ANC25LA008

On November 2, 2024, about 1436 Alaska daylight time, a Cub Crafters CC18-180 airplane, N55PK, sustained substantial damage when it was involved in an accident at the Lake Hood Airport (LHD) Anchorage, Alaska. The pilot was seriously injured. The airplane was operated as a public aircraft flight. The accident airplane was owned by the U.S. Department of the Interior and operated by the National Park Service. The purpose of the flight was to reposition the airplane back to Fairbanks, Alaska, where the pilot and airplane were based. The airplane departed from runway 32 at LHD. The pilot reported that, after the airplane became airborne, he was unable to move the flight control stick forward and the airplane started climbing aggressively. The pilot attempted to use the elevator trim control to lower the nose and level the airplane. However, the airplane stalled and began an uncontrolled, nose-down descent toward the runway. The pilot was able to level the airplane slightly but there was insufficient altitude to recover from the stall. The airplane impacted the runway and came to rest about 78 ft from the initial impact site, resulting in substantial damage to the fuselage and both wing lift struts. A postaccident examination revealed that the rear flight control stick was incorrectly installed. The flight control stick was installed in reverse. The curve of the control stick was curved forward; the control stick would contact the pilot’s seatback, which restricted movement and limited the control stick from moving forward. The pilot’s front seat was found in the full aft and locked position. It was the operator’s practice that pilots could remove the aft control stick when they were flying cargo so that the cargo wouldn’t interfere with the control stick. The accident pilot reported that he had never removed the rear control stick in the airplane, nor had he received training on how to remove or install the rear flight control stick. The pilot was unaware that the rear flight control stick could be installed incorrectly. The pilot had always flown with an instructor pilot in the rear seat. The pilot did not know who installed the rear control stick before his flight, and the subsequent accident investigation was unable to identify who installed it incorrectly. The pilot stated that he performed a preflight inspection and found no discrepancies. The rear control stick was already installed when he arrived. The weight and balance was calculated to be within limits. He then taxied the airplane to Runway 32 for departure. He said, in part: ”I did one last carburetor heat check and one last control check and then got clearance from the tower for takeoff.” A postaccident reenactment of the flight control check and takeoff was conducted in an exemplary CC18 in the Office of Aviation Services hangar. The front seat was positioned in the aft position and the rear control stick was installed backward. The flight control check appeared normal with no binding.After applying backstick pressure to simulate the takeoff, forward pressure was applied, and the control stick became jammed in the forward position and was unmovable in any direction until the pilot leaned forward and the stick released. During the reenactment, the control stick became jammed with the front seatback frame. Cub Crafters’ supplement dated January 13, 2016, which describes the process and requirements for reinstalling the rear control stick, states in part: “Ensure full range of motion (including trim) is met without the rear stick contacting anything.” Additionally, the supplement must be added to the pilot’s operating handbook and the Federal Aviation Administration approved flight manual when the rear control stick is removed and reinstalled. As a result of this investigation, the U.S. Department of the Interior issued a safety alert (DOI SA 25-01) dated November 15, 2024, to address the correct installation of the rear flight control stick. Additionally, the safety alert highlights the preflight and before takeoff checklists requiring flight control checks to verify the maximum range of travel is available.