What was found
ON FLIGHT, CREW REPORTED PLASTIC BURNING ODOR THROUGH THE CABIN COMING FROM ABOVE 4A. AC REMOVED FROM SERVICE. FOUND LT SIDE WALL BALLAST BY ROW 2A, BURNED AND INOPERATIVE. REMOVED AND REPLACED BALLAST ABOVE ROW 2A IAW MM 33-71-03. OPERATIONAL CHECK GOOD, AC RETURNED TO SERVICE. (K)