Directive Revised To Calculate "Average Wear" On Turbine Shaft To Determine Future Inspections

EASA reportedly revised its inspection standards for the Rolls-Royce Trent 900 engine three months before one catastrophically failed on a Qantas A380, forcing an emergency landing in Singapore recently.

The original requirements said airlines should calculate time between inspections for the turbine disc shaft based on the most worn spot on the shaft. The revised rules, enacted in August, allowed airlines to use average wear on the shafts. That led to fewer engine inspections, but EASA determined that it was "sufficient to prevent unacceptable wear."

The Sydney Morning Herald reports that, while the directive does not cover the exact part which failed on the Qantas flight, it is very similar, and is adjacent to the turbine that did fail, according to a former Embry-Riddle professor of aerospace engineering.

Rolls-Royce is reportedly replacing the relevant engine part, and that it is cooperating with aviation regulators on inspections. Airbus said that Rolls-Royce is equipping newer versions of the Trent 900 with software that will detect an oil leak such as the one that led to the failure and shut the engine down before it disintegrates. Airbus said it would ship the newer engines to Qantas from the production line. Airbus COO John Leahy denied that Rolls-Royce knew about the problem before the Qantas incident.

There is still no firm timeline for a return to service for the Qantas Airbus A380's. The Australian civil aviation authority will make that determination. The French news service AFP reports that Airbus CEO Thomas Enders said he expects that the Trent 900 problem will "impact deliveries, particularly in 2011" due to increased checks and recommended replacements. Still, Enders said, the reputation of the A380 "remains untarnished."

AFP also reports that two Singapore Airlines A380s have resumed flying following the replacement of the Trent 900 engines after one was found to have oil stains. One of the airline's super jumbos remains grounded. In all, Singapore Airlines operates 11 A380 aircraft.

FMI: www.airbus.com, www.rolls-royce.com, www.qantas.com