As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW - FLT 1507 - EN ROUTE DFW-YVR - AFTER TAKEOFF, AIRCRAFT BEGAN A SEVERE FISHTAILING MOTION FOR ABOUT 30 SECONDS. AIRCRAFT RETURNED TO DFW AND LANDED WITHOUT INCIDENT. REPLACED ALL THREE RUDDER POWER CONTROL UNITS. SYSTEM GROUND AND FLIGHT CHECKED NORMAL OPERATION. (M)