Delta, CO, USA
N427LB
RANS S-12
The pilot of the test flight was attempting to correct airplane stability issues before the flight. A witness assumed that the pilot was planning to perform a high-speed taxi test rather than flight, and that the airplane’s takeoff was unintentional. After takeoff, the airplane was seen in the airport traffic pattern at 300-400 ft above ground level. Witnesses then observed the airplane change pitch and bank while the engine was heard increasing to full power and then decreasing. The airplane stalled, impacted terrain, and was destroyed by impact forces. Post-accident examination of the airplane confirmed flight control and engine continuity. There were four ballast bags (about 25 lbs each) and two dumbbell weights (marked 35 lbs). All the ballast bags and one dumbbell weight were in the passenger seat area. High-speed taxi testing is not a test area of aircraft stability and control. Given the pilot’s previous statement of his intentions and the presence of ballast/weights in the passenger seat area, it is likely that he was experimenting with airplane stability and control when the airplane exceeded its critical angle of attack, which led to an aerodynamic stall.
HISTORY OF FLIGHTOn May 3, 2020, at 1110 mountain daylight time, a Rans S-12 airplane, N427LB, was destroyed when it was involved in an accident near Delta, Colorado. The pilot sustained fatal injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 test flight. A witness stated that he talked to the pilot about the airplane’s stability issues, and the pilot told him that he performed some high-speed taxi tests and was trying to adjust to correct the issues. The witness did not think the pilot was going to fly [on the day of the accident] and was only going to perform another set of high-speed taxi tests. The witness believed the pilot was caught off guard and the airplane became airborne. A witness at Blake Field Airport (AJZ), Delta, Colorado, stated that he saw the airplane takeoff from runway 14, and it appeared to be under control. The airplane flew along the left downwind leg for runway 21 about 300-400 ft above ground level, in straight, level, and stable flight. After the airplane passed the approach end of runway 32, it pitched down, banked sharply right, and the engine throttled back. The witness said it was hard to tell if the engine was throttled back before the sudden change in pitch or in its response to the change in pitch; a loss of control/stall occurred. Another witness at AJZ stated that he heard an engine repetitively going from full engine power, then back off, and then return to full engine power. He said that when he saw the airplane, he thought the wings were rocking. The airplane banked to the right, was very low, and pitched "a lot." About 3–4 seconds later, the airplane impacted the ground. AIRCRAFT INFORMATIONThe airplane owner stated the pilot was restoring the airplane since its purchase in June 2018. The owner said that he talked to the pilot on the day before the accident, and the pilot told him that he was close to having the airplane flyable. The owner asked the pilot to call him if he was going to fly the airplane so that he could watch the flight, but the pilot did not contact him. Airplane records did not contain weight and balance information and such information was not received by the National Transportation Safety Board Investigator-in-Charge. AIRPORT INFORMATIONThe airplane owner stated the pilot was restoring the airplane since its purchase in June 2018. The owner said that he talked to the pilot on the day before the accident, and the pilot told him that he was close to having the airplane flyable. The owner asked the pilot to call him if he was going to fly the airplane so that he could watch the flight, but the pilot did not contact him. Airplane records did not contain weight and balance information and such information was not received by the National Transportation Safety Board Investigator-in-Charge. WRECKAGE AND IMPACT INFORMATIONThe accident site was about 220 feet from the approach end of runway 32 in an upright position. The wings and empennage with attached control surfaces were intact with the fuselage. The wing flaps were retracted. The airplane wings and fuselage sustained structural damage to both wings and fuselage. Postaccident examination of the airplane confirmed flight control continuity from the control surfaces to the cockpit flight controls. The horizontal stabilizer’s angle of incidence was positioned, attached, and secured to the lowest bolt hole along the leading-edge root of the vertical stabilizer. Three bags containing shot (each weighing about 24.4 lbs, 25.2 lbs, and 25.2 lbs respectively) and a fourth shot bag that was ruptured and estimated to be about the same weight as the other three, were found in the passenger seat area. One of two dumbbell weights (marked 35 lbs) was also found in the passenger seat area. Recovery personnel recovered the other dumbbell weight from an unknown location in the airplane.
The pilot’s exceedance of the airplane’s critical angle of attack during a test flight which resulted in an aerodynamic stall and impact with terrain.
Source: NTSB Aviation Accident Database
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