History of Flight
Witnesses observed the pilot perform a normal first takeoff and landing. During the second takeoff, as the airplane climbed past the runway 21 threshold at about 300 feet above ground level, the engine produced a loud single "pop" similar to a backfire. The airplane, maintaining a slightly nose-high attitude, initiated a left turn almost immediately. The turn initially appeared normal but quickly steepened, reaching a bank angle of 60 to 70°, at which point the nose dropped and the airplane spiraled into the ground.
The airport manager reported hearing a reduction in engine power when the airplane was about 300 feet above the runway. He then observed the airplane continue toward the end of the runway, enter a left descending turn, and disappear behind trees.
Aircraft Information
The accident airplane was an experimental Trella T-21, registration N450C, constructed as an amateur-built, high-wing, all-metal, two-place aircraft with twin tailbooms and a pusher engine configuration. It was originally equipped with a Continental C-85-12J engine (85 horsepower). The airplane received an experimental airworthiness certificate in June 1957. In September 1964, at an airframe time of 314.5 hours, a 125-horsepower Lycoming O-290-11(D) engine was installed.
The pilot purchased the airplane in June 2014 with unknown total time. Between June 2014 and June 2017, extensive work was completed, including installation of a 160-horsepower Lycoming O-320 engine and a Sensenich wooden propeller. The airplane was re-assembled in March 2017. The pilot endorsed it as airworthy on June 1, 2017. Logbook entries recorded 15.9 hours of flight between June 15, 2017, and September 18, 2018.
An entry on July 4, 2017, noted that during high-speed tests the airplane "experienced rudder flutter at 110 mph." Subsequent entries described removal of rudders, design and construction of balance weight brackets, balancing of both rudders and elevator at 100%, reinforcement of tailbooms, and retensioning of rudder and elevator cables. An entry on June 21, 2018, indicated that the airplane was tested at high speed up to 140 mph with no adverse tendencies. An additional 7.5 hours were logged after that test. A notebook found at the accident site listed 3.7 hours of flight between May 4 and June 7, 2019.
A witness recalled observing the accident pilot land the airplane in June or July 2018, describing a "skidding, very flat, continuous turn from downwind to final," with rudders deflecting "stop to stop" and the tail "wagging back and forth quite noticeably." The witness spoke with the pilot, who stated he "knew how to fix" the flutter. The witness later saw the airplane fly many times without observing flutter again.
Wreckage and Impact
The airplane was mostly intact but exhibited multiple areas of crush and compression damage. Both wings remained attached. All components were near the main wreckage. Control continuity for rudder, elevator, and ailerons was established. The throttle control was extended aft about 1 inch from the fully-closed position, and the throttle shaft handle was bent approximately 90°. The mixture control was in the full-rich position.
The twin tailbooms remained attached to the wings, partially fractured and deformed to the right. Both vertical stabilizers were deformed to the left near the aft end, and both rudders were deflected full left. The lower portions of vertical stabilizers and rudders were crushed upward. The right tailboom was partially fractured near the wing trailing edge and deformed downward at an unpainted doubler. The horizontal stabilizer and elevator were intact with upward deformation.
The engine remained attached but most of its mount was fractured from impact. The propeller was attached to the crankshaft, but blades were fractured and splintered. All engine accessories were attached except the carburetor float bowl, which had impact damage and was separated. Engine continuity was confirmed, and thumb compression was present on all cylinders. A borescope inspection revealed no anomalies. Sparkplug coloration was consistent with normal operation. The oil pressure screen was unobstructed. The carburetor fuel inlet screen showed some debris but was not obstructed. The electric fuel pump screen was clear. The gascolator screen was free of debris. Fuel from the airplane and from the airport facility tested negative for water contamination.
Medical and Pathological Information
An autopsy determined the pilot's cause of death as multiple blunt force injuries. Toxicology testing was positive for losartan and amlodipine, prescription medications used to treat high blood pressure that are not considered impairing. Tests for ethanol were negative; carbon monoxide and cyanide tests were not performed.