Helikopter Service Flight 451

On 8 September 1997 Flight 451, a Eurocopter AS 332L1 Super Puma, from the Norwegian helicopter operator Helikopter Service, crashed into the Norwegian Sea, 100 NM northwest of Brønnøysund, Norway. The aircraft was en route from Brønnøysund Airport, Brønnøy to Norne, an offshore Floating production storage and offloading vessel (FPSO). The accident was caused by a fatigue crack in a spline of a power transmission shaft connector, which ultimately caused the power transmission shaft to fail. All twelve people on board were killed in the crash.

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 2,000 ft, 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 1,800 ft and all on board were killed as a result of the impact. The wreckage sank and came to rest at a depth of 830 m.

All twelve people on board were killed in the crash.