CEN19FA099

The flight instructor and student pilot were conducting takeoffs and landings in the airport traffic pattern. A flight instructor and pilot on the ground reported that the accident airplane's engine was "cutting in and out" or "sputtering" following an aborted landing. Both witnesses reported that the airplane appeared to be maneuvering to return to the runway when the airplane entered a left turn, then descended in a steep, nose-down attitude consistent with an aerodynamic stall. The common traffic advisory frequency recording captured a transmission that indicated the flight instructor might attempt to return to the airport. The airplane impacted a tree and then a road sign in a mostly residential area. A postaccident examination of the airframe and engine revealed no mechanical malfunctions that would have precluded normal operation. The propeller exhibited signs of rotation and propeller strike marks were found on the ground at the accident site. Although the witness reports indicated a possible loss of power, the reason for the partial loss of engine power could not be determined based on the postaccident examination. After the partial loss of engine power, the flight instructor attempted a turn at low altitude, during which he failed to maintain proper airspeed and exceeded the airplane's critical angle of attack, which resulted in an aerodynamic stall and a loss of control at an altitude too low for recovery.

The Cessna 172 Pilot's Operating Handbook states that the aerodynamic stall speed for flaps down (40°) is 52 kts at a 0° bank angle, 54 kts at a 20° bank angle, 59 kts at a 40° bank angle, and 73 kts at a 60° bank angle. The airplane was equipped with a stall warning indicator. On March 14, 2019, about 1340 central daylight time, a Cessna 172, N8620B, sustained substantial damage when it was involved in an accident near Lakeway, Texas. The flight instructor sustained serious injuries and the student pilot sustained fatal injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. The purpose of the flight was for the student to practice crosswind takeoffs and landings. The flight instructor was unable to recall the events leading up to the accident. Another flight instructor saw the accident airplane abort two landings, which he surmised was due to the gusting wind conditions. As the airplane flew upwind after the second aborted landing, he heard the engine begin to sputter. The airplane then turned back toward the airport, flew over his location at the airport fuel pump, then turned right away from the runway before entering a left turn toward the runway from about 500 to 600 ft above ground level He stated that from his view on the ground, it appeared that the flight instructor was flying the airplane at that point. The airplane stalled and descended straight toward the ground, "wing and nose" first. A pilot, was who receiving instruction with the eyewitness flight instructor, reported that he saw the airplane turn back toward the runway after conducting a go-around. The airplane proceeded over the runway and he heard the engine "sputtering." He saw a puff of "darker exhaust" come out of the engine and heard the engine restarting. The airplane maneuvered toward a left downwind leg for the runway, then "appeared to abruptly stall and roll to its left in a nose-down attitude." A pilot who lived near the northwest end of the airport reported that the airplane got his attention as the sound from the engine was "unusual." He saw the airplane's flaps extended and stated that the engine noises were not the sound of an engine making any appreciable power. The common traffic advisory frequency recording for the airport just before the time of the accident, recorded a transmission stating, "Lakeway traffic, Skyhawk making a 180 to land Lakeway." The Travis County Medical Examiner's Office, Austin, Texas, conducted an autopsy of the student pilot. His cause of the death was multiple blunt force injures. Toxicology testing for the student pilot was performed at the FAA Forensic Sciences Laboratory and was negative for carbon monoxide, ethanol, and tested-for drugs. The wreckage was located about 930 ft southwest of the runway 34 threshold at an elevation of about 915 ft mean sea level (msl) in a mostly residential area. The airplane initially impacted a tree and road sign on a heading of about 59°, andvarious propeller strike marks on the asphalt were observed in the direction of travel. The airplane traveled about 180 ft to the northeast across a road before it came to rest on a heading of about 182°. The airplane sustained substantial damage to the fuselage, both wings, and the empennage. The airframe was found in a tail-high attitude off a road in an area of grass. The front of the airplane, including the engine and propeller, came to rest in a tree line. Witness marks on the airframe indicated that the wing flaps were fully extended (40°) at the time of impact. All structural components of the airplane were located at the accident site. Flight control continuity was established throughout the airframe. Engine control cable continuity was confirmed. The carburetor was found separated in two pieces. The two-blade metal propeller was found attached to the crankshaft. The propeller spinner exhibited evidence of rotation. Both blades were bent aft and one blade was severely twisted. The engine was transported to the manufacturer's facility for a teardown and examination under the supervision of the NTSB investigator-in-charge. During the examination, no preimpact mechanical malfunctions or failures with the engine were noted. Review of the airplane's maintenance records revealed no evidence of uncorrected mechanical discrepancies with the airframe and engine.