Helikopter Service Flight 451

The accident aircraft was an AS332 L1 Super Puma helicopter, manufactured by Eurocopter (now named Airbus Helicopters), registration LN-OPG. == Background ==

At 06:00 a.m. local time (UTC+2), Helikopter Service Flight 451 took off from Brønnøysund Airport with two pilots and ten passengers, heading for the Statoil operated FPSO Norne. The route was a daily shuttle due to lack of accommodation on Norne during the busy period when the vessel was under commissioning. ==Accident==

The flight proceeded as normal until 06:50:07 hours when the engine overspeed light was observed for a short time. The co-pilot read out the corresponding information from the emergency checklist, before they continued the approach to land on Norne. At 06:52:41 hours the crew contacted Transocean Prospect, the oil platform that was handling radio communication with helicopters landing on Norne. At 06:54:42 hours they informed Bodø ATCC that they were leaving , with an estimated time of arrival of 07:05 hours. According to the helicopter's cockpit voice recorder (CVR), the abnormal indications recurred at 06:55:37 hours before "something strange" was observed at 06:55:55 hours. A thud was heard at 06:56:30 hours; then, after a loud crunching sound 1.7 seconds later, the crew lost control over the aircraft. The helicopter fell to the sea from around and all on board were killed as a result of the impact. The wreckage sank and came to rest at a depth of . == Summary of investigation findings ==

Following their investigation of the accident, the Norwegian Accident Investigation Board (AIBN) concluded that the cause of the accident was multiple fatigue cracks in the splined sleeve between the high-speed bendix shaft and the right-hand engine, which had caused damage to the engine overspeed protection system. The splined sleeve disintegrated, severing the high-speed shaft, which led to an overspeed of the right-hand power turbine which in turn burst, destroying the left-hand engine as well as to cutting control rods which made the helicopter uncontrollable. ==See also==