some cases personally finding suspected and later proven fragments from inside and outside the crashed 777 which have washed up on shores in Mozambique, Madagascar, Tanzania and South Africa. Other parts have been recovered from locations in Mauritius and La Réunion.
However while the ATSB determines the wishes of Malaysia in relation to Mr Gibson’s critically important discovery of a burn marked panel, the US safety regulator, the FAA, has acted to prevent what it calls an “oxygen-fed fire in the passenger cabin.”
A long campaign by John Sampson, a former editor-in-chief at Air Safety Week, concerning the possibility of a short term oxygen fire flare triggering the ultimate destruction of MH370, began soon after the flight disappeared with 239 people on board on March 8, 2014 while on its way from Kuala Lumpur to Beijing. (This corrects information in the initial post.) In its supplementary information the FAA says:
This AD was prompted by a determination that the low-pressure oxygen flex hoses in the gaseous passenger oxygen system can potentially be conductive. Conductive oxygen hoses in the flight compartment were addressed previously in AD 2012-13-05, Amendment 39-17107 (77 FR 41045, July 12, 2012).
The gaseous passenger oxygen system equipped with therapeutic oxygen is not continuously pressurized and must be activated by the flightcrew. Exposure to electrical faults, such as unintended short circuits, can result in localized electrical heating of the low-pressure oxygen flex hoses. This condition, if not corrected, could result in electrical current passing through the low-pressure oxygen flex hoses, which can cause flex hoses to melt or burn, and a consequent oxygen-fed fire in the passenger cabin.
It’s important to cut through the clutter in the FAA’s terminology, which Mr Sampson does at length in this technical and in parts polemical article. This is about a cabin oxygen supply system that could burn passengers to death in a short period of time, yet leave a jet capable of flying for hours.
Part of Mr Sampson’s article concerns his disagreement with the Pprune pilot and pretend pilot forum, and accusations that Boeing has in this and in an earlier oxygen flare fire incident, sought to manage regulatory recognition of the seriousness of the risks to do the least harm to its interests. Readers should make their own minds up about those matters, but what matters above everything else is a now officially recognised threat to air safety.
Mr Sampson has identified a potential risk to safety of flight in Boeing’s cabin oxygen supply systems, and whether or not it was applicable or a related factor in the MH370 disaster, it was a sufficiently grave threat for the FAA to act.