As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) ON TAKEOFF THE AIRCRAFT EXPERIENCED A MAJOR YAW TO THE LEFT. THE YAW WAS OF A SURGING NATURE AND THE LEFT HAND ENGINE WAS SHUTDOWN. THE AIRCRAFT RETURNED TO ITS DEPARTURE POINT. POST FLIGHT INSPECTION FOUND THE PRESSURE REGULATOR HAD EXCESSIVE SCORING ON THE SEAT FACE.THE SEAT WAS REPLACED AND THEAIRCRAFT WAS GROUND RUN SERVICEABLE AND THE AIRCRAFT RETURNED TO SERVICE.