Accident Sequence
On January 7, 2023, at about 1318 Pacific standard time, a Challenger II light sport airplane, N528J, was substantially damaged when it struck a storage facility near Kent, Washington. The commercial pilot and a pilot-rated passenger were seriously injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
The pilot, seated in the forward seat, reported that a thorough preflight inspection was performed before departure. Shortly after takeoff, while attempting a left turn, the airplane did not respond to left stick inputs. The pilot declared an emergency with the tower controller at Renton Municipal Airport. He reported that the airplane then entered an uncontrolled right turn that intensified. After reducing power, the airplane collided with a storage unit.
The passenger-owner, in the rear seat, stated that he met the pilot for the first time that day. The pilot mentioned he ferries airplanes for a living and, despite no experience in this make and model, he had flown joystick aircraft before and was confident. The passenger noted the airplane had not been inspected and left the airworthiness decision to the pilot. The passenger said the airplane had been on the ramp for weeks and required a thorough preflight. After arriving, the passenger released tie-downs and removed the engine cover while the pilot conducted the preflight, which the passenger described as quick.
Before departure, the passenger explained the flaperon system to the pilot. The pilot departed with flaperons neutral. At about 20 feet above ground level (agl), the airplane veered right. The pilot continued climbing, and at about 600 ft agl, he told the passenger the ailerons were not responding properly and were locking up. He radioed that he would return to the airport. The passenger confirmed his rear seat controls were clear. The pilot then radioed that they would crash into a storage facility.
A video from the passenger showed the right side of the airplane taxiing and departing. The runway was wet from rain, and the sky was overcast. Shortly after departure, the airplane banked right and recovered at about 20 ft agl. The engine sound was smooth at various rpm settings.
ADS-B data showed the airplane departing north, entering a slight right turn, then making a sharp right 270° turn west, followed by multiple descending right turns over the accident site.
Two security videos captured the airplane in a nose-down, right-wing-low attitude before impacting the roofs of two storage buildings.
The 1328 recorded weather observation at Renton Municipal Airport included calm wind, light rain, 5 statute miles visibility, a broken ceiling at 4,800 ft agl, and an overcast ceiling at 6,000 ft agl.
Aircraft and Flight Crew Information
The pilot reported 650 total flight hours and no experience in the accident airplane make and model.
The Challenger II (Quad City Challenger II) is a two-seat, strut-braced high-wing monoplane with a Rotax 503 pusher engine and a three-bladed ground-adjustable propeller. Lateral roll control is via flaperons. It has a fixed tricycle landing gear with an additional tailwheel. The airplane was manufactured in 2017.
The airplane owner's manual describes flaperon functions: they decrease stall speed for shorter takeoffs and landings and provide adjustable pitch trim. It warns that at high speeds, full flaperons can create extremely heavy stick forces, and if combined with high power, the dive may become unrecoverable until power is reduced or flaperons raised. Proper center of gravity (CG) setting, with pilot weight in the front seat, is emphasized for comfortable flight without flaperons. The manual's opening paragraph states that under no circumstances should anyone fly without a proper checkout.
Wreckage and Systems Examination
An FAA inspector examined the accident site. The airplane came to rest on a storage facility roof, with substantial damage to both wings and the fuselage. The flaperon system worked normally when tested from the cockpit crank handle. A photo taken before the examination showed the flaperons near the full-down position.
Wreckage examination revealed impact damage. The forward control stick aileron cables had separated at the left aileron turnbuckle and the right aileron cable near the forward pulley. Cable sections were sent to the NTSB Materials Laboratory, where fractures were found consistent with overload. Cable contact marks were present on left pulley grooves and brackets, but no abnormal marks on the right side. The remaining flight control system was intact. The aft support structure and engine were crushed forward. The idler pulley control cable was loose from its assembly. The engine showed no evidence of preimpact mechanical malfunctions that would have precluded normal operation.
Due to insufficient information gathered during the investigation, a CG determination was not performed for the accident flight.