What happened
During a high-speed ground evaluation intended to test the fly-by-wire rudder actuator and minimum control speed (vmcg), the aircraft experienced a sudden loss of directional control. As the aircraft reached high speeds during its final test run, it unexpectedly veered to the left and lifted off the runway. The aircraft entered a left-hand turn and ascended to an altitude of approximately 250 feet before entering an uncontrolled state. The aircraft subsequently impacted the ground.
All seven occupants on board were killed in the accident.
Findings
Investigators identified a specific design element within the rudder actuator that contributed to the loss of control. This feature is programmed to eliminate hydraulic pressure from the actuator if the pilot's commanded rudder position differs from the actual actuator position for a set duration, allowing the rudder to trail aerodynamically. During the test, this actuator disengaged while the aircraft was in flight.
Several organizational and procedural failures were noted during the investigation:
- The company failed to perform a system safety review regarding the consequences of the rudder bypass feature across different flight regimes.
- No safety review was conducted for the vmcg testing procedure itself.
- The established flight test plan required engine power to be reduced if the rudder lost effectiveness, but this was not successfully implemented.
- The crew members had not been trained as experimental test pilots.
- The company permitted these experimental flight operations to take place at an airport located within a metropolitan area.