What was found
TO+15 MIN SMOKE & FUMES IN COCKPIT, UNKNOWN SOURCE. COCKPIT DOOR POWER & RECIRC FANS TURNED OFF. SMOKE DISSIPATED SOME. RETURN TO ORIGIN. CHECKED RECIRC FANS, ALL CHECKED GOOD, CHECKED MUX SYSTEM OPS CHECK GOOD. CHECKED WIRING IN OVERHEAD, FOUND NO PROBLEMS. CHECKED WIRING IN CAC ALL CHECKED GOOD. CHECK AVIONIC BAY NO SMELL OR SMOKE NOTED. NO APPARENT BURNT WIRING. RAN ALL 3 ENG OPERATED PACKS NO SMELLS NOTED. PERFORMED VISUAL WALKAROUND OF OUTSIDE OF ACFT NO DEFECTS NOTED. NO POPPED C/B'S OR WARNINGS DETECTED, ACFT OK FOR FURTHER FLIGHT.