If it wasn’t so serious it might have been funny.

Water leaking from a galley appliance put the 360 souls aboard QF2 in mortal peril on Monday afternoon as the Boeing 747-400 was descending toward Bangkok from London.

It seeped into the only spot inside the airframe where the power feed from four engine driven generators comes together to drive the main electrical system, and shorted it.

The cause of the seepage? A drain and drip barrier which informants claim wasn’t replaced after the jet underwent maintenance in Sydney.

A safe landing was made after 15 minutes running on a one hour battery and invertor back-up system. The professionalism of the pilots and cabin crew was of the highest standard. They dealt with a bungle that could have ended in disaster had the supply been cut off at cruising altitude, especially if at night and far from an adequate emergency runway, with most instruments no longer working and little if no engine power and a host of electrically assisted processes.

What is in the gun now is the calibre of Qantas maintenance in Australia and the capacity of management to ensure all jets are correctly maintained and airworthy.

Late last year Qantas workers at Melbourne topped up the emergency oxygen system in one of its 747s with nitrogen supposed to be used on the tyres.

It is an error that would have swiftly incapacitated both pilots in an emergency in which they put on the masks because of a cabin depressurisation or fumes or smoke in the cockpit.

The independent safety investigator the ATSB decided not to inquire into that deadly screw up but has taken up this latest incident.

And at CASA which favours the self-administration of safety rules, the question that the new government might reasonably ask is when and how often have its inspectors actually checked that all of the work that is signed off as being done on a Qantas jet is actually being done. A large fibre glass drainage shield is pretty hard to overlook.

Is there another explanation for the QF2 incident? Qantas clearly doesn’t think so. Within hours of the jet being inspected in Bangkok every one of its 747s was specifically checked before departure for missing items of plumbing.