Endicott, NY, USA
N450C
Trella T-21
According to a witness, the pilot of the experimental, amateur-built airplane had completed one takeoff and landing in the airport traffic pattern. Following the second takeoff, at an altitude about 300 ft above ground level, the witness heard the engine "pop." The airplane remained in a nose-high attitude as it entered a steep left turn as if to return toward the runway; the witness stated that the airplane then spiraled toward the ground. Another witness stated that he heard the accident airplane's engine power decrease as it climbed through about 300 ft after takeoff and the airplane subsequently entered a descending left turn before disappearing behind trees. Postaccident examination of the engine revealed no mechanical anomalies that would have precluded normal operation, and there was no evidence of fuel contamination. All major components of the airplane were located at the accident site, and flight control continuity was established from the cockpit to all flight control surfaces. Review of the airplane's logbook and a witness account indicated that, about 1 year before the accident, the pilot had experienced aerodynamic flutter of the rudders on at least two occasions and made subsequent airframe modifications as a result; however, there was no evidence to indicate that this contributed to the accident. The airplane's steep descent before impact and the limited wreckage distribution at the accident site were consistent with an aerodynamic stall/spin. It is possible that the pilot may have experienced a partial loss of engine power or other engine anomaly (based on the witness statements) and, in response, attempted to complete a 180° turn back to the runway. During the turn, the pilot exceeded the airplane's critical angle of attack, which resulted in an aerodynamic stall/spin and a loss of control. The reason for the loss of engine power could not be determined.
HISTORY OF FLIGHT On June 17, 2019, about 1125 eastern daylight time, an experimental Trella T-21, N450C, was substantially damaged when it was involved in an accident near Endicott, New York. The commercial pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. A witness stated that the pilot's first takeoff and landing appeared normal. During the second takeoff, he witnessed the airplane climb out normally until it was just past the runway 21 threshold about 300 ft above ground level and the engine made a loud single “pop” similar to a backfire. The airplane remained in a slightly nose-high attitude as it began a left turn almost immediately following the “pop.” The turn looked to begin at a normal rate and bank angle but quickly steepened and became tighter. As the airplane's bank angle reached around 60 to 70°, the nose began to fall and the airplane spiraled to the ground. The airport manager stated that he heard a reduction in the airplane's engine power as the airplane was about 300 ft above the runway. He then watched the airplane continue toward the end of the runway, where it entered a left descending turn before disappearing behind trees (Figure 1 shows the accident site location in relation to the airport). Figure 1. Accident site location. AIRCRAFT INFORMATION The airplane was a high wing, all-metal construction, two-place airplane with twin tailbooms and a pusher engine configuration. The airplane was originally equipped with a Continental C-85-12J engine, which generated 85 horsepower (hp). As originally certificated, the airplane had a maximum gross weight of 1,550 lbs and a maximum speed of 112 mph. The airplane was issued an experimental, amateur-built airworthiness certificate in June 1957. In September 1964, a 125-hp Lycoming O-290-11(D) engine was installed at an airframe time of 314.5 hours. The accident pilot purchased the airplane with an unknown total time in June 2014. The airplane logbook indicated that the pilot completed extensive work on the airplane between June 2014 and June 2017, which included installing a 160-hp Lycoming O-320 engine and a Sensenich wooden propeller. The logbook indicated that the airplane was re-assembled in March 2017 with new paint and all new hardware. The flight controls were rigged, and all the cables were tensioned. The pilot endorsed the airplane as airworthy on June 1, 2017, and several flights were annotated in the logbook between June 15, 2017, and September 18, 2018, totaling 15.9 hours. An entry on July 4, 2017 stated that, during high speed tests, the airplane “experienced rudder flutter at 110 mph.” A subsequent entry stated, “Removed rudders, designed and built balance weight brackets. Balanced both rudders at 100%. Balanced elevator at 100%. Reinforced tail booms. Retensioned rudder & 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 of flight time were logged after the June 21, 2018, test. A notebook found in the airplane at the accident site listed a total flight time of 3.7 hours between May 4 and June 7, 2019. One of the witnesses of the accident recalled seeing the accident pilot land the accident airplane in June or July 2018. The airplane made a "skidding, very flat, continuous turn from downwind to final" as it approached the runway, the rudders seemed to be "deflecting stop to stop," and the tail of the airplane was "wagging back and forth quite noticeably." The witness then drove to the airport, where he found the pilot putting the airplane into its hangar. The pilot stated that he "knew how to fix" the flutter and the witness assumed that the pilot had done so, as he had seen the airplane fly "many times since" and did not witness the flutter again. WRECKAGE AND IMPACT INFORMATION The airplane was mostly intact but exhibited multiple areas of crush and compression damage. Both wings remained attached to the fuselage at their normal mounting locations. All components of the airplane were in the vicinity of the main wreckage. Rudder, elevator, and aileron control continuity was established from the flight control surfaces to their respective cockpit controls. The throttle control was extended aft about 1 inch from the fully-closed (idle power) position and the throttle shaft handle was bent about 90°. The mixture control was found in the full-rich position. The twin tailbooms remained attached to the wings. Both tailbooms were partially fractured and deformed to the right. Both vertical stabilizers were deformed to the left near the aft end of the tailbooms and both rudders were deflected full left. The lower portions of both vertical stabilizers and rudders were crushed upward. The right tailboom was partially fractured near the wing trailing edge and deformed downward at the location of an unpainted doubler. The horizontal stabilizer and elevator, which were installed between the two vertical stabilizers, remained intact and exhibited some upward deformation about mid-span. The engine remained attached to the firewall and its mount. Most of the engine mount was fractured from impact damage. The propeller remained attached to the engine crankshaft, but the blades were fractured and splintered with most of the blades missing. All engine accessories were found attached to the engine except for the carburetor float bowl, which had impact damage and was separated from the carburetor throttle body at the mating surface. Impact damage was noted on all the exhaust tubes. The engine was rotated by hand at the propeller hub. Crankshaft continuity and thumb compression were confirmed on all four cylinders. A lighted borescope inspection of the cylinders revealed no anomalies. The sparkplugs were removed and no damage was observed. Sparkplug coloration was consistent with normal engine operation when compared to the Champion Check-A-Plug chart. The oil pressure screen was unobstructed. The carburetor fuel inlet screen exhibited some debris but was not obstructed. The electric fuel pump was disassembled and its screen was free and clear of any contamination. The gascolator screen was free of debris. Fuel from onboard the airplane was tested for water contamination and none was found. Fuel from the airport's facility was tested and also revealed no evidence of water contamination. Figure 2 shows the airplane wreckage from aft looking forward. Figure 2. Airplane wreckage from aft looking forward. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy of the pilot was performed at the Department of Laboratory Medicine, Wilson Regional Medical Center, Johnson City, New York. The pilot's cause of death was multiple blunt force injuries. Toxicology testing performed at the Federal Aviation Administration Forensic Sciences Laboratory was positive for losartan and amlodipine and was negative for ethanol. Both carbon monoxide and cyanide tests were not performed. Losartran and amlodipine are prescription medications that treat high blood pressure and are not considered impairing.
A partial loss of engine power for reasons that could not be determined, and the pilot's subsequent exceedance of the airplane's critical angle of attack during an attempted return to the runway, which resulted in an aerodynamic stall/spin at an altitude that precluded recovery.
Source: NTSB Aviation Accident Database
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