The Descent Rate And Airspeed Rapidly Increased To Near The Aircraft’S Maneuvering Limitations For Both Bank Angle And Airspeed

Location: Mokuleia, Hawaii Accident Number: ANC23FA003
Date & Time: November 5, 2022, 08:11 Local Registration: N444EZ
Aircraft: Airborne Windsports Edge XT-912L Aircraft Damage: Substantial
Defining Event: Aircraft structural failure Injuries: 2 Fatal
Flight Conducted Under: Part 91: General aviation - Instructional

Analysis: The flight instructor and student were conducting a local area discovery flight in the weightshift-control light sport aircraft. An onboard video of the accident flight and ADS-B data revealed that about 28 minutes into the flight the aircraft entered a right turn as the flight instructor stated another way for them to lose altitude was to “do spirals.” The aircraft then continued a tight descending right turn, and the descent rate and airspeed rapidly increased to near the aircraft’s maneuvering limitations for both bank angle and airspeed. As the aircraft rolled out of the right turn and near a wings-level attitude, three of the battens connecting the left-wing fabric to the wing structure released at the trailing edge. The left wing subsequently began to flutter, and the aircraft rapidly rolled left and entered a spiral dive, from which the pilot was unable to recover before impact with terrain.

A Service Instruction issued by the aircraft manufacturer listed three different factors that can cause the hinged batten to unload: 1) damage to the latch from incorrect loading of the fitting, 2) overtension of the batten within the pocket, and 3) operation outside the placarded limitation of the aircraft. While the investigation was not able to determine the state of battens before the accident, a performance study determined that the aircraft banked near its maximum recommended bank angle of 60° and near its maximum maneuvering speed of 73 kts in a right turn during the descent.

The battens that separated during the flight were not recovered and therefore could not be examined. Postaccident examinations of the airframe and engine revealed no additional evidence of preimpact mechanical malfunctions or failures that would have precluded normal operation. The parachute pin was removed and the parachute was partially deployed. It is likely that the parachute was deployed without enough altitude remaining to fully open and arrest the descent.

Ethanol was detected at low levels in the flight instructor’s liver and muscle tissue specimens collected during a postmortem examination. Some or all of the small amounts of detected ethanol may have been from postmortem production, and it is unlikely that ethanol effects contributed to the crash.

Probable Cause and Findings: The National Transportation Safety Board determines the probable cause(s) of this accident to be -- Structural failure of the wing for undetermined reasons, which resulted in a loss of control. 

FMI: www.ntsb.gov