Accident Summary
On November 10, 2013, at 0843 Central Standard Time, an experimental amateur-built RANS S-12XL, registration N933CW, was substantially damaged during a forced landing near Gordon, Alabama. The sport pilot and his passenger were uninjured. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight conducted under 14 CFR Part 91. The flight departed from a private turf airstrip near Gordon, Alabama, destined for a private airstrip in Ashford, Alabama.
Pilot Information
According to Federal Aviation Administration (FAA) and pilot records, the pilot held a sport pilot certificate and repairman certificates for the RANS S-12 and S-14. He reported a total of 2,000 hours of flight time, with 221.9 hours in the accident airplane make and model.
Aircraft Information
The accident airplane was a high-wing, pusher-configured monoplane. The cockpit area was constructed of welded 4130 steel tubing, the rear fuselage of bolted 6061-T6 aluminum tubing, and the wings of aluminum tubing and ribs. The fuselage, wings, and tail surfaces were covered in Dacron fabric. The airplane was equipped with wing-mounted flaps and tricycle landing gear, powered by a 100-horsepower Rotax 912 ULS engine driving a Warp Drive 3-bladed carbon fiber propeller. It received its experimental airworthiness certificate in 2002, and its last conditional inspection was completed on August 3, 2012. At the time of the accident, the airplane had accrued 221.9 total hours of operation.
Meteorological Information
The reported weather at Dothan Regional Airport (DHN), Dothan, Alabama, located 21 nautical miles northwest of the accident site, at 0853 recorded: wind 100 degrees at 3 knots, visibility 10 miles, clear sky, temperature 17°C, dew point 7°C, and an altimeter setting of 30.38 inches of mercury.
Wreckage Examination
Post-accident examination by an FAA inspector revealed that the nose wheel landing gear assembly had collapsed, the forward fuselage structure tubing was substantially damaged, and one of the three propeller blades was broken. Control continuity for the control surfaces was established to the cockpit, but the cable that actuated the elevator trim tab was found fractured.
Trim System Examination
The RANS Mechanical Trim Tab System featured a trim tab actuated by a push-pull wire, known as the "trim push wire." Examination showed the wire was not braided but of solid core design. It rode inside a trim cable housing until it reached the right elevator trailing edge spar, where it exited and was secured to the trim tab by a wire swivel/screw stop attached to the trim horn. The trim push wire was found bent and fractured just forward of the wire swivel/screw stop. Examination of the fractured end revealed corrosion and striations indicative of fatigue. Examination of the trim horn faces showed wear, scratching, and gouging, indicating that the wire swivel/screw stop had been binding and unable to rotate under load.
Manufacturer's Alert
Photographs of the fractured trim push wire were forwarded to the airplane manufacturer, who also believed the fractured face indicated a fatigue failure. The manufacturer noted a similar failure observed when spectators at an airshow leaned against a trim tab, bending the wire, which later failed in flight. On May 24, 2013, RANS Design Inc. issued Operational Alert 173 (OA-173), requiring mandatory compliance for all models using a push-pull wire trim system. The alert recommended inspecting the wire termination during preflight, ensuring the wire swivel pivots freely, replacing suspect or bent wire with proper spec wire, and considering installation of an electric trim servo.