During The Three Months Before The Accident Flight, The Gyroplane Was In Maintenance And The Pilot Had Not Flown

Location: Beverly, Massachusetts Accident Number: ERA23FA078
Date & Time: December 4, 2022, 11:35 Local Registration: N401GR
Aircraft: Rotorsport UK LTD Cavalon Aircraft Damage: Substantial
Defining Event: Inflight upset Injuries: 1 Fatal
Flight Conducted Under: Part 91: General aviation - Personal

Analysis: The sport pilot, who was also the owner of the gyroplane, had about 120 total hours of flight experience, all of which was in the accident gyroplane. During the three months before the accident flight, the gyroplane was in maintenance and the pilot had not flown. Surveillance video captured the accident sequence, and showed the aircraft in the initial climb. It  leveled off briefly before resuming its climb while displaying a significant left yaw. Shortly thereafter, the aircraft rolled to the right about 360° and impacted the runway. Recorded data from onboard avionics, as well as postaccident examination of the aircraft, did not reveal any evidence of mechanical malfunction or anomalies that would have precluded normal operation. 

The rudder trim tab was found undamaged by impact and bent about 30° to the right (left rudder force). The aircraft manufacturer cautioned that extreme sideslip could result in a loss of control. With the aircraft flying sideways, the side of the aircraft faces the oncoming airflow, creating increased drag that tends to swing the fuselage away from the direction of flight. The rotor disc is subsequently pitched down on the side of the aircraft headed into the oncoming airflow. With the airflow above rather than below the rotor disc, the aircraft can rapidly roll over toward the side of the aircraft facing the direction of flight unless urgent corrective action is taken. The reason that the pilot did not take appropriate recovery action  could not be determined.

Toxicological testing indicated that the pilot had used cannabis, but the timing of his last cannabis use or whether he was impaired by cannabis effects at the time of the accident could not be determined. It is plausible that the pilot’s overcorrection of the aircraft’s yaw may have resulted, in some part, from impairing effects of delta-9-THC; however, the pilot also had not flown in the three months before the accident. Thus, whether the pilot’s use of cannabis contributed to the accident cannot be determined. Additionally, the pilot’s autopsy findings were consistent with high blood pressure’s effect on the heart muscle. The pilot’s disease put him at some increased risk for a sudden impairing or incapacitating cardiovascular event such as heart rhythm abnormality. Such an event cannot be ruled out; however, witness accounts and airport video were not consistent with a sudden medical event. Thus, it is unlikely that the pilot’s heart disease contributed to the accident.

Probable Cause and Findings: The National Transportation Safety Board determines the probable cause(s) of this accident to be -- The pilot’s improper yaw control during the takeoff initial climb, which resulted in an excessive sideslip and a subsequent loss of aircraft control.

FMI: www.ntsb.gov