TSB IMAGES
The PIC came on the controls to assist with the
recovery as the PF applied full-aft cyclic. The helicopter dropped 1,400 ft. in just over 10 seconds, a rate of 8,220 ft. per minute. Loose items, including a spare headset, a handheld radio, a flight manual, and a lunch box, “launched forward from the rear cabin and struck the pilots on their helmets,” knocking the PF’s visor over his eyes. Several gauges broke loose from the instru- ment panel.
corner as their emergency-landing site just before the No. 2 engine-out indicator lit up. Still 1.2 nm from their intended landing point and struggling with the controls as they descended through 900 ft., they picked out a closer spot to land. The PIC activated the emergency locator transmitter (ELT), and the PF made a Mayday call that was received by nearby aircraft but not by air traffic control. The pilots lost yaw control on final approach, and the helicopter began spinning to the right as it descended. The PF pulled both throttles to idle and raised collective to cushion the impact as they descended into the trees. The aircraft hit the ground and rolled inverted onto a rocky ledge about 270 ft. above sea level; ruptured fuel lines leaked Jet A onto the pilots. The PIC helped the PF free a foot pinned in the footwell, and they evacuated the cabin. Nearby residents responded to the scene and transported both to the hospital.
The Investigation All the wreckage was found within an 80-ft. radius of the fuselage, confirming the helicopter’s near-vertical descent. The fuselage was three-quarters inverted in a steep, nose-low attitude. The tail boom was severed at its mounts and found uphill, pointed in the opposite direction.
One main-rotor blade was broken off while the other
was essentially intact. The tail-rotor drive shaft and its cover were severed 15 in. from their aft end, consistent with a main-rotor blade strike, and matching damage on the tail-rotor blades’ trailing edges and the vertical stabi- lizer confirmed the tail rotor was spinning freely at impact. The main-rotor mast showed deformation from “sig- nificant contact” with its static stops, indicative of mast bumping that stopped short of catastrophic separation. Both engines, their accessories, and the transmis-
The pilots regained some control 0.6 nm west of the coast of Bowen Island at about 1,400 ft. but found the flight controls extremely stiff. A caution light illuminated, indicating insufficient hydraulic pressure; in the chaos, neither pilot was able to see which hydraulic system had failed. They chose a large field on the island’s northwest
54 ROTOR DECEMBER 2022
sion were shipped to the manufacturer’s facility in Saint- Hubert, Québec, where all test runs were normal and no stored data indicated any in-flight anomaly. A tear- down inspection of engine No. 2 confirmed it wasn’t running at impact. Pratt & Whitney Canada confirmed that if the helicopter rolled beyond 90 degrees toward inverted, unloading the main rotor and risking an over- speed, the engine governors would reduce or shut off fuel flow to bring main-rotor rpm back within limits. A roll beyond 90 degrees could also allow air to enter
the hydraulic systems via their unpressurized reservoirs, resulting in degradation or loss of hydraulic boost to the flight controls. No anomalies were found in the hydrau- lic system’s pumps, filters, or fluids, or in the tail rotor.
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