Event Description
While maneuvering, the pilot moved the landing gear handle to the down position and received an unsafe indication for the nose landing gear. He attempted to troubleshoot the system and lower the landing gear manually, but was unsuccessful. A normal landing was performed to the runway, and the airplane began to roll out on all three landing gear. While decelerating through approximately 40 knots, the nose gear collapsed, the propeller struck the runway, and the airplane slid to a stop on its nose.
Examination Findings
Examination of the nose landing gear revealed that a downlock actuator pin on the nose landing gear actuator had failed due to fatigue. The pin had worked partially out of its clevis half. The broken pin contacted the actuator arm piston and prevented the full travel of the nose landing gear to the down and locked position.
Maintenance History
A manufacturer's service bulletin that addressed the inspection and replacement of the downlock pins had not been completed.