NTSB Factual Report

On May 31, 2008, about 1115 Pacific daylight time, an experimental light sport airplane (ELSA) Quad City Ultralight Aircraft Challenger LSS, N95478, impacted a field near Moses Lake Municipal Airport, Moses Lake, Washington. The pilot/owner was operating the airplane under the provisions of 14 CFR Part 91. The light sport pilot, the sole occupant, was killed; the airplane sustained substantial damage. The personal local area flight departed from Moses Lake, about 0945. Visual meteorological conditions prevailed, and a flight plan had not been filed.

In a telephone conversation with a National Transportation Safety Board investigator, a witness reported that he assisted the pilot in the building of the accident airplane. He stated that he was washing the airplane when the pilot arrived at the airport. The pilot seemed happy and eager to fly the airplane, as he had only amassed about 10 hours in the airplane and was planning a flight across the United States. After fueling the airplane with full tanks (about 16.5 gallons), the witness observed the pilot start the airplane and eventually taxi to the active runway. Following a run-up, the pilot departed. The pilot had planned to circle the airplane over a friend's house and then perform practice touch-and-go takeoff and landings in Quincy, Washington.

The witness further stated that about 1 hour 20 minutes after the airplane departed, he heard the pilot transmit over the common frequency that he was about 5 to 10 miles southwest of the town. He then reported that he was on the 45-degree interception to the downwind leg of the traffic pattern for runway 16. The witness noted the pilot originally transmitted that he was in a "Bonanza," then quickly corrected to indicate that he was in an "experimental." The witness queried the pilot over the radio as to how many landings he made in Quincy, to which he replied "two."

The witness reported that as the airplane was on the downwind leg and almost abeam the runway identifier numbers, the engine power seemed to reduce and the nose pitched up about 15 degrees. The airplane made a tight turn onto the base leg and then overshot final approach, which started about .25 to .5 miles from the approach end of the runway. The airplane was high and appeared to be configured in a slip (right wing low) while approaching the runway. When reaching about 30 feet above ground level (agl), the airplane pitched nose high, as if the pilot was attempting to flare. The witness immediately transmitted over the radio for the pilot to "go around," as he was fearful the airplane would stall. The engine power slowly increased and the airplane turned about 45 degrees and barely cleared a hangar and power lines on the departure from the aborted landing.

The witness then observed the airplane make numerous erratic maneuvers, while varying altitudes between 45 to 300 feet agl. He transmitted calls over the radio, but the pilot failed to respond. The airplane temporarily continued in level flight and then began more erratic turns. The airplane then pitched up about 65 degrees nose-high and made a left bank. It subsequently stalled and continued in a spin about 360 degrees before impacting a field located adjacent to the runway.

Following the accident, the wreckage was examined by three Federal Aviation Administration (FAA) certified mechanics that additionally held their inspection authorizations (IA). In a written statement, one of the mechanics reported that they noticed that the vertical fin was not secured to the fuselage, as it remained only attached to the airplane by the horizontal tail plane struts, the elevator control pushrods, and the rudder cables. Further examination revealed 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 to the fuselage were secured to the fuselage tubing, but not to the vertical fin tubes. The undrilled vertical fin attach tubing appeared to be resting on top of the bolts. A complete pictorial diagram is contained in the public docket for this accident.

The Quad City Challenger LSS Build Manual for the accident airplane, Section III, "Fuselage", contains a section named, "How to install the tail section and dorsal fin." Under the heading it provides a picture of the attach tubing and states "Remove AN-4-15A bolt shipped with fuselage." It continues by instructing the builder to "Insert vertical fin into tail posts," and then to "Drill through [the] bolt hole with 1/4" bit and re-install bolt and nyloc."

The FAA Bioaeronautical Sciences Research Laboratory performed toxicological testing of specimens of the pilot. The results of analysis of the specimens were negative for carbon monoxide, cyanide, ethanol, and tested drugs.

NTSB Probable Cause

The pilot's inability to maintain control due to an in-flight separation of the vertical fin as a result of the failure of the airplane's builder to properly secure the vertical fin to the fuselage.