Cost of Qantas A380 Groundings Mounts

 - December 10, 2010, 5:54 AM
Investigators have determined that a misaligned region of counter-boring in the outlet of stub pipe that feeds oil to the Trent 900’s HP/IP bearing structure caused a localized thinning of one side of the pipe wall and eventual fatigue cracking.

Some five weeks after an uncontained engine failure forced one of Qantas’s six Rolls-Royce Trent 900-powered A380s to make an emergency landing at Singapore’s Changi International Airport, the bills continue to mount for the airline and engine manufacturer alike. Estimates by some financial analysts now place Qantas’s monetary damages at more than $200 million, as four of the airline’s A380s remain grounded until further notice.

The Federal Court of Australia has granted Qantas an injunction meant to ensure the airline can pursue legal action against Rolls-Royce in Australia if the sides fail to reach a financial settlement. Although the return to service on November 27 of a pair of Qantas superjumbos marked the end of the airline’s 23-day suspension of A380 operations, the airline continues to exhibit an abundance of caution as it delays the deployment of its remaining double-decker transports, perhaps into the new year. In a statement issued December 3, Qantas said it would voluntarily apply “a range of conditions that include not operating the aircraft across the Pacific until further operational experience has been gathered.”

At least the source of the problem became clearer when, on December 2, the Australian Transport Safety Bureau indicated that a misaligned oil pipe counter boring likely led to fatigue cracking, oil leakage and, ultimately, the engine fire that precipitated the explosion. 

As a result of the safety recommendation, Rolls-Royce immediately issued a service bulletin revision that incorporates assessment and engine rejection criteria for the measurement of potential oil-feed stub pipe counter-bore misalignment, and a tightening of the compliance timeframe from 20 to two flight cycles.

By December 8, engineers found problems with three of 45 Trent 900 engines that underwent inspection as prescribed in the bulletin. None of the engines installed on the two A380s in service with Qantas showed defects, according to the ATSB. However, inspectors at Airbus’s Toulouse factory found a “minor” problem, reportedly associated with an oil pipe, in an engine installed on one of two new A380s due to arrive at Qantas’s Sydney base some time around the middle of this month. Nevertheless, the airline does not expect the finding to delay delivery.  

The ATSB recommendation came a day before the bureau issued a preliminary factual report that confirmed far more damage to the A380 and a much more precarious emergency landing in Singapore than first thought.

According to the report, sections of the intermediate pressure (IP) turbine disc penetrated the leading edge of the left wing inboard of the Number 2 engine, resulting in damage to the leading-edge structure, the front wing spar and the upper surface of the wing. Another piece of turbine disc penetrated the left wing-to-fuselage fairing, resulting in damage to several system components, the fuselage structure and electrical wiring. Debris also struck the left wing’s lower surface, which caused a fuel leak from the Number 2 engine feed tank and left wing inner tank.

The damage to the wiring affected the operation of the hydraulic system, landing gear and flight controls. The pilots were also unable to pump fuel out of the rear tank, creating a potential c-g imbalance as the A380 landed at Changi International Airport. Meanwhile, the crew had to contend with the lack of reverse thrust from the Number 2 engine, inoperative leading-edge slats, limited aileron and spoiler control, lack of anti-skid braking in the wing landing gear and limited nosewheel steering.

Landing some 50 tons overweight, the airplane needed all but 500 feet of Changi International’s 13,123-foot runway to roll to a safe stop.

The drama didn’t end there, however, as the Number 1 engine continued to run and the left body landing gear brake temperature rose to more than 900 degrees. Emergency crews finally managed to drown the engine with firefighting foam two hours and seven minutes after the airplane landed.