What was found
DURING CRUISE FLIGHT, SMOKE FROM UNDER INSTRUMENT PANEL NOTED. PILOT SECURED ELECTRICAL AND MAGNETO SWITCH AND EXECUTED A FORCED LANDING. HEAT DAMAGE TO ELECTRICAL WIRES NEAR THE BATTERY BOX. EXAMINATION OF THE RIGHT MUFFLER P/N 0450400-26, REVEALED THE AFT END PLATE P/N 0450338-18, WAS NOT IN PLACE AND NOT RECOVERED. NO RECORD OF REPAIR OR REPLACEMENT OF THE RIGHT MUFFLER. THE AIRPLANE HAD BEEN INSPECTED LAST 8 MONTHS EARLIER IN ACCORDANCE WITH AN ANNUAL INSPECTION. EROSION OF THE REMAINING FLANGE OF END PLATE WAS NOTED AND PERFORATION OF THE TUBE WAS ALSO NOTED. (X)