Cessna 421 N5929M accident near Charleston, South Carolina

Probable cause

Inadequate maintenance, which resulted in the collapse of the right main landing gear during landing.

NTSB analysis

The commercial pilot was concluding a personal flight with two passengers on board. The pilot reported that, during the landing roll and after a normal touchdown on the concrete runway, the right main landing gear (MLG) collapsed. The airplane then veered right and struck two runway lights, which resulted in substantial damage to the right wing rear spar.

Examination of the airplane revealed that the right MLG down-lock bellcrank was fractured and had separated from its respective trunnion. The bellcrank bolt was sheared at the bolt head, consistent with overload. The upper end of the bellcrank remained attached to the outboard push-pull tube. The lower end of the bellcrank, which attached to the rod end fitting at the lower side link, was broken, consistent with a ductile tension failure. The fracture location was consistent with additional stress that would have been placed on the bellcrank if the landing gear was not properly rigged; however, damage to the landing gear precluded the ability to functionally check or verify whether the gear was properly rigged. Review of maintenance records revealed that the airplane had been operated for about 4 hours since its most recent annual inspection, which was performed about 2 months before the accident. At that time, maintenance, including the adjustment of the right MLG travel, was performed on the airplane.

Text from the NTSB. Open the NTSB docket for ERA14LA170 for the full record.