Primary finding
Probable cause
An overstress fracture of the left main landing gear actuator, which resulted in the failure of the left main landing gear to fully extend and lock into place.
Investigator assessment
Analysis narrative
The pilot reported the purpose of the flight was to practice maneuvers and perform system checks on the airplane. The pilot extended the landing gear during the flight, and although the gear appeared to be extended the down-and-locked light did not illuminate. The pilot made multiple attempts to lower the gear, including performing the manual extension procedures. The pilot performed a low pass over the airport and was informed by his mechanic that the gear appeared to be extended. During the subsequent landing, the right main landing gear collapsed, resulting in substantial damage to the right horizontal stabilizer and elevator. Postaccident examination revealed that the left main landing actuator barrel had a longitudinal fracture. Metallurgical examination of the fracture surfaces revealed signatures of overstress. The overstress fracture of the actuator resulted in the failure of the landing gear to fully extend. A functional test and examination of the hydraulic power pack revealed no anomalies that would have precluded normal operation.
Source record
Factual narrative
On April 11, 2024, about 1345 Pacific daylight time, a Cessna P210N, N806RC, was substantially damaged when it was involved in an accident near Auburn, Washington. 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 an annual inspection had recently been completed on the airplane and the purpose of the flight was to practice maneuvers and perform system checks in the local practice area. Once he arrived in the practice area, he lowered the landing gear, but the landing gear position indicator lights did not illuminate. The pilot said that he could hear the hydraulic pump operating continuously and he attempted to cycle the landing gear a second time. He stated he could see all three tires using the wing-mounted mirrors, and the landing gear appeared to be lowered; however, the gear down-and-locked light did not illuminate. Following several unsuccessful attempts to cycle the landing gear, he used the emergency landing gear extension procedure. While operating the emergency hand pump, he felt marginal resistance and noted that the landing gear did not extend. After completing additional troubleshooting for extending the landing gear, he conducted a low approach over the Auburn Municipal Airport (S50), Auburn, Washington. The pilot’s mechanic, located on the airport, observed the low approach and reported the landing gear looked like it was down. During the landing roll on runway 34, the right main landing gear collapsed, and the airplane veered to the right side of the runway and struck a runway sign and a light. Postaccident examination of the airplane revealed that the right horizontal stabilizer and elevator were substantially damaged. The airplane was stabilized using floor jacks and a tail stand. The seats, interior, and fuselage inspection panels were removed. The emergency hand pump was extended and pumped. Red liquid consistent with hydraulic fluid was observed coming from the left main landing gear actuator. The left main landing gear actuator was removed, and a crack about 3 ½ inches long was observed on the actuator housing. The left landing gear actuator was sent to National Transportation Safety Board Materials Laboratory, Washington, DC, for examination. The examination of the fracture surface revealed characteristics consistent with an overstress fracture. A review of the airplane’s maintenance records could not determine the age of the landing gear actuator, or if recent maintenance had been performed on it. A subsequent functional test and examination of the hydraulic power pack revealed no anomalies that would have precluded normal operation.