It is not unusual that parts fall off aircraft in flight, but it is extremely uncommon that they cause a decompression of the passenger cabin.

In this instance an outer skin panel close to the wing and adjacent to one of the forward cargo hold doors separated from the rest of the airframe. Pictures of the aircraft clearly show that this was a system failure rather than being caused by, for example, an internal or external explosion. The panel in question appears to have been ripped away cleanly by the passage of the wind over the skin of the aircraft.

For this to occur, the indication is that a fault, either in manufacturing or maintenance, occurred.

The skin of aircraft is made up of very many such panels, all of which are riveted and glued in place.

Where such riveting is faulty for whatever reason, conditions exist such that, over time, wear and tear weakens joints and inevitably leads to failure similar to that that occurred on board QF30. As the air accident investigators go about the business of determining the cause of this incident, a thorough examination of the zone where the rupture occurred will be carried out. The focus for investigators will most likely rest on metal fatigue either within the skin sections or the riveting holding the panel to remainder of the airframe.

Boeing, the manufacturer of the 747-400 series of aircraft, as well as other airlines operating this type of aircraft, will be watching the progress of the investigation closely.

Should a flaw emerge that requires remedial work in other 747-400 aircraft operating around the world, then instructions will be delivered promptly to ensure that the remainder of in-service aircraft are as safe as they can possibly be.

Chris Yates is principal of Yates Consulting and civil aviation editor, Jane’s Information Group

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