Incident Overview
During taxi, ground witnesses noted black smoke emanating from the exhaust of an airplane. As the takeoff ground roll commenced, the engine began to lose power. The aircraft rotated off the runway approximately at the midfield point, after which the engine continued to run roughly and miss. The airplane exhibited poor climb performance, and observers noted the landing gear and lower fuselage contacting tree branches.
Post-Event Examination
A metallurgical analysis of the muffler system was conducted. The examination determined that the right cone baffle of the muffler had separated from the assembly as a result of oxidation. The fracturing mode was assessed as most probably progressive in nature, and the cone had separated at some point prior to the event. However, due to oxidation, the exact mode of fracturing could not be conclusively established.
Further inspection of the muffler revealed that the end plates and inlet tubes displayed deformation and did not meet the manufacturer's specifications. The engine and propeller were examined, but those components not consumed by the post-impact fire showed no additional anomalies.
Findings
No explicit determination of a probable cause was provided in the source material. The investigation identified the muffler cone separation due to oxidation and the non-conforming end plates and inlet tubes as factual conditions present on the aircraft.