Fatal Superstall During Production Test Flight (G-ARPY)

Flight Operations and Test Schedule The aircraft departed Hatfield at 1652 hours for the first of a series of production test flights intended to qualify for a Series Certificate of Airworthiness. The planned schedule included stalling tests if the aircraft and flight conditions were suitable. After takeoff, the aircraft climbed toward the northeast and, by about 1830 hours, had completed most of the flight test schedule before beginning the stalling tests. Three approaches to the stall were made to check the stall warning and stall recovery systems. The flight engineer’s log recorded that, with the aircraft in the landing configuration, the stick shaker operated at 102 kt and the stall recovery system at 93 kt. The fourth stalling run was made at 11,600 ft, still in the landing configuration, but the stall warning and stall recovery systems had been made inoperative in accordance with the test schedule. Radio telephony communication with the aircraft consisted only of routine messages until 1834 hours, when the pilot-in-command reported, “We are in a superstall at the moment.” This was the last radiocommunication received. At about that time, the aircraft was seen over Felthorpe flying very slowly, heading southwest at about 10,000 ft. The nose was observed to rise 30 to 40 degrees, and the aircraft began to turn to port. The starboard wing then dropped sharply, and after a short burst of engine power, the aircraft entered a flat spin to starboard. The spin continued, with the aircraft turning once every 6 to 8 seconds, until it reached the ground about a minute and a half later. All four crew members were killed.