Incident Overview
During cruise at 6,500 feet mean sea level, the airplane's engine began to run rough. Two to three minutes later, the engine stopped operating, and the pilot requested vectors to the nearest airport. While setting up for a forced landing, the cabin filled with smoke, prompting the pilot to crack open the cabin door to evacuate it. The airplane touched down short of the runway and sustained main landing gear damage.
Postcrash Examination
Postcrash examination revealed breaches in the muffler and muffler shroud. These breaches allowed engine exhaust to impinge on and burn components of the nose landing gear, the air induction system, and the lower fuselage.
Metallurgical Findings
The NTSB Materials Laboratory examined the muffler and determined that it failed due to scaling and intergranular attack. This degradation occurred over a period of time and would have been evident 30 flight hours earlier when the airplane underwent an annual inspection.