N858AU

On October 27, 2022, about 1509 central daylight time, a Textron Aviation Inc. 172S, N858AU, was substantially damaged when it was involved in an accident near Tuskegee, Alabama. The flight instructor sustained minor injuries, and the pilot undergoing instruction was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight.

The flight instructor reported that he was assessing the abilities of the pilot undergoing instruction. They were practicing short-field landings, and the first landing was uneventful. During the second landing attempt, when the airplane was about 10 to 40 ft above ground level, the airplane’s airspeed decreased, and the sink rate increased. The flight instructor applied full throttle for a go-around, but the engine did not respond. The flight instructor further described that, “Immediately after the rapid application of the throttle to full whilst maintaining all necessary flight control inputs, our sink rate greatly increased, rather than being arrested whatsoever by the addition of full power. We sank as though the power setting had not only remained entirely unchanged but had decreased greatly. I did not have time to reference the engine instruments or the tachometer due to our rapid sink rate and distance from the runway surface, as I pitched to avoid an unrecoverable loss in airspeed.”

The airplane subsequently landed hard on the runway and veered left before departing the runway surface. The flight instructor described that after touching down he, “…did not have an opportunity to reach for and pull the throttle to idle from its setting of

full power, as my hand had been dislodged from the throttle upon impact. The engine was not producing any sound to indicate it was even running, nonetheless running at the appropriate rate given that the throttle was still set to maximum, with no change made to the aircraft by either occupants. The propeller had almost entirely stopped spinning prior to entering the grass, only striking the grass four times with no prior propeller strike at any point.” The hard landing resulted in a collapse of the left main landing gear and the nose landing gear. Examination of the wreckage also revealed substantial damage to the engine mount and lower fuselage.

The flight instructor stated that, after the accident, another flight instructor informed him that the same engine issue happened to her during a go-around the day before and that she reported the issue to the head of the operator’s maintenance department. According to the Federal Aviation Administration principal operations inspector (POI) assigned to the operator, this engine power issue was a fouled spark plug, which the operator corrected before the accident flight.

The POI stated the pilot undergoing instruction performed the first short-field landing, and the flight instructor was demonstrating and performing the second landing. Following the accident, POI downloaded data from the airplane’s primary flight display for the accident landing. According to the data, during the final 500 feet of descent toward the landing, the airplane’s indicated airspeed decreased from about 60 knots to about 50 knots as the airplane reached about 50 feet above the ground. During this time the engine rpms varied between about 1,600 to 1,000. In the final 5 seconds before the airplane touched down, the airspeed decreased below 50 knots reaching a low of 25 knots, while the engine rpm remained around 900. As the airplane touched down, the engine rpms rapidly increased to 1,700 rpm, reaching a maximum of nearly 1,900 rpm 2 seconds later, before decreasing again over the next 7 seconds to 0 rpm, while the airplane remained on the ground.