What happened
The pilot reported an inability to extend the aircraft's landing gear through either the standard hydraulic system or the emergency extension mechanism. After making repeated attempts to deploy the gear without success, the decision was made to perform a landing with the gear in a free-fall configuration. During the final approach, both engines were shut down and feathered. Upon touchdown, the wheels were forced upward from their free-fall position back into the wheel wells, resulting in substantial damage to the aircraft.
The investigation
A subsequent examination of the landing gear mechanism revealed significant maintenance issues. The inspection found an excessive accumulation of grease, dirt, and grit within the landing gear slide tubes, slides, and actuating chains. Additionally, rust was discovered on the surface of the slide tubes, indicating corrosion that likely contributed to the mechanical failure.
Findings
The primary factors leading to this incident were the contamination of the landing gear components and the resulting mechanical failure of the extension system. The presence of excessive debris and rust prevented the gear from locking into place during the emergency free-fall attempt, causing the wheels to rebound into the wheel wells upon impact.