Johnstown, NY, USA
N4629K
CESSNA P210N
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.
On March 2, 2021, about 0747 eastern standard time, a Cessna P210N, N4629K, was substantially damaged when it was involved in an accident near Johnstown, New York. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that about 30 minutes after reaching a cruise altitude of 10,000 ft above mean sea level, he started 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 informed the air traffic controller that he had “smoke in the cockpit” and wanted to divert to an even closer airport, Fulton County Airport (NY0), Johnstown, New York. He opened his window, descended toward NY0, listened to the local weather, and performed a landing checklist upon entering the left downwind leg of the traffic pattern for runway 28. During the subsequent landing roll, the landing gear collapsed. The pilot attempted to maintain control; however, the airplane skidded on the runway and tipped to the left, substantially damaging the left elevator. During a postaccident interview, the pilot reported that although he visually verified that the landing gear was down, he did not verify that the gear status light was green, indicating the gear were locked in the down position, before landing. He 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 postaccident examination of the airplane under the supervision of a Federal Aviation Administration inspector revealed that the plastic sump jar attached to the hydraulic power pack and mounted next to the motor assembly was hanging in the center pedestal by its plumbing and was disfigured consistent with the motor assembly overheating. The motor assembly also showed signs of contact with the sump jar and had an odor consistent with being overheated. The hydraulic pressure switch wires appeared normal. Removal of floor panels revealed evidence of hydraulic fluid, although not enough to suggest an external system leak. No leaks were identified in the main landing gear actuators and plumbing. The hydraulic pump motor contactor was tested and found open using an Ohm meter. 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. The Pilot’s Operating Handbook for the airplane explained that the landing gear extraction, retraction, and down lock operation was accomplished by hydraulic actuators powered by an electrically driven hydraulic power pack and that the system should be checked at 25-hour intervals to ensure that there was sufficient hydraulic fluid. There is a CAUTION note which read, “If for any reason the hydraulic pump continues to run after gear cycle completion (up or down), the 30-amp circuit breaker . . . should be pulled out. This will shut off the hydraulic pump and prevent damage to the pump and motor. During normal operation, when the gear handle is placed in the UP position the hydraulic pump runs and retracts the gear. Once the gear is in the UP position, hydraulic pressure builds until the pressure switch turns off the hydraulic pump, trapping the pressure and keeping the gear retracted. When the handle is placed in the DOWN position the pressure holding the gear up is released and the gear free fall to a hanging position. While the gear is dropping the pump builds up pressure in the extend lines until the gear are pushed into the down and locked position. If the system does not have enough pressure/fluid the gear will hang down but not make it forward to the locked position. A hand-operated hydraulic pump is provided for manual extension of the landing gear in the event of a hydraulic or electrical system failure.” The Pilot’s Operating Handbook included the following landing gear malfunction procedure: LANDING GEAR FAILS TO EXTEND 1. Landing Gear Level – DOWN 2. Emergency Hand Pump – EXTEND HANDLE and PUMP (perpendicular to handle until resistance becomes heavy – about 35 cycles) 3. Gear Down Light – ON 4. Pump Handle - STOW
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.
Source: NTSB Aviation Accident Database
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