As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX- AFTER PUSH BACK AND AFTER PITOT HEAT ON, WE NOTICED LIGHT SMOKE BELOW AND OUTSIDE OF FLIGHT DECK WINDOWS. RETURNED TO THE GATE. APPLIED AC EXTERNAL POWER TO ACFT, INSPECTED PITOT TUBES FOR SIGNS OF DAMAGE, NONE NOTED. OPERATED PITOT HEAT FOR APPROX. 5 MINUTES, NO ABNORMALITIES NOTED. RETURNED TO SERVICE. NO PARTS REPLACED.