Fuel tank puncture: Qantas A380 'lucky' to escape catastrophe, say reports

New revelations have emerged of just how close the passengers and crew on board Qantas QF32 came to perishing in a mid-air aircraft explosion over Indonesia earlier this month.

Reports in the US have revealed that shrapnel from the engine blast punctured the fuel tank in the wing of the A380.

It appears to be a matter of sheer luck that the fuel - an Airbus A380 carries 310,000 litres - did not ignite and cause an explosion.

QF32 was bound for Sydney on November 4 with 433 passengers and 26 crew on board when the engine failed, forcing the A380's return to Singapore's Changi Airport.

Professor Adrian Mouritz, the head of aerospace and aviation engineering at RMIT University, said Qantas was "very, very lucky".

"If that fuel ignited, that aircraft would have exploded," he said.

Confidential preliminary reports seen by Fairfax Media reveal that high-velocity parts spat from the engine tore through a fuel line and wiring looms, punctured structural spars in the wing, struck the fuselage between the two decks of windows, hit the fuselage belly and tore through wing panels.

In the cockpit, pilots faced a "cascading series of critical system failures", the Associated Press reports, and were confronted with 54 flight system error messages to work through, a task that took 50 minutes to accomplish.

A weight imbalance caused as fuel leaked from the tank complicated matters further, the agency reports.

Wiring damage prevented the pilots from being able to pump fuel between tanks, and the plane became increasingly tail heavy, raising the risk of a stall.

"I don't think any crew in the world would have been trained to deal with the amount of different issues this crew faced," Richard Woodward, a vice-president of the Australian and International Pilots Association, is reported as saying.

"The amount of failures is unprecedented," he said. "There is probably a one in 100 million chance to have all that go wrong."

Meanwhile Qantas and Rolls-Royce were still "days away" from identifying which engines might have to be replaced, said the airline's chief executive Alan Joyce.

As many as 40 engines on the worldwide fleet may need replacing, including up to 14 at Qantas, he said.

The engine maker had not told the airline and Airbus about two series of production changes to the engine's internals, he said.

They are believed to be changes to a gear bearing and its oil supply system.

"What Rolls-Royce have done is that they have modified certain parts of this engine," Mr Joyce said.

"We and Airbus were not aware of it.

"We are hoping in the very near future to understand precisely the engines that need to be replaced ... but we are still a few days away from that."

Accordingly, he could not say when the A380 fleet would return to the skies.

New, replacement engines would be sourced from Airbus and Rolls-Royce.

"We are looking at engines from the production line; engines that are either in Toulouse (France) or Derby in the UK and we are looking trying to get those engines on to aircraft that need engines change," Mr Joyce said.

Rolls-Royce has only issued three carefully worded statements since the November4 engine explosion on QF32 and yesterday cancelled its press conference at the Zhuhai airshow in China, avoiding any awkward questioning.

When asked if there is a problem with disclosure at Rolls-Royce, Mr Joyce said:

"Since the incident occurred the relationship with Rolls-Royce has been excellent. If you look at engine incidents that have occurred in the past, in some cases, it has taken a very long time to have an understanding of what the root cause could be ... in some cases it could take a year.

"In this case we have gotten there very fast," he said.

The European Aviation Safety Agency maintains the Trent 900 engines are safe, as long as the agency's directives are followed.

"All the existing variants of the Trent 900 engine are considered to be safe," the agency's spokesman said.