History of the Flight
At 1301 Pacific Daylight Time, a Helijet International Inc. Sikorsky S-76A helicopter (registration C-GHJT, serial number 760052) departed Masset Airport, British Columbia, for a fishing lodge on Langara Island. The flight carried one pilot and one passenger. On short final approach to the lodge at 1319, a loud bang was heard, the engine-out warning horn sounded, and the No. 2 engine (Allison/Rolls Royce 250-C30S) lost power. At the time, the helicopter was approximately 75 feet from the helipad and 49 feet above the water, with an indicated airspeed of about 14 knots. The pilot was adjusting engine torques when the power loss occurred.
Ditching
The pilot pulled up on the collective to reduce the rate of descent and pitched the nose down in an attempt to land on the helipad. Determining that a safe landing on the small floating helipad was not possible, the pilot stopped forward flight and ditched in the water beside the helipad with the emergency flotation system deployed. The helicopter settled on the water alongside the helipad. After shutting down the helicopter, the pilot noticed it listing nose down and to starboard. The pilot and passenger evacuated into a small boat dispatched to assist; no one was injured.
Post-Ditching Events
About four minutes after evacuation, the helicopter rolled inverted in the water. The emergency locator transmitter activated for approximately four seconds. The flotation system had deployed but did not keep the helicopter upright after rotor shutdown. The starboard nose float cells deflated due to a failure of a bonded seam, which was degraded. The seam failure caused all cells in the float to deflate. Additionally, a tear in the starboard nose float may have resulted from contact with objects in the water or during recovery. As the helicopter listed, extra load on the starboard main float likely punctured or tore it, leading to deflation and the subsequent imbalance that caused the helicopter to invert.
Findings
The investigation found that the No. 2 engine outer combustion case failed in flight due to a fatigue crack that was not detected using the recommended inspection method and intervals. This resulted in power loss after the landing decision point. The pilot conducted a controlled ditching, but the flotation system did not maintain upright attitude because the starboard nose float bonded seam was degraded and failed under ditching forces. The recommended inspections for the engine outer combustion case and the emergency flotation system were found to be inadequate for detecting cracks and assessing float condition, respectively.