Incident Description
During the landing rollout, the right main landing gear collapsed, and the airplane departed the runway. The pilot reported the event to company maintenance personnel, who subsequently examined the right main landing gear assembly.
Investigation Findings
Company maintenance discovered that a dynamic brake relay—a component designed to provide a momentary surge of reverse current to the right main landing gear for positive stopping—was defective. The defective relay allowed the motor to drive the landing gear gearbox beyond its prescribed limits. This over-travel induced a bend in the right main landing gear connecting rod. When the gear down selection was made, the connecting rod was placed under a compression load, which caused it to bend further and ultimately prevented the gear from extending.
Conclusion
Examination of the aircraft's right main landing gear revealed the defective dynamic brake relay as the initiating component. The failure of this relay led to a cascading mechanical issue that resulted in the landing gear collapse and subsequent runway excursion.