Incident Overview
On the day of the accident, a Eurocopter AS 350 B-2 (registration C-GSSS) operated by Expedition Helicopters Inc. was transporting drilling and seismic personnel between Butler Lake and Straight Lake in Ontario. The aircraft carried one pilot and four passengers. During the climb-out from Butler Lake, the helicopter leveled off at approximately 800 feet above ground level when the pilot experienced two distinct yaw kicks in the rudder pedals. These were immediately accompanied by a rotor overspeed warning horn.
Engine Failure and Emergency Landing
Following the initial warnings, the engine suffered a total loss of power, triggering a low rotor rpm warning. The pilot briefly scanned instruments before initiating an autorotation. Unable to reach the intended landing zone, the helicopter touched down hard in shallow water near the shoreline of a small lake. The impact caused substantial damage to the tail boom and tail rotor but did not ignite a post-crash fire. All occupants exited the aircraft unhampered; the pilot and two rear-seat passengers were uninjured, while the other two sustained minor injuries. The emergency locator transmitter activated upon impact.
Investigation Findings
The investigation focused on the Honeywell LTS101 700D–2 turbine engine. Test runs at a facility confirmed that the power turbine (PT) governor failed to maintain specified speeds, allowing the engine to overspeed. Teardown of the PT governor revealed that the spool bearing (part number 2523973N) had completely failed after only 228 hours of operation. Microscopic analysis identified diamond particles within the bearing remains, which likely caused excessive friction and heat, degrading lubrication and leading to failure. This specific type of bearing failure has been associated with hard-particle contaminants in units manufactured between 2006 and 2008.