Kingsland, TX, USA
N25TX
Rans S7
The pilot and passenger had recently completed maintenance work on the engine to address engine sputtering that occurred during steep climbs. A witness who was familiar with the troubleshooting stated that, on the day of the accident, the pilot's plan was to complete steep climbs to determine why the engine sputtered during that maneuver. The wind was from the south at 15 knots and gusting to 25 knots; the airplane departed to the south into the wind. The witness reported observing what he considered a "normal" takeoff, followed by a steep 15 to 20 second climb. At the top of the climb, the nose and left wing suddenly dropped, and the airplane entered a left-turning spiral, completing 3 to 4 slow rotations before impacting the ground. The witness stated that the engine sounded normal the whole time and he did not notice anything wrong. The airplane impacted the ground in a nose- and left-wing-low attitude and came to rest upright. A postimpact fire consumed a majority of the airplane. A postaccident examination of the airplane did not reveal any anomalies that would have precluded normal operation; however, the examination was limited due to the extent of the fire damage. The accident circumstances are consistent with pilot executing a steep climb to troubleshoot an engine issue. During the steep climb in gusting wind conditions, the airplane's critical angle of attack was exceeded which resulted in an aerodynamic stall, and spin into terrain.
HISTORY OF FLIGHTOn April 21, 2019, at 1443 central daylight time, a Rans S-7S airplane, N25TX, was destroyed when it was involved in an accident near Kingsland, Texas. The pilot and passenger were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. A witness reported that the pilot had just completed a few touch-and-go landings at Shirley Williams Airport before the passenger boarded the airplane. He saw the airplane taxi back to the runway, then heard it impact the ground shortly thereafter. Another witness reported observing what he considered a "normal" takeoff, followed by a steep 15 to 20 second climb. At the top of the climb, the nose and left wing suddenly dropped, and the airplane entered a left-turning spiral, completing 3 to 4 slow rotations before impact with the ground. He stated that the engine sounded normal the whole time and he did not notice anything wrong. AIRCRAFT INFORMATIONAccording to the second witness who observed the accident, in March 2019, the pilot and passenger (who was also a mechanic) had completed maintenance work on the carburetors and synchronized them so that the engine ran smooth. The week before the accident, the pilot and passenger had dinner with the witness and told him that they were troubleshooting an issue where the engine would sputter during steep climbs. They told the witness that they cleaned the gascolator, checked the fuel lines, and verified that the propeller was adjusted correctly. The witness stated that, 1 day before the accident, the pilot flew the airplane with another passenger, but they just flew to get lunch and did not attempt any steep climbs. The pilot reported to him that the engine operated with no issues. The witness further stated that, on the day of the accident, the pilot's plan was to perform steep climbs and try to figure out why the engine was sputtering. The witness did not know if the accident flight was the first troubleshooting flight. AIRPORT INFORMATIONAccording to the second witness who observed the accident, in March 2019, the pilot and passenger (who was also a mechanic) had completed maintenance work on the carburetors and synchronized them so that the engine ran smooth. The week before the accident, the pilot and passenger had dinner with the witness and told him that they were troubleshooting an issue where the engine would sputter during steep climbs. They told the witness that they cleaned the gascolator, checked the fuel lines, and verified that the propeller was adjusted correctly. The witness stated that, 1 day before the accident, the pilot flew the airplane with another passenger, but they just flew to get lunch and did not attempt any steep climbs. The pilot reported to him that the engine operated with no issues. The witness further stated that, on the day of the accident, the pilot's plan was to perform steep climbs and try to figure out why the engine was sputtering. The witness did not know if the accident flight was the first troubleshooting flight. WRECKAGE AND IMPACT INFORMATIONThe airplane departed on runway 16 and impacted the ground near the south end of the runway, as seen in figure 1. Figure 1 – Aerial image of the accident site The accident site consisted of a small initial impact point in the ground about 20 ft south of the main wreckage. The impact point was defined by a divot in the ground which contained a broken red lens, the pitot tube, and a piece of left wing tip. Another impact area was about 6 ft south of the main wreckage, which was about 3 ft in diameter and about 4 inches deep. The small crater contained white paint chips, plexiglass, a propeller blade, and the engine oil filter. Another small divot was observed under the outboard leading edge of the right wing. The three impact areas were in a relatively straight line in a north-south orientation. The airplane came to rest upright facing southwest and was mostly consumed by postcrash fire. An examination of the airframe did not reveal any anomalies that would have precluded normal operation. The engine remained attached to the engine mounts, which were broken from the airframe. The engine was mostly intact and severely damaged by fire. The propeller hub remained attached to the crankshaft and one blade remained attached to the hub. The second blade was broken from the hub at the blade root and was found next to the initial engine impact crater – it exhibited chordwise scratches on the face. The third blade was also broken from the hub at the blade root and was found about 20 ft west of the main wreckage – it exhibited chordwise scratches and the blade tip was separated. The engine was examined at a secure facility and exhibited significant thermal damage from the postimpact fire. The fuel pump was partially consumed by the fire and a full examination was not possible. According to the engine manufacturers guidance and the fuel pump serial number, the fuel pump had a five-year time limit and should have been replaced in 2010. The engine did not reveal any anomalies that would have preclude normal operation; however, the examination was limited due to the thermal damage. MEDICAL AND PATHOLOGICAL INFORMATIONAn autopsy of the pilot was performed by Travis County Medical Examiner, Austin, Texas. The cause of death was blunt force injuries. Toxicology testing of specimens from the pilot, performed by the FAA Forensic Sciences Laboratory, identified three previously reported medications: amlodipine, hydrochlorothiazide, and rosuvastatin. Also present were two other medications: naproxen and salicylate. These medications would not have posed a hazard to the safety of flight. An autopsy of the pilot-rated passenger was performed by Travis County Medical Examiner, Austin, Texas. The cause of death was blunt force injuries. Toxicology testing of specimens from the pilot-rated-passenger did not identify any drugs or tested-for substances.
The exceedance of the airplane's critical angle of attack during a steep climb after takeoff, which resulted in an aerodynamic stall and spin into terrain.
Source: NTSB Aviation Accident Database
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