Incident Summary
During the climb-out phase of flight, both pilots heard a pop emanating from the right side of the aircraft beneath the right seat. In response, the certified flight instructor (CFI) performed a landing gear extension. The left main landing gear extended and locked normally, but the right main gear extended only partially and then retracted simultaneously as the left gear lowered and locked. Manual landing gear extension procedures were attempted, but the right main gear failed to extend. An emergency landing was subsequently attempted. During the landing rollout, the airplane veered to the right and departed the runway surface. The right wing and right horizontal stabilizer sustained damage upon ground contact.
Examination Findings
Post-incident examination of the right main landing gear actuator assembly revealed that the actuator body was cracked in two locations near the bearing cups. One of the cracks exhibited fatigue striations that originated at the corner formed by the intersection of the 2.25-inch inner-diameter surface of the gear housing and the 1.0-inch inner-diameter surface of the linear actuator portion of the housing. Further inspection of this corner identified circumferential scouring marks consistent with grinding or filing marks.
Maintenance History
According to the maintenance logbooks, the landing gear actuator was originally installed on the aircraft and had accumulated approximately 7,000 flight hours and 21,000 cycles. The airplane manufacturer specified no life or component time limit for this actuator.