Pressure bulkheads like those in the six temporarily grounded Qantas 737-400s are vital to safe flight. If they break apart the difference in pressure between the cabin interior and the external air pressure will destroy the jet.

Two are known to have ruptured in old and incorrectly repaired Boeing 747s, killing 732 passengers and crew in total.

On 12 August 1985, a Japan Air Lines flight become uncontrollable after its bulkhead failed, blowing away half of the tail and the hydraulic flight control systems.

It crashed on a mountain ridge killing 520 people in the worst single airliner accident yet, with four survivors being found after an unknown number of those on board died of exposure and injuries in the hours before rescue teams reached the scene.

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On 25 May 2002 a China Airlines (Taiwan) 747 broke apart over the sea killing all 225 people on board.

In both disasters blame was laid on a team of Boeing engineers who were called in by each airline to repair the bulkheads after the jets had suffered tail strikes in runway incidents many years before metal fatigue ultimately found the weak points left by shoddy maintenance.

It is not yet known if the lack of maintenance documentation found by Qantas will identify a failure to complete compulsory work on the 737 bulkheads or not.

Lack of compliance with the record keeping rules brings multi-million dollar fines in the US, even if the work is found to have been done.

For Qantas not to know what it has done to any of its unreliable fleet of jets and turbo-props is a scandal.

The protestations about the safety of the airline being made by David Cox, the executive general manager engineering, are worthless if he hasn’t got the paperwork to prove them.

Cox and the management team led by departing CEO, Geoff Dixon during the failed private equity bid are personally responsible for a situation where the Qantas network was left with diminished spare parts inventories and an inadequate engineering and maintenance resource that blind Freddy can reasonably associate with a string of frightening incidents — some of them very serious.

The gutting of the Qantas brand value by dirty and delayed aircraft cannot be explained away by bad luck, or unforseen circumstances, unless the failure of the bid to flog the carrier to a bunch of privateers who might well have gone broke by now is considered part of those misfortunes.

There is lot for Qantas to answer for in coming days and months when record profits have to be reconciled with the costs of restoring a damaged reputation.