Accident Overview
On May 31, 2008, about 1115 Pacific daylight time, an experimental light sport airplane (ELSA) Quad City Ultralight Aircraft Challenger LSS, registration N95478, impacted a field near Moses Lake Municipal Airport, Moses Lake, Washington. The pilot, who was the sole occupant, was killed; the airplane sustained substantial damage. The personal local area flight had departed from Moses Lake about 0945. Visual meteorological conditions prevailed, and a flight plan was not filed.
Witness Account
A witness who assisted the pilot in building the accident airplane reported that he was washing the airplane when the pilot arrived at the airport. The pilot appeared happy and eager to fly, having accumulated only about 10 hours in the airplane and planning a cross-country flight. After fueling with full tanks (approximately 16.5 gallons), the witness observed the pilot start the airplane, taxi, perform a run-up, and depart. The pilot planned to circle over a friend's house and then practice touch-and-go landings in Quincy, Washington.
About 1 hour 20 minutes after departure, the witness heard the pilot transmit over the common frequency that he was 5 to 10 miles southwest of the town, then on a 45-degree interception to the downwind leg of the traffic pattern for runway 16. The pilot initially reported being in a "Bonanza" but quickly corrected to "experimental." The witness asked how many landings were made in Quincy, and the pilot replied "two."
As the airplane was on downwind almost abeam the runway numbers, the engine power seemed to reduce, and the nose pitched up about 15 degrees. The airplane made a tight turn onto base, overshot final, and appeared high and in a slip (right wing low) while approaching the runway. At about 30 feet above ground level, the airplane pitched nose-high as if flaring. The witness immediately transmitted "go around" fearing a stall. Engine power slowly increased, and the airplane turned about 45 degrees, barely clearing a hangar and power lines.
Subsequently, the airplane made numerous erratic maneuvers at varying altitudes between 45 and 300 feet above ground level. The witness transmitted calls with no response. The airplane temporarily resumed level flight, then performed more erratic turns, pitched up about 65 degrees nose-high with a left bank, stalled, and spun approximately 360 degrees before impacting a field adjacent to the runway.
Post-Accident Examination
Following the accident, three Federal Aviation Administration (FAA) certified mechanics (holding inspection authorizations) examined the wreckage. They noted that the vertical fin was not secured to the fuselage; it remained attached only by the horizontal tail plane struts, elevator control pushrods, and rudder cables. Further examination showed that the vertical fin attach tubes (forward and aft) had not been secured to the fuselage attach tubing. The bolts designed to secure the vertical fin were fastened to the fuselage tubing but not through the vertical fin tubes. The undrilled vertical fin attach tubing appeared to rest on top of the bolts.
The Quad City Challenger LSS Build Manual includes instructions for installing the tail section. It says to remove a specific bolt, insert the vertical fin into tail posts, drill through the bolt hole with a 1/4-inch bit, and reinstall the bolt with a nyloc nut. The condition of the wreckage indicated that this step was not completed.
Toxicology
The FAA Bioaeronautical Sciences Research Laboratory performed toxicological testing on specimens from the pilot. Results were negative for carbon monoxide, cyanide, ethanol, and tested drugs.