航空调查决赛

Flight Conducted Under:Part 91: General aviation – Positioning

Analysis

The flight crew, comprised of the pilot-in-command (PIC) and second-in-command (SIC), was

conducting a stall test in the airplane following the recent removal, inspection, and reinstallation of the wing leading edges and de-ice panels as part of routine maintenance. The airplane departed normally, entered a climbing right turn to the northeast, and leveled off about 20,000 ft mean sea level (msl). In its final minute of flight, the airplane entered a rapid vertical descent consistent with a flat spin and never recovered.

The airplane was mostly consumed by postcrash fire and was highly fragmented, which precluded a complete and thorough wreckage examination of the airframe and engines. A review of the flight data showed no anomalies with the flight controls or engines, as the flight control surface movements were consistent with the flight control inputs and engine performance matched the power lever movement.

Performance data indicated that before the airplane entered the spin, it decelerated and its pitch attitude increased, consistent with the flight crew preparing to perform their planned post-maintenance stall warning and identification system checks. The airspeed then slowed further, with flaps retracted for the first system check. Performance calculations showed that the stick shaker activated about 117.5 kts, one knot below the activation speed for the stick shaker at flaps zero. The stick pusher then activated at 113.5 kts, 3 kts above the stick pusher activation speed. Given the airplane’s weight and load factor, the shaker and pusher both activated at appropriate speeds; however, the airplane entered the stall at the same time the stick shaker activated, which provided no warning to the flight crew.

机翼污染

失速测试条件

失速试飞员资格

可能的原因和发现

事实信息

飞行历史

Pilot Information

Aircraft and Owner/Operator Information