SEA02LA095 · Cessna 441

After takeoff, the pilot discovered that the right main gear had not retracted. He unsuccessfully re-cycled the gear twice, and then deactivated the landing gear system in order to prevent porting of hydraulic fluid. Prior to landing, the pilot lowered the gear and insured that all of the landing gear green (down and locked) lights were illuminated, and that the gear in-transit light was extinguished. Although the touchdown and initial part of the landing roll were uneventful, as the aircraft decelerated to about 55 knots, the right main gear slowly collapsed. A post-accident inspection of the right main gear determined that the roll pin that holds the forward gear pivot pin in its slot in the gear trunnion had fractured, allowing the pivot pin to work its way loose over time, and ultimately resulting in a misaligned gear trunnion that jammed during the retract cycle. The jamming during the attempted retraction exacerbated the misalignment, and that, along with the looseness of the pivot pin, created a situation where a low load force was able to cause the gear to collapse during the landing roll. An inspection of the pin by the NTSB metallurgical laboratory revealed that there was no evidence of fatigue along the fracture surface, and that the fracture features were consistent with overstress. The investigation revealed no evidence of unusual wear or damage in the area of the pivot pin or its phenolic bearing, nor was there a record of any recent event that would have exposed the gear pivot mechanism to an overload situation.

Verbatim NTSB analysis and probable cause from the NTSB dataset