Three more Trent 900s found with manufacturing defect

Melbourne
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Inspections on Rolls-Royce Trent 900 engines have found three additional powerplants with a fault in the oil pipe tube, indicating that the manufacturing defect behind the uncontained engine failure on a Qantas Airways Airbus A380 was not a one-off occurrence.

All three engines with faulty oil tube pipes "were removed from service for further examination," the Australian Transport Safety Bureau (ATSB) says. The three engines were on a Qantas A380 due for delivery this month, an in-service Singapore Airlines (SIA) A380, and a third unidentified powerplant understood to be with Lufthansa.

The oil tube pipe faults were found after inspections on 45 engines deemed "relevant", the ATSB says. The ATSB could not be reached for comment on what made those engines "relevant" of all Trent 900 powerplants. There are 92 Trent 900s in service in addition to spare engines and powerplants on aircraft awaiting delivery, according to Flightlobal's ACAS database.

Of the 45 inspected engines, 29 were on operating aircraft, eight were not installed on aircraft, four were due to be delivered on a new aircraft and four were on a flight test aircraft, the ATSB says.

A Qantas spokesman says "there was an anomaly with one of the stub pipes on one of the four engines" on an aircraft due to arrive in the coming weeks. He could not confirm the variant of the Trent 900 involved, but says "it wasn't a 'C mod'".

Industry sources have said the problem affects only the "A mod" and "B mod" variants of the Trent 900, and not the latest variant, the "C mod".

Qantas' spokesman says the stub pipe defect is unrelated to the carrier's announcement last week that 16 of its Trent 900 engines require "modification to the latest standard or full replacement".

"That is not related to the stub pipe issue," the spokesman says. "The only stub pipe [fault] we have found is on this aircraft awaiting delivery." He declines to specify why the 16 other Trent 900s require change.

The airline does not expect the oil pipe fault to have a significant impact on the aircraft's delivery. "We will take delivery of the aircraft in the next ten days," the spokesman says. Qantas also plans to take delivery of another A380 this month and two more early next year.

SIA changed a "B mod" engine last weekend "as a result of the inspections that were recommended by ATSB", a SIA spokesman says. The engine is now undergoing a detailed inspection, he adds.

Last Friday, the ATSB faulted a "potential manufacturing defect" with the Trent 900's oil tube pipe as the cause of the uncontained engine failure on 4 November. The pipe feeds oil to the high-pressure (HP)/intermediate pressure (IP) bearing structure.

ATSB chief commissioner Martin Dolan says Rolls-Royce "has issued a procedure for checking all the relevant engines to determine whether or not the problem that we have identified does exist in any of those engines."

In its report, the ATSB says the misaligned region of counter-boring within the stub pipe outlet produced a localised thinning of one side of the pipe wall. That led to an oil leak and subsequent fire that ejected the powerplant's IP turbine disc, sections of which penetrated the aircraft and caused structural and systems damage, it adds.