Accident Overview
On Sunday, August 1, 2021, at about 11:33 Japan Standard Time, a privately owned Piper PA-46-350P, registration JA4077, was landing on Runway 12 at Sendai Airport. During the landing roll, the aircraft tilted forward, and the propeller tips and lower forward fuselage contacted the runway surface. The aircraft came to a stop in the middle of the runway. The two persons on board—a captain and a passenger—were not injured.
Flight History
The flight was a familiarization flight that departed Sendai Airport at 10:47. The captain was in the left pilot seat, the passenger in the right. The aircraft performed four touch-and-go landings. On the final landing, the captain extended the landing gear, confirmed all three gear were down-locked, and approached with full flaps at 80–85 kt. The wind was from 160° at 13 kt. After a normal flare and touchdown, the nose wheel touched down, and the aircraft veered left. The captain applied right rudder, but the aircraft then veered right and pitched nose-down.
Damage to the Aircraft
The aircraft was substantially damaged. The firewall was deformed; the engine mount was deformed and fractured; the nose landing gear (NLG) door and strut were damaged; and the tips of all three propeller blades were damaged. The NLG had collapsed in the retracted direction. The actuator was found in the extended and down-locked position but had impacted the firewall, causing deformation.
Examination Findings
The engine mount includes two actuator attachment feet. The right foot was fractured. Analysis of the fracture surface revealed partial corrosion and blisters on the back side of the welded area. The design and manufacturing company had previously issued Service Bulletin 1103 (latest revision 1103F) for fluorescent penetrant inspection of the actuator attachment area every 100 flight hours. The aircraft had undergone a 100-hour inspection on November 23, 2020, but the mechanics performed only visual inspection and found no anomalies; they did not perform the fluorescent penetrant inspection. The aircraft was typically parked outdoors at Sendai Airport, which is coastal.
Analysis
The Japan Transport Safety Board determined that during the landing roll, the right actuator attachment foot fractured. This caused the load to concentrate on the left foot, deforming the engine mount and allowing the NLG to collapse in the retracted direction. The fracture surface showed corrosion and blistering, indicating that cracking had initiated before the accident and progressed over repeated flights, leading to the fracture.
Probable Cause
The probable cause of the accident was the fracture of the right actuator attachment foot due to cracking resulting from corrosion fatigue, which led to the collapse of the nose landing gear during the landing roll.