20110113000359I

The pilot reported that after selecting gear down while on approach, a positive "down and locked" indication was not obtained. He cycled the gear several times with the same result. Two passes down the runway were completed, and the tower advised that the gear appeared to be down. On landing, everything initially seemed normal, but as the aircraft speed decreased and the aircraft settled, the nose gear collapsed and the aircraft came to rest on the main gear and the aircraft nose. During a follow up discussion with the pilot, he stated that when cycling the gear down, the hydraulic pump had continued to run. The mechanic who recovered the aircraft determined that the nose gear was unable to lock in the down position due to a discrepancy in the nose gear retraction actuator assembly (p/n 1280514-1). A pin (LH) (p/n 1280209-1) migrated inboard from its fixed location. On extension of the gear, the nut (p/n 9880506-1) attached to the piston (p/n 1280241-1) on the displaced pin, which stopped the gear from reaching its fully extended position.