Incident Overview
A cargo airplane experienced a main landing gear collapse during a landing procedure. According to the pilot's account, the airplane bounced upon initial touchdown. When the aircraft contacted the runway a second time, the main landing gear gave way and collapsed.
Pilot Report
The pilot reported that during the approach, when the landing gear was lowered, the left main gear was observed extending and the green gear-down indicator light illuminated. This suggested that the gear system appeared to function correctly prior to landing.
On-Scene Investigation
Investigators conducted an examination of the landing gear system at the accident site. The landing gear was retracted and extended multiple times without any malfunctions or anomalies detected. The downlock mechanisms for the landing gear were inspected for wear; no significant wear was noted. Additionally, the distance between tire tracks left on the runway indicated that the gear was in the trailing (down) position at the time of the landing.
Manufacturer Information
According to the manufacturer's maintenance manual, all three landing gear legs must be fully down and locked before the green gear-down indicator light will illuminate. This specification is consistent with the pilot's observation that the light was illuminated during the approach.
Conclusion
The investigation did not identify a specific mechanical failure in the landing gear extension or locking systems. The gear functioned normally during post-accident tests, and the downlocks showed no wear. The tire track evidence supports that the gear was extended during the landing. No probable cause was stated in the source.