Accident Details
On May 19, 2020, at about 1930 central daylight time, a Cessna 501, registration N501KM, sustained substantial damage during a landing accident at Houston Hobby Airport (HOU), Houston, Texas. The pilot, who was the sole occupant, was not injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
Landing Gear Issue
While on final approach to HOU, the pilot lowered the landing gear and observed that two of three green landing gear position indicator lights illuminated. The left main landing gear light was not illuminated, and a warning horn sounded. The pilot recycled the landing gear with the same result. The pilot informed HOU tower of the situation and asked if they could visually confirm the gear position. The tower reported that all gear appeared down, a confirmation echoed by the pilot of a commercial airliner taxiing on the airport.
Following the pilot operating handbook, the pilot performed an aggressive bank right, immediately followed by a left bank to generate lateral G-forces on the landing gear in an attempt to achieve a locked indication on the left main gear. The attempt was unsuccessful.
Upon landing, the left main landing gear collapsed. The airplane veered left and came to a stop in a grassy area adjacent to the runway, resulting in structural damage to the left wing and underbelly. The pilot exited the airplane, and airport emergency services responded. Recovery personnel manually lifted and locked the left main landing gear down, and the airplane was towed to a hangar.
The pilot reported that he decided to land because the left main landing gear indicator light had malfunctioned in years past, and it was found that the light, rather than the gear, had been the issue.
Post-Accident Examination
The landing gear was examined under the supervision of a Federal Aviation Administration (FAA) airworthiness inspector. Using ground hydraulic and electrical power, the gear was cycled about 30 times with various hydraulic pressures. The nose and right main landing gear functioned normally. The cockpit landing gear position lights (nose, left main, and right main) functioned normally. However, the left main landing gear actuator never locked in the down position under any hydraulic pressure setting. The only way to attain a locked down left main gear was to manually push the gear outward to the down and locked position. When pushed into the locked position, the left main landing gear down indicator light illuminated green.
Evaluation of the left main landing gear actuator revealed that its internal down-lock mechanism was not functioning. According to the certified repair facility, the actuator is a component normally replaced at interval (37,000 cycles) or as needed. The FAA inspector reported that the aircraft logbook showed the left main actuator was original to the airplane and was last inspected on July 6, 2017, at 5,287 cycles. The logbook did not show any recent entries concerning anomalies with the left main landing gear.