Cessna P210N N4629K accident near Johnstown, New York

Probable cause

A failure of the landing gear system hydraulic pump assembly for reasons that could not be determined based on available evidence. Contributing was the pilot’s failure to confirm that the landing gear was down and locked before landing.

NTSB analysis

About 30 minutes after climbing to 10,000 ft above mean sea level, the pilot began hearing “an unfamiliar buzzing or humming noise” that became increasingly louder. After attempting to troubleshoot the issue, he decided to divert to an airport along his route. Soon after, he smelled “electrical fumes” and noted smoke in the cockpit. He diverted to the nearest suitable airport for a precautionary landing and the landing gear collapsed during the landing roll. The airplane skidded on the runway and tipped to the left, substantially damaging the left elevator.

The pilot stated that he and a mechanic examined the airplane after the accident and noted that the circuit breaker for the hydraulic pump had popped and a hose near the hydraulic power pack assembly, which contains the hydraulic pump, was partially melted. They then removed the hydraulic power pack. A Federal Aviation Administration inspector subsequently oversaw a postaccident examination of the airplane. The examination revealed that hydraulic pump motor assembly displayed signatures and had an odor consistent with being overheated. Due to the hydraulic power pack being previously removed by the pilot and mechanic, the hydraulic fluid level could not be determined, and no further testing was possible to isolate malfunctions of the hydraulic pump assembly.

The pilot reported that although he visually verified that the landing gear was down before the landing, he did not observe the landing gear position indicator and verify that they were locked in the down position before landing. Had he performed this action, he could have recognized this condition before the subsequent landing gear collapse, and it is possible that he could have taken the appropriate steps to manually complete the landing gear extension cycle.

Text from the NTSB. Open the NTSB docket for ERA21LA147 for the full record.