What happened
On 1 April 2009, an Aerospatiale (Eurocopter) AS332 L2 Super Puma, registration G-REDL, was conducting an offshore operation approximately 11 nautical miles northeast of Peterhead, Scotland. During the flight, the aircraft experienced a sudden and catastrophic mechanical failure within its transmission system. This failure led to the loss of control, resulting in the aircraft impacting the sea. The accident resulted in fatalities and significant damage to the airframe.
The investigation
Investigators from the AAIB conducted a detailed examination of the wreckage and the aircraft's maintenance history. The technical inquiry focused heavily on the main rotor gearbox (MGB) and the epicyclic module. The investigation scrutinized the condition of the second stage planet gear and analyzed data from the Health and Usage Monitoring System (HUMS).
Engineers examined the physical state of the transmission components, specifically looking for evidence of fatigue or debris. The investigation also reviewed maintenance activities performed on the aircraft, including a recent inspection and maintenance session conducted on 25 March 2009, to determine if any underlying issues had been identified or overlooked during routine servicing.