ATL04LA148 · Cessna 401B

During landing roll, a vibration was felt that simulated a "wheel shimmy condition". According to the pilot, as the airplane crossed the intersection of runway 14 and runway 23, the airplane became "light". As the pilot attempted to maintain control of the airplane, the right wing collided with the runway and the airplane slid to the right and came to a stop in the grass on the south side of the intersection of runway 14 and taxiway "A", about 2,650 feet from the approach end of runway 14. The pilot did not report any mechanical malfunctions with the airplane prior to the accident. Examination of the airplane revealed damaged to the propeller, a broken drag brace, the left flap bent upwards, damage to the underbelly of the fuselage, the right main gear collapsed and the right elevator tip scraped. Also, the right wing inboard was bent, right aileron was damaged and right flap and right wing rear spar was damaged. Further examination of the right landing gear assembly revealed that the down lock adjustment stud was broken. According to a mechanic, the visual examination of the stud fracture face disclosed that approximately 3/4 of the fracture face appeared to be old, and 1/4 of the fracture face appeared to be a fresh fracture. The maintenance history of the down lock adjustment stud was not determined nor were subsequent efforts to secure the fractured stud for further examinations successful.

Verbatim NTSB analysis and probable cause from the NTSB dataset