As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE FLT LVL390, SMOKE AND EXTREME ELECTRICAL BURNING SMELL SEEMED TO BE COMING FROM BEHIND FLIGHT ENGINEERS PANEL. SMOKE SOON STOPPED. NO EVIDENCE COULD BE FOUND. UPON INSPECTION, FOUND A-14 CARD BURNED. REPLACED CARD AS PER 33-11-03. ALL OPERATIONAL CHECKED NORMAL. A/C RETURN TO SERVICE. (M)