Nanchang CJ 6 N621JM accident near Grass Valley, California

Probable cause

A loss of brake control due to fatigue fracture of the brake control cable, which resulted in the separation of the cable from the brake handle.

NTSB analysis

During the landing roll, the pilot applied left rudder and lightly depressed the brake handle to exit the runway. About 30° into the left turn, the brakes failed, and the airplane exited the asphalt taxiway surface. Due to obstructions ahead and the downsloping terrain, the pilot applied right rudder and engine power to realign the airplane with the runway. Shortly thereafter, the airplane overran the departure end of the runway and traveled downslope while airborne. The airplane then touched down and impacted a dirt berm before it collided with a fence, nosed over, and came to rest inverted, sustaining substantial damage to the fuselage and both wings. Examination of the airplane revealed that the brake control cable was fractured near the cable thimble and was separated from the brake control handle. The fracture surfaces of the separated cable were consistent with a fatigue fracture. Six of the seven strands of wires exhibited relatively flat fracture surfaces normally oriented to the wire axis, consistent with a progressive fracture mechanism, such as a fatigue fracture. Only one strand and a few of the remaining individual wires showed evidence of minor elongation at the fracture location. It is likely that the cable completely failed during the landing roll when the pilot depressed the brake handle.

Text from the NTSB. Open the NTSB docket for WPR19LA117 for the full record.