Gearbox Pieces Critical To Investigation Never Recovered From The Ocean Floor

It may be impossible to determine if an accident in 2009 that resulted in 16 fatalities in the North Sea was preventable, according to an inquiry being conducted in Aberdeen, Scotland.

The accident occurred when the main rotor gearbox on a Super Puma aircraft reportedly failed during flight and the aircraft went down in the water. But divers were unable to recover a critical piece, a gear that may have failed, from the ocean floor.

The Evening Express newspaper reports that the accident inquiry board was told that without that critical part, it is likely impossible to know if the accident was preventable. AAIB inspector Mark Jarvis said that because "we fully don't understand the failure mode," he could not say with certainty that the accident was avoidable.

But after inspecting what was recovered from the seabed, Jarvis said “What we do know is that if the gearbox had been removed from service and sent to the manufacturer then during their overhaul procedure this gearbox would have been rejected.”

He said there was evidence of spalling, or metal-on-metal contact, in the recovered gearbox, but there was not the usual amount of debris that would normally be found in such a situation.

An attorney for Airbus Helicopters (formerly Eurocopter) which made the Super Puma said that it was unlikely that the gear failed, because if it had been defective, that would have shown up in previous inspections. But Jarvis said that, as unlikely as that may be, "the possibility remains it … may have contributed to this accident.”

FMI: www.aaib.gov.uk