Symptom: My G-200 is equipped with Yaw Master rudder/brake pedals (photo 1). When applying the left brake I felt a clunk and one side of the pedal moved forward about 1/2". Although the brake effectiveness was significantly reduced, it was sufficient for taxiing.
Cause: The brake pedal pivots about a rod. A washer and a small cotter pin keep the rod in place. Apparently there is some asymmetric loading on the rod that causes it to pull outwards, causing the washer to rub against the cotter pin (photo 2). Eventually the exposed parts of the cotter pin break off, allowing the rod to back out of the hole (photo 3). Naturally the washer falls off as well, creating a FOD hazard.
History: At the time of the failure, I had put about 300 hours on the aircraft since purchase. I don't remember ever changing the cotter pins during that time, and don't know how long the cotter pins were in use before I bought the aircraft. The right pedal, seen in photo 2, was also on the verge of failure, and its cotter pin came apart in my hand.
Recommendations: 1) Replace the brake pivot cotter pins at every annual inspection. 2) Drill out the holes to accept a larger cotter pin or perhaps even a solid quick-release pin.
Photo 1: Yaw Master brake pedal
Photo 2: Pre-failure (top view)
Photo 3: Post-failure (side view)