Ameriflight Swearingen SA227 AC accident

The pilot was concluding the Part 135 cargo flight when the airplane landed hard and departed off the right side of the runway. The pilot reported that the airplane was flying wings level with the nose aligned with the runway and on a normal glidepath to the runway until it crossed over the runway threshold. He stated that the airplane entered a right roll shortly after he reduced engine power for the landing flare, and that the roll became more pronounced as the landing flare continued. He was unable to regain control of the airplane before it landed hard on the right main landing gear with the airplane rolled about 20° right-wing-down. The airplane then departed off the right side of the runway where the nose landing gear collapsed. The fuselage, right engine nacelle, right-wing main spar, and forward pressure bulkhead were substantially damaged during the hard landing.

A review of automatic dependent surveillance-broadcast (ADS-B) data revealed that the pilot did not fly a stabilized approach as defined by the operator’s general operations manual. Specifically, the airplane’s descent rate exceeded the operator’s 1,000 feet per minute (fpm) limitation, the airplane’s airspeed was not maintained at the specified approach speed, and the airplane was not wings level and aligned with the runway at 300 ft above the touchdown zone elevation. At 1,000 ft above the touchdown zone elevation, the airplane was descending on the base leg at 2,055 fpm and was 5 knots below the specified approach speed. During the left turn from base leg to final approach the airplane’s descent rate reached 2,929 fpm, which was nearly 3 times the operator’s limitation for a stabilized approach. The airplane crossed over the runway threshold about 43 ft above ground level while in a 1,015 fpm descent. About 3 seconds later, the airplane touched down on the runway while descending 733 fpm and 36 ft right of the centerline with a ground track about 1.5° right of the runway course. The airplane came to rest in the grass infield between the runway and a taxiway.

Although the pilot postulated that the right roll during the landing flare was due to a right engine malfunction, his recollection of the airplane’s flight path to the runway was not consistent with the recorded ADS-B data. The pilot’s failure to fly a stabilized approach resulted in an excessive descent rate, hard landing, and loss of control. Additionally, postaccident examination revealed no evidence of a preexisting mechanical malfunction or failure that would have precluded normal operation of the airplane.

Verbatim NTSB analysis and probable cause from the NTSB dataset