S92, en-route, east of St John’s Newfoundland Canada, 2009

S92, en-route, east of St John’s Newfoundland Canada, 2009

Summary

On 12 March 2009, a Sikorsky S-92A crew heading offshore from St. John's, Newfoundland declared an emergency and began a return after total loss of main gear box oil pressure but lost control during an attempted ditching. The Investigation found that all oil had been lost after two main gear box securing bolts had sheared. It was noted that ambiguity had contributed to crew misdiagnosis the cause and that the ditching had been mishandled. Sea States beyond the capability of Emergency Flotation Systems and the limited usefulness of personal Supplemental Breathing Systems in cold water were identified as Safety Issues.

Description

On 12 March 2009 a Cougar Helicopters' Sikorsky S-92A (C-GZCH) on a flight from St John’s Newfoundland to the Hibernia offshore oil platform as CHI 91 experienced a main gear box malfunction. During an attempt to return, it became clear that a ditching would have to be attempted but this subsequently occurred at a high rate of descent 35nm east of St John’s. The helicopter was severely damaged and seventeen of the eighteen occupants drowned and the sole survivor sustained serious injuries.

Investigation

An Investigation was carried out by the Transportation Safety Board of Canada (TSB). The accident helicopter was fitted a Solid State MPFR (Multi Purpose Flight Recorder) which recorded both Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR) data. Recovery and data download was successful with the exception of an absence of recording from about 44 seconds before impact until just under 2 seconds from impact. Useful data was also successfully recovered from the Non Volatile Memory of both FCCs, both EECs, the HUMS, the Terrain Avoidance and Warning System (TAWS) and the Maintenance Data Computer. The Investigation did not find evidence of any pre-existing condition that would have prevented normal operation.

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