CEN23LA135

During a flight test, the unmanned aircraft’s flight control computer registered a low battery voltage reading and entered an automatic land in place flight maneuver. The aircraft was hovering over a large bush at the time and the ground station operator (GSO) attempted to override the system, but the system rejected the commands. The GSO attempted to change the land in place waypoint, but the system again rejected the command. The aircraft performed its land in place maneuver and collided with the bush, which resulted in the aircraft tipping over and coming to rest inverted. The operator reviewed the aircraft systems and found the low voltage threshold to be overly restrictive. In addition, software prevented the flight crew from overriding the land in place command and regaining control of the aircraft by changing the waypoint.

On March 14, 2023, about 1030 central daylight time, a Bell Textron APT70 unmanned aircraft, N314AL, was substantially damaged when it was involved in an accident near Mineral Wells, Texas. The aircraft was operated under the provisions of Title 14 Code of Federal Regulations Part 91 as a flight test. During the flight test, the aircraft returned to base and was in a transition to hover when the flight control computer registered a low battery voltage reading and went into an emergency automatic land in place flight command. The GSO attempted to override the system, but the system rejected the commands. The crew then noted the “F BATT CRIT LOW VOLT” warning illuminated, which initiated a descent for the aircraft to land at its present position. At the time, the aircraft was in a hover at an altitude of about 100 ft above the ground over a large bush when the Land Failsafe command was activated. A command was sent to the vehicle to override the landing command, but the ground control station indicated that the override command was rejected. The GSO then attempted to change the land in place waypoint, but the system again rejected the command. The aircraft performed its land in place maneuver and collided with a shrub, which resulted in the aircraft tipping over and coming to rest inverted. Substantial damage was sustained to the lower left wing section. The operator reviewed the aircraft systems and found the low voltage threshold to be overly restrictive. In addition, a software limitation prevented the crew from overriding the land in place command by changing a waypoint.