MIA00LA018

After 30 minutes in flight the pilot reported that smoke started entering from right side defrost duct. He elected to land at the nearest airport,14 nautical miles north of his location. About 3 miles from the airport fire started inside the cockpit near the right side rudder pedals. He decreased power and started descending towards a field. The last thing he remembered was crossing power lines. A detailed inspection of the muffler revealed, the muffler had two areas of burn-through damage. The aircraft fire wall had an area about 14 inches in diameter with indications of severe overheating. It was concluded that a faulty exhaust muffler caused the aircraft's firewall to overheat and smolder the aircraft's firewall insulation. The maintence records did not indicate that the exhaust muffler had ever been replaced.

On October 29, 1999, about 1050 eastern daylight time, a Piper PA-22-150, N2648P, registered to a private individual, impacted with the ground during a forced landing near Newberry, South Carolina. Visual meteorological conditions prevailed at the time, and no flight plan was filed for the 14 CFR Part 91 personal flight. The airplane sustained substantial damage. The private-rated pilot reported serious injuries. The flight had departed from Thomson, Georgia, en route to Salisbury, North Carolina, at 1000.

According to the pilot, "...after 30 minutes in flight smoke started entering from right side defrost duct...my GPS gave [nearest airport]...14 nautical miles at 360 degrees heading...opened my window vents because my eyes were starting to water. Approximately 3 miles from airport fire started inside near right side rudder pedals...I decreased all power at about 3,000 feet msl [and] started descending towards field that I saw. I next remember crossing power lines and that was the last thing I can remember...."

A detailed inspection of the muffler was conducted by the FAA. The FAA inspector stated that the inspection revealed, "...the muffler had two areas of burn-through damage. The aircraft fire wall had an area about 14 inches in diameter with indications of severe overheating." In addition, the inspector wrote that it was his opinion, "...that a faulty exhaust muffler caused the aircraft's firewall to overheat and smolder the aircraft firewall insulation. The maintence records do not indicate that the exhaust muffler had ever been replaced."

The total time on the airframe was 1845 hours. The last inspection on the muffler was April 8, 1999, when AD 68-05-01, was complied with. AD 68-05-01, "...Inspect...the engine exhaust muffler and shroud assembly (including the internal baffle tube and tail pipe), carburetor heat shroud and air duct, support braces, clamps and brackets, exhaust stacks and manifolds...(f) remove muffler assembly...and visually inspect exterior and interior surfaces with a probe light and mirror for signs of cracks, corrosion, burn-throughs, heat damage, collapsed stack, or weld separations...."