The controllability of the Qantas QF32 Airbus A380 when one of its a Rolls-Royce engines disintegrated after taking off from Singapore, was a constant issue for its pilots, according to the preliminary report into the incident by the ATSB.

However, it did remain controllable, and the flight deck was manned because of training and checking requirements by a total of three highly experienced captains (not one) as well as a first officer and second officer.

The report released this morning shows that a manufacturing defect in an oil stub pipe may have caused the most serious crisis on board a Qantas jet since a 747-400 came to rest in a golf course at Bangkok in 1999 after a botched landing.

The report says data recorded from the Rolls-Royce Trent 900 inboard engine that failed shows abnormalities began 49 seconds before its intermediate pressure turbine flew apart and sliced through critical parts of a wing, fuel tanks and fuel lines and control cabling, disabling half the jet’s hydraulic systems and seriously degrading other flight control functions.

The report doesn’t speculate on the difficulties a normal crew of one captain and a first and second officer might have experienced in dealing with the unprecedented and never anticipated consequences of an uncontained engine failure of this type.

But it makes it clear that the enlarged flight crew on duty methodically worked their way through the crisis, after telling Singapore Airport that they might need to make a rapid emergency landing at any stage in the nearly two hours the stricken jet was aloft.

The report helps set the stage for Qantas to recover a claim for $100 million or more from Rolls-Royce for the direct and consequent costs of the incident, and the grounding of the Qantas A380 fleet until last weekend as part of a process of fully understanding and dealing with the safety issues that arose.

Qantas expects to complete a new set of examinations this afternoon that will allow its gradual resumption of A380 flights to continue. Those additional tests were required after the ATSB yesterday identified a defect in the remains of engine that came apart in the incident.