Dynamic Aviation

The airplane was flying in instrument meteorological conditions at flight level 200 (about 20,000 feet), and a large area of thunderstorm activity was located to the northwest. About 20 miles from the thunderstorm activity, the airplane began to encounter moderate turbulence and severe icing conditions. The pilot deviated to the south; however, the turbulence increased, and the airplane entered an uncommanded left roll and dive. The autopilot disengaged, and the pilot's attitude indicator dropped. The pilot leveled the airplane at an altitude of 8,000 feet and landed without further incident. Subsequent examination revealed that one-third of the outboard left elevator separated in flight and that the empennage was substantially damaged. Meteorological and radar data revealed the airplane entered an area of rapidly intensifying convective activity, which developed along the airplane's flight path, and likely encountered convectively-induced turbulence with a high probability of significant icing. The effect of icing conditions on the initiation of the upset could not be determined; however, airframe structural icing adversely affects an airplane's performance and can result in a loss of control.

The twin engine aircraft departed Imbaimadai for a geophysical research mission on behalf of a Canadian company, carrying one passenger and two pilots. The accident occurred in unknown circumstances and the aircraft was missing. SAR operations did not find any trace of the aircraft nor the three occupants.

The first officer reported that during cruise flight, both propeller secondary low pitch stop (SLPS) lights illuminated, indicating the SLPS system prevented both propellers from going below the low pitch hydraulic mechanical stop. The right occurred first, then the left approximately 1 minute later. Emergency procedures to correct the condition were ineffective. The right propeller feathered at some point during the flight, and the first officer reported that while operating single engine, they experienced a problem with the propeller governor. The flight proceeded direct to an airport with short runways approximately 3.2 nautical miles (nm) northwest of their present position, rather than to an air carrier airport located 8.5 nm away. The captain entered a close-in right base to runway 35 (2,688 feet long runway), while flying at 155 knots (51 knots above single engine reference speed). He turned onto final approach with the landing gear and flaps retracted, but overshot the runway. The airplane contacted a taxiway near the departure end of intended runway, and then collided with several obstacles before coming to rest at a house located past the departure end of runway 35. A post crash fire consumed the cockpit, cabin, and sections of both wings. Post accident examination of the airframe, engines, and propellers revealed no evidence of preimpact failure or malfunction. No determination was made as to the reason for the annunciation of both SLPS lights.