PARIS (Reuters) – French investigators have called for a review of the design and maintenance of titanium alloy engine parts to ensure they guard against the risk of metal fatigue from an engine explosion on an Airbus AIR.PA A380 exactly three years ago.
The French agency BEA made this recommendation in a final report on the accident in which an Air France plane carrying more than 500 passengers lost the front part of one of its four engines as it flew over Greenland , before landing safely in Canada.
The move follows a perilous investigation involving a 21-month international air and ground search of the ice sheet to find a crucial fragment of titanium alloy, buried 10 feet below the surface and just three feet from a hidden crevice. .
The probe focused on the fan hub at the center of a 3-meter-wide fan in the front of the engine manufactured by Engine Alliance, part of General Electric. GE.N et Pratt & Whitney RTX.N.
The BEA said a recovered fragment showed tiny fatigue cracks in a titanium alloy called Ti-6-4 and urged regulators – the Federal Aviation Administration and the European Union Aviation Safety Agency – to perform a review of the design, manufacture, maintenance and certification processes. .
“Neither the manufacturer nor the certification authorities anticipated this phenomenon in this alloy when designing the engine,” said the BEA.
These recommendations from leading researchers should not be followed automatically, but they usually carry some weight.
Engine Alliance said it had already taken steps to address the results. Airbus said no flaws were found during inspections of other engines from the same supplier, one of two A380 engine makers alongside Rolls-Royce RR.L.
A Rolls spokesperson said she was convinced that the problems associated with the Engine Alliance part “cannot be attributed to any Rolls-Royce engine fan discs currently in service”.
Titanium alloy is widely used in the aerospace industry, the metal’s biggest customer because of its strength relative to the weight of each part and its ability to withstand high temperatures.
In the past, the industry has faced concerns about the manufacturing processes of titanium alloys after engine failure.
In 1989, a severe engine failure on a United Airlines DC-10 resulted in the deaths of 111 people during an attempted landing in Sioux City, Iowa.
This accident accelerated improvements in manufacturing methods for titanium alloy. But some engine experts have dismissed any suggestion that there is an industry-wide manufacturing problem.
During the operation in Greenland to find the missing A380 engine fragment, French, Danish and American specialists battled issues ranging from faulty generators to storms, buried tents and concerns about polar bears, according to a report shipping.
At one point, the team resorted to low-tech methods including bamboo sticks and concentrated juice to mark the snow after their high-precision positioning system failed, but the investigation also stimulated the development of new detection equipment.