ERA22LA427

The pilot and passenger were in cruise flight about 3,500 ft mean sea level (msl) flying offshore between 55 and 60 mph in the weight-shift-control (WSC) aircraft. The passenger reported that the pilot informed him that the flight might encounter turbulence, then about 5 minutes later, it felt like, “something punched the plane,” consistent with turbulence. The passenger reported that he then noted 8 of the right wing ribs were extending 3 to 4 inches aft of the aft edge of the wing sail, and the fabric of the right side of the wing was no longer stretched and the right wing area was much smaller than the left wing. He then felt an upward jar, and the aircraft entered a right descending turn that the pilot attempted to control. When “very close to the ocean,” he felt a force consistent with activation of the airframe parachute. After water impact, he struggled but managed to release his restraint and remained in the water about 30 minutes before being rescued. Examination of the wing, which washed ashore several months after the accident, revealed that the outer portion of the sail fabric on the right side of the wing had moved inboard along the leading edge tube and bunched at the juncture of the leading edge tube and wing strut. The inspection did not determine the condition of the ribs on the right side of the wing. The resulting fabric movement, combined with the passenger-reported displacement of multiple wing ribs, likely changed the airfoil shape and lift properties of the right side of the wing, resulting in the right descending turn described by the passenger. Although there was no structural failure of the right wing, it could not be determined why the sail moved inboard along the leading edge tube or what ribs were remaining with the wing and the rib positions among the sail. While the passenger reported experiencing turbulence immediately before the observed wing issue, the available weather data did not support conditions conducive to turbulence, and no cumulus clouds were visible on satellite images or in the dataset around the accident time. Additionally, the passenger’s description of the airframe parachute activation occurring “very close” to the surface of the water suggested that it may not have been activated with sufficient time to fully realize the benefits of such a system.

Review of maintenance records revealed that a new Northwing GT5 13.5m wing was installed on the aircraft in November 2016. Since installation, other than wing removal for other maintenance, there was no record of any repair to the wing in the maintenance records. The Northwing GT5 13.5m wing was a strutted wing and the wing sail was equipped with rib pockets for installation of 12 removable aluminum lower ribs and 24 removable aluminum top ribs, or 6 removable lower ribs and 12 removable top ribs in each side. The lower ribs in the forward section of the wing were straight and held in place by the pocket, while the top ribs, which provided the wing camber in the aft section of the wing, were secured by either string or a flip tip at the trailing edge of the sail. According to the Wing Manual, the wing sail was designed to be retained to the wing structure at the leading edge tip by a sail strap positioned over the end of the trim tip cap and then fitted in a slot or groove. The aircraft manufacturer reported that the only way for the sail to move inboard along the leading edge tube would be if the sail strap was not installed properly over the tip cap. The aircraft was equipped with a portable GPS receiver, a cellular phone, and an iPad. The track log record mode of the GPS receiver was off, but there were two logged flights on the accident date. The last logged flight duration was 0.4 hour, and the distance travelled was about 24 miles. The cellular phone and iPad were damaged; therefore, no data pertinent to the accident were recovered. The pilot’s stepson reported his stepfather flew the aircraft the day before the accident for about 3 hours and there were no reported issues. On September 21, 2022, about 1000 eastern daylight time, a Northwing Design WSC aircraft, N3283N, was substantially damaged when it was involved in an accident near Southern Shores, North Carolina. The private pilot was fatally injured and the passenger sustained minor injuries. The aircraft was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The passenger stated that after arrival at the airport, he read the checklist while his stepfather (the pilot) assembled the aircraft. He followed behind his stepfather and checked everything again. The flight departed between 0830 and 0900 from First Flight Airport, Kill Devil Hills, North Carolina, and flew north along the coast. After flying north about 21 nautical miles, the pilot twice orbited a house, then proceeded south just offshore to return to the departure airport. While enroute, the pilot mentioned that the flight might encounter turbulence; about 5 minutes later, while flying about 400 yards offshore at 3,500 ft mean sea level between 55 and 60 mph, with a “little patch of clouds, very small” below them, it felt like “something punched the plane” consistent with turbulence. He reported that after the turbulence encounter, he noted 8 ribs sticking out 3 to 4 inches beyond the aft end of theright side wing. He also stated that the fabric on right side wing “did not appear tight,” adding that the right side of the wing was much smaller than the left side of the wing. He felt an upward jar, then the aircraft was out of control. It started spiraling to the right, and while descending, the pilot attempted to control the aircraft. When “very close to the ocean,” he felt a force consistent with activation of the airframe parachute. After water impact, he struggled but managed to release his restraint and remained in the water about 30 minutes before being rescued. The passenger further reported that the engine, “never missed a beat” during the flight. An external examination of the pilot was conducted by the Office of the Chief Medical Examiner, Raleigh, North Carolina. The probable cause of death was reported to be blunt force injuries. Toxicology testing performed by the FAA’s Forensic Sciences Laboratory on the pilot’s submitted specimens identified no evidence of impairing drugs. Review of available weather data for the day of the accident did not indicate conditions conducive to turbulence, and no cumulus clouds were visible on satellite images or in the dataset around the accident time. The pilot held a private pilot certificate with ratings for airplane single-engine land and rotorcraft-helicopter. He held a second-class medical certificate with a limitation to have available glasses for near vision issued March 16, 2022. Federal Aviation Administration (FAA) records for the pilot contained FAA Form 8710-11, Airman Certificate and/or Rating Application – Sport Pilot, dated August 20, 2022. On the application, the blocks “Sport,” “Proficiency Check,” and “Weight Shift Control” were checked. The pilot indicated his total time and instruction received in WSC aircraft was 22.9 hours, while he also indicated having 5 hours solo and as pilot-in-command in WSC aircraft. The form was subsequently returned to the instructor for correction, but a corrected form was not received by the FAA. An entry in the pilot’s logbook dated August 20, 2022, specified the flight duration as 1.1 hours and the remarks section indicated, “proficiency – transition to WSC” aircraft. Between that date and the last logged flight on September 16, 2022, the pilot recorded an additional 3.8 hours flight experience in the accident aircraft. The main wreckage, which comprised the lower root tube with attached engine assembly, attached propeller with fractured blades, and fuel tank, washed ashore south of the accident site and was first spotted on October 5, 2022. No structural components of the wing were recovered at that time. The wing was subsequently recovered at a much later date. Inspection of the wing by a Federal Aviation Administration airworthiness inspector revealed that the outer portion of the right side sail had moved inboard along the leading edge tube and bunched up against the leading edge tube at the strut attachment juncture. The inspector did notsee any evidence of structural failure of the outer portion of the right wing, but was unable to determine the reason why the sail moved inboard and did not report the condition of the lower or upper ribs on the right side of the wing. Examination of the propeller revealed that all three blades were fractured at varying lengths. The engine was not examined, as the passenger reported no discrepancies with the engine during the flight.