Machinery Parts Company

Piper PA-31-310 Navajo

Following a normal landing, the pilot felt no wheel braking action on the left wheel, and the brake pedal went to the floor. The pilot attempted to maintain directional control; however, the airplane departed the right side of the runway and traveled into the grass. The landing gear collapsed, and the airplane came to a stop, sustaining structural damage to the left wing spar. Postaccident examination confirmed that the left brake was inoperative and revealed a small hydraulic fluid leak at the shaft of the parking brake valve in the pressurized section of the cabin. Air likely entered the brake line at the area of the leak while the cabin was pressurized, rendering the left brake inoperative.