What happened
Upon arriving at his original destination, the pilot cycled the landing gear six times. During this process, the green gear-down light for the right main gear failed to illuminate. To resolve the issue, the pilot utilized the emergency extension system to blow the gear down, which subsequently caused the right main gear-down light to illuminate.
Following the landing, the pilot performed an inspection of the landing gear. However, the pilot did not contact company maintenance personnel or utilize an external lock to ensure the gear remained in a down-and-locked position. The aircraft then departed for its final destination with the gear left in the down position. During the landing roll at the second destination, the right main gear collapsed.
The investigation
An examination of the landing gear assembly revealed corrosion and scoring of the metal located inside the down-lock tube. This damage was found specifically where the teeth of the down-lock mechanism slide into the engaged position.