After borescope inspections like this one carried out on the no. 2 Rolls-Royce Trent 900 engine of VH-OQC in November 2010, an oil tube started leaking oil. Photo: Will Horton
Inspections on A380-powering Rolls-Royce Trent 900 engines carried out in the wake of last November's uncontained engine failure on Qantas flight 32 were followed by a string of separate incidents involving low oil pressure that required engines to be shutdown in-flight, the Australian Transport Safety Bureau says in a report.
When the first such Qantas incident occurred in February, a month after Qantas and Rolls-Royce deemed the A380 fleet safe to resume full operations, the incidents seemed uncanny. But they were systemically related.
The post-QF32 inspections involved a borescope inspection of the high pressure/intermediate pressure section, known as module 51. To access that area, an external HP/IP oil tube had to be removed, as was done on the number four engine of VH-OQC, the Qantas A380 involved in the February mid-flight engine shutdown.
Twenty days after the QF32-mandated inspection, the February event occurred, after which an inspection found that the same oil tube removed twenty days prior for borescope inspections was leaking oil at the top of its connection to the engine case.
The tube's nut attachment had a torque, a scientific measurement of force relative to distance, of 80 pound force/inch, one-third the required measure of 240. There had been no other maintenance to the engine, and the ATSB says there have been six other oil tube leaks due to low torque of the attachment fitting, all occurring after the removal of the oil tube to facilitate a borescope inspection.
Before anyone uses this leaking oil to fuel a side of the Qantas/engineering union dispute, the ATSB critically notes the oil leaks were on Qantas and another undisclosed Trent 900 operator (either Lufthansa or Singapore Airlines). Additionally, "Specific torque procedures for the re-installation of the tube were required on completion of the borescope. A review of the operator's maintenance documentation, confirmed the correct installation procedure had been carried out."
Perhaps Rolls-Royce is to blame, again, or the documentation was somehow not accurate, intentionally or not. Since this incident is so far neutral in blame, it is worth contextualizing it in the engineering union dispute.
Both Qantas and the union are making accusations with little substantiation. Steve Purvinas, the federal secretary of the Qantas licensed aircraft engineers union, has circulated a letter listing key maintenance failures at the much-derided overseas maintenance facilities Qantas uses. Although he indicates there is evidence of claimed shoddy work, none is given. Why might he hold back? Some say releasing evidence indicating as much could result in Qantas releasing evidence indicating shoddy work done in Australia by engineers Purvinas represents.
In the Rolls-Royce Trent 900 affair, Qantas had no difficulty speaking out against Rolls and even, possibly, leaking to a Four Corners documentary information about previous Trent 900 problems, albeit unrelated to QF32. Qantas' tactics have made it look very good in the limelight.
The result of the union and Qantas management giving evidence to maintenance quality would not cast one ahead of the other in the public's eye, but instead make each an organisation to be avoided.