Accident Overview
On June 18, 2020, about 1345 Pacific daylight time, a Cessna 310B airplane, registration N6602B, was substantially damaged in an accident at Coeur d'Alene Airport (COE), Coeur d'Alene, Idaho. The pilot, the sole occupant, was not injured. The flight was conducted as a personal flight under Title 14 Code of Federal Regulations Part 91.
Pilot Report
According to the pilot, the aircraft was on short final with the landing gear extended when the landing gear indication light in the cockpit began to flicker. After a few seconds, the light became solid. The pilot visually confirmed that all three landing gear were extended and proceeded with the landing. Upon touchdown, the left main landing gear (MLG) collapsed, causing the airplane to slide off the runway and come to rest in an adjacent field.
Postaccident Examination
A postaccident examination of the landing gear system revealed several discrepancies. The left MLG torque link was missing cotter pins on its castellated nuts. The right MLG torque link center bolt was missing its nut and had backed out approximately two-thirds of the way from its attachment point. Downlock tension measurements were 11.3 pounds on the left MLG and 8.3 pounds on the right MLG; the Cessna 310 Service Manual specified a routine maintenance tension of 40–60 pounds. The landing gear actuator appeared mis-rigged; the emergency crank was backed off three turns after actuation of the DOWN limit switch, whereas the service manual stated it should be backed off two turns. Additionally, the nose landing gear centering mechanism was broken and rusty, and the left MLG drive tube was fractured at the actuator attachment lug.
The left MLG drive tube was sent to the NTSB Materials Laboratory for further examination. The observed features were consistent with fracture due to bending overstress at the end of the inboard clevis shaft. No pre-existing fracture features or cracking were found.
Maintenance Records
Examination of the airplane's maintenance records showed that the most recent maintenance on the landing gear system was performed on June 3, 2020. This maintenance included an MLG wheel inspection, as well as tire and brake inspections.