N528J

On January 7, 2023, about 1318 Pacific standard time, a Challenger II light sport airplane, N528J, was substantially damaged when it was involved in an accident near Kent, Washington. The commercial pilot and pilot-rated passenger sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

The airplane was recently purchased by the pilot-rated passenger, who hired the pilot to fly the airplane from Auburn Municipal Airport (S50), Auburn, Washington, to Harvey Field Airport (S43), Snohomish, Washington. The pilot, who was seated in the forward seat, reported that “a thorough preflight inspection was conducted” before departure. Shortly after departing, the pilot attempted a left turn and noted that the airplane was unresponsive to left stick inputs. The pilot declared an emergency with the tower controller at Renton Municipal Airport (RNT), Renton, Washington. He reported that the airplane then entered an “uncontrolled” turn to the right that increased in intensity. He reduced power, and the airplane impacted a storage unit.

The passenger/owner, who was seated in the rear seat, reported that he met the pilot for the first time the day of the accident. The pilot stated to him that he ferries airplanes for a living and although he had no previous experience in this airplane’s make and model, he had flown joystick aircraft before and was confident with no hesitations. The passenger stated to the pilot that the airplane had not been inspected and that the pilot would make the final call on whether the airplane was airworthy for the upcoming ferry flight. He further stated to the pilot that the airplane had been sitting on the ramp for weeks and needed a thorough preflight inspection. After arriving at the airplane, the passenger told the pilot that he would release the tie downs and remove the cover from the engine while the pilot conducted the preflight inspection. The passenger reported that the pilot did a quick preflight inspection and soon assisted him in releasing the rest of the tie downs.

Before departure, the passenger described the flaperon system to the pilot. The pilot departed with the flaperons in the neutral position, and at about 20 ft above ground level (agl), the airplane veered to the right. The pilot continued to climb out, and at about 600 ft agl, the pilot stated to the passenger that the ailerons were not responding properly, and they were getting locked up. He then reported over the radio that he was going to return to the airport. The passenger responded to the pilot that his rear seat controls were clear. The pilot then reported over the radio that they were going to crash into a storage facility.

A video from the passenger showed a view of the right side of the airplane taxiing to and departing from the runway. The runway was wet from rain and the sky was overcast. Soon after the airplane departed the runway, the airplane banked to the right and recovered at about 20 ft agl. The engine sound was smooth at various rpm settings.

ADS-B data showed the airplane depart to the north and enter a slight right turn. Soon after, the track displayed a sharp right 270° turn toward the west. Shortly thereafter, the airplane made multiple descending right turns over the accident site location.

Two security videos from the storage facility captured the airplane while it was in a nose-down, right-wing-low attitude before impacting the roofs of two storage buildings.

The 1328 recorded weather observation at RNT 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.

The pilot reported 650 total hours of flight experience. He reported no experience in the accident airplane make and model.

The Challenger II, also called the Quad City Challenger II, is a two-seat, strut-braced high-wing monoplane of simple design, with a Rotax 503 engine mounted in a pusher configuration, which is equipped with a three-bladed, ground-adjustable propeller. Lateral roll control is achieved using flaperons. The aircraft has a fixed tricycle undercarriage, but also features a small tailwheel to protect the tail when the aircraft is unoccupied. The airplane was manufactured in 2017.

A Federal Aviation Administration (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 from the crank handle in the cockpit. A photo of the wreckage on the roof before the FAA examination showed the flaperons near the full-down position.

Examination of the wreckage revealed impact damage to the airframe and both wings. The forward control stick aileron cables separated at the left aileron turnbuckle and right aileron cable near the forward pulley. The forward control stick aileron cable sections, including turnbuckles and forward pulleys, were removed and sent to the NTSB Materials Laboratory for further examination. The examination revealed fractures consistent with overload. Cable contact marks were also visible on the left pulley grooves and on the left cable pulley brackets. No abnormal cable contact marks or scratches were observed on the right pulley or the right pulley attachment brackets. The remaining flight control system was intact. The aft support structure and engine were crushed forward. The idler pulley control cable was found loose from the pulley assembly. Postaccident examination of the engine revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation.

The airplane owner’s manual stated:

The flaperons on the Challenger serve two functions. They decrease stall speed to help shorten landings and takeoffs. They also provide adjustable pitch trim. The overall range of their travel can be adjusted to suit the (front seat) weight of the owner by lengthening or shortening the aileron pushrods. Typically, from the full up position the first several turns of the crank will provide pitch trim for the full speed range of the Challenger.

Be aware that the use of flaperons will make for increased stick pressures which you will need to resist to maintain a constant approach speed. Also be aware that at high speeds, the use of full flaperons can create an extremely heavy stick condition as the increased airflow increases the pitch down effect of the flaperons.

If through inattention, while using full flaperons, a high or full power condition also exists (further increasing the nose down tendency and airspeed) and the speed is allowed to develop excessively, it can reach a point where it becomes impossible to resist the stick pressure and increasingly steep dive will result. Reducing the power to idle and/or raising the flaperons will immediately correct the situation.

According to the flight manual, if you are slightly nose heavy, you will have to fly with the ailerons or flaperons in a more up (reflex) position. If you are slightly tail heavy, you will have to fly with the ailerons or flaperons in a more down (flap) position. Adjust your aileron pushrods accordingly. Elevator trim tabs may also be used (tab down for nose up trim).

According to the airplane manufacturer, for comfortable straight-and-level flight characteristics without the use of flaperons, the center of gravity (CG) needs to be properly set up. This is determined with the weight of the pilot in the front seat location and where the datum is positioned when determining proper CG. Due to the lack of information gathered during the investigation, a CG was not completed for the accident flight.

The opening paragraph of the owner’s manual stated:

Under no circumstances, regardless of experience level, should you consider flying without a proper checkout…Accidents have occurred when pilots have performed first flights without a type checkout.