What was found
AIRCRAFT PITCHED DOWN AND STARTED A LEFT TURN, THEN RIGHT TURN. YAW DAMP OFF AND IT STILL WANTED TO GO BACK TO LEFT. PERFORMED RUDDER PCU ADJ/TEST. NO DEFECTS NOTED. PERFORMED RUDDER PCU SECONDARY SLIDE OPS TEST, NO DEFECTS NOTED. REMOVED AND REPLACED YAW DAMPER DOUPLER, AS PRECAUTIONARY. FUNCTIONAL CHECK GOOD. COMPLIED WITH RUDDER PCU INTERNAL LEAKAGE CHECK, TEST GOOD. REMOVED AND REPLACED A CHANNEL FCC, FCS, PRECAUTIONARY. BITE TEST GOOD.