NTSB Report Blames Clear Air Turbulence for United Airline Flight Injuries

Pictured: Couger-owned Sikorsky S-61N Helicopter
Click to view full size photo at Airliners.net
Contact photographer Phil Earle
On March 12, 2009, about 0926 ADT, Atlantic Daylight Time, a Sikorsky S-92A helicopter, Canadian registry C-GZCH, operated by Cougar Helicopters, impacted the waters of the North Atlantic about 28 miles east of Cape Spear near St. John’s, Newfoundland. There were two pilots, Pilot Matthew William Thomas Davis, 34, of St. John’s, Newfoundland and Labrador and First Officer Tim Lanouette, 48, of Comox, British Columbia, both of whomdied in the accident, and 16 passengers on board the helicopter. One passenger, Robert Decker, survived with serious injuries, but the other occupants were fatally injured. The helicopter was en route from St. John’s International Airport (CYYT) to an offshore oil platform in the Hibernia oil field. The pilot made a MAYDAY call due to a mechanical difficulty, and was returning to St. John’s at the time of the accident. Visual meteorological conditions prevailed at the time of the accident, and the sea state had 3 – 5 meter swells. An instrument flight rules (IFR) flight plan was filed.

The NTSB has recommended that any gearbox losing oil pressure should have the capacity to run dry for 30 minutes before failure. In the case of Flight 491, the elapsed time between the warning light and the ditching of the aircraft in the sea was 11 minutes. Two of the three main gearbox mounting studs were broken. When they broke, the helicopter lost oil rapidly and the gears began to overheat.

On March 23, 2009, Sikorsky released a bulletin that most of the world’s S-92TM helicopter fleet already had complied with the company notice to retrofit the aircraft’s gearbox oil bowl with steel mounting studs.