History of Flight
On May 22, 2014, about 1830 central daylight time, a special light sport P&M Aviation QuikR weight shift aircraft, N428PM, was substantially damaged at Jack Edwards National Airport (JKA), Gulf Shores, Alabama. The airline transport pilot sustained serious injuries. Visual meteorological conditions prevailed for the personal flight and no flight plan was filed for the local flight. The flight was conducted under 14 CFR Part 91.
According to the pilot's written statement, he performed a preflight inspection and then attempted to start the engine in an area surrounded by hangars. He applied full choke, set the hand throttle to idle, applied full left foot brake, and placed the magnetos in the ON position. After about four unsuccessful attempts, the pilot moved the choke back and forth, leaving it about halfway. He introduced a "little bit of right foot throttle" and, after about four more attempts, the engine started and "immediately" advanced to "takeoff power." The pilot applied full left foot brake, but the aircraft moved forward at increasing speed. He attempted to steer the nose wheel to maintain the taxiway centerline, while holding the control bar with his left hand and groping for the magneto cutoff with his right hand. He eventually disengaged one magneto, but the right wing of the aircraft impacted the cowling of a parked airplane located to the right of the taxiway centerline. The aircraft spun to the right, impacted a hangar door, and came to rest.
Postaccident examination by a Federal Aviation Administration (FAA) inspector revealed damage to the left wing spar. The parked airplane sustained damage to its propeller and nose cowling. Further examination of the engine control system showed that the foot pedal throttle and hand throttle both operated smoothly with no binding.
Personnel and Aircraft Information
The pilot held an airline transport certificate with ratings for airplane single and multiengine land. He had accumulated about 12,737 total flight hours, with 72 hours in the accident airplane make and model.
The accident airplane was manufactured in 2009. It was a special light sport weight-shift-control category aircraft equipped with a three-bladed Warp Drive propeller and one Rotax 912ULS four-stroke engine rated at 100 horsepower. The most recent condition inspection was completed on April 1, 2014, at which time the airplane had 179.1 total flight hours.
Throttle System
The airplane was equipped with a foot throttle that automatically returned to the CLOSED position (similar to an automobile accelerator) and a friction-dampened hand throttle. It also had a starter motor solenoid interrupt switch that prevented engine starting with the hand throttle engaged. Throttle cables connected to a splitter containing a single piston designed to open and close butterfly valves on both carburetors. The carburetors were originally designed by the engine manufacturer to default open if a cable severed, but were altered by the airframe manufacturer to spring-shut.
Wreckage and Impact Information
The initial impact point was the cowling of a parked airplane about 150 feet from the accident pilot's hangar. The left wing spar was broken, with torn cloth on the left wing and top center sail. All flight control surfaces remained attached, and continuity was traced. All three carbon fiber propeller blades separated: blade A outboard, blade B mid-span, and blade C inboard near the hub.
Further examination in a secure hangar by the airframe manufacturer's representative under FAA supervision found the engine case undamaged and free of leaks. The right foot throttle pedal was operated several times, showing some abnormal friction, but both carburetors opened and closed each time. The hand throttle was advanced and retarded multiple times, and during each operation the hand throttle interrupt switch could be heard, indicating the solenoid was engaging. The hand choke functioned normally with no binding.
However, the foot throttle cable extended from the right foot pedal behind a pod support bracket and along the basetube. Postaccident examination revealed two snag hazards that could cause the foot throttle to remain open. In one instance, when depressed, the throttle cable could be manipulated by hand to snag on a bolt fastening the pod support bracket to the fuselage. In another, the cable could snag on the pilot's left foot, unseating the cable end and causing the throttle to stick open.
Starting Instructions
The manufacturer's operating instructions, section "6.3 Starting Engine," stated: The pilot must always start the engine when sitting in the cockpit with seatbelts secured and helmet worn. Pre-start checks included ensuring both throttles are working and fully shut (never use the hand throttle for engine control on the ground). If a starter interrupt switch is fitted, the starter will not operate unless the hand throttle is CLOSED. Warnings emphasized engine start as a potentially dangerous time and advised ensuring the aircraft points away from people, vehicles, buildings, and that the area is clear before starting.