The Australian Transport Safety Bureau is investigating multiple power failures in the QF2 incident at Bangkok not the single failure which Qantas said was caused by water flowing from a blocked galley drain through a cracked drip shield over the aircraft equivalent of a junction box.

It is a significant distinction, and parallels intense speculation in the industry that something the pilots might have inadvertently done made a partial power failure go total as they completed their descent into Bangkok from London a week ago yesterday.

But no-one, especially the incident investigators, are blaming the pilots. The inquiry which includes maintenance performed on the jet in Australia, isn’t about blame but cause and prevention.

The pilots have been praised in many quarters for using their common sense and seizing the immediate opportunity to land rather than attempting to diagnose a crisis which has never been experienced in a Boeing 747 and for which there was no set and rehearsed procedure for solving.

The ATSB is not alone in grappling with the incident. There is disquiet but as yet no official response from Boeing over suggestions that the suitability of the 747 for long distance flights far from handy airports, such as the trans Pacific routes, needs to be reconsidered if the design is flawed by the risk of a single water leak taking out all of electrical power generated by four engines.

The real disquiet may be with procedures and priorities in Qantas maintenance. Why can’t it get basic plumbing right? Who profits from cutting out processes that would ensure drip trays are fixed, and that jets are not dispatched with drainage problems?

The near certain loss of the Qantas jet in question if it had experienced the same failure over the Pacific, or Antarctica, where it had been a week earlier, is emphasised in a partial list of critical functions of electrically driven functions posted on the Professional Pilots Rumour and Discussion network.

This list may be incomprehensible, but it is what remained powered during the 30-60 minutes of backup battery time. It is thus also a list of what would become unpowered. It shows the jet would subsequently be without most instruments, communications, anti-collision warnings, de-icing systems, windshield de-icing, radar, some airspeed and altitude data and bank and turn information.

Pilots tell Crikey the jet could have manually lowered its undercarriage. This seems academic.