MIA07LA050

The airplane experienced an electrical short and total loss of engine power during cruise flight. Examination of the wreckage revealed that the airplane's left engine exhaust muffler fractured resulting in an exhaust leak. The nacelle electrical wiring run was proximate to the leak, resulting in a nose landing gear indication discrepancy and the magneto "P" leads to ground out. The total loss of engine power forced an off airport landing into trees. The inspection procedures in the Airworthiness Directive for the exhaust system were inadequate to detect the crack in the aft section of the muffler.

On February 17, 2007, about 1350 central standard time, a Bellanca 17-30A, N6641V, registered to and operated by a private individual, impacted trees during a forced landing in Fountain, Florida. Visual meteorological conditions prevailed at the time and a visual flight rules (VFR) flight plan was filed for the 14 Code of Federal Regulations (CFR) Part 91 personal flight from Tallahassee, Florida, to Fairhope, Alabama. The certificated private pilot and the passenger were seriously injured, and the airplane was destroyed from a postcrash fire. The flight originated from the Tallahassee Commercial Airport, earlier that day, about 1245.

The pilot stated that during cruise flight, at 4,500 feet mean sea level, he noticed the nose landing gear position light illuminate. He advised the air traffic controller at the Tyndall Approach Control, which was giving him VFR advisories at the time. The controller arranged for another airplane in the area to rendezvous with the accident airplane for a visual inspection of the nose gear. As the pilot was waiting for the second airplane to arrive, he lowered the gear and observed three green lights. Upon retracting the gear, all three lights extinguished. The nose gear light immediately illuminated again and the pilot saw smoke coming from the vicinity of the electrical master switch. The switch was turned off and the smoke dissipated. A few seconds later, the engine lost power, but the propeller was still windmilling. The pilot switched fuel tanks but did not elect a restart due to the suspected short in the electrical system. The pilot observed an open field and attempted to land in the open area; however, he was not able to reach the area and landed in trees. A postcrash fire ensued; he and the passenger were able to get out of the airplane before the fire destroyed it.

The postrecovery wreckage examination conducted by the National Transportation Safety Board revealed the aft one-third of the left muffler was crushed. The ball joint was separated from the muffler at the weld and remained attached to the tailpipe/ resonator. The clamp remained in place on the left ball joint with its associated hardware. The ball joint was not damaged. The amphenol connector/cannon plug located on the left side of the firewall, which houses the electrical wiring for the nose landing gear indication and the "P" leads for the engine's magnetos, was fire damaged. The routing of those wires was in the proximity of the separated muffler ball joint. The left muffler and the ball joint assembly were sent to the Safety Board Office of Research and Engineering Materials Laboratory Division. The examination revealed, among additional findings, a fracture from the 1:30 o'clock to 5:30 o'clock position on the circumferential weld of the muffler aft tube, which was completely covered with oxidation and edges of the fracture were rounded consistent with the presence of a preexisting crack or through-the-wall corrosion.

The last annual inspection to the accident airplane was September 20, 2006, at a total airframe time of 2,639.7 hours, which was about 11 hours before the accident flight. Airworthiness Directive (AD) 76-23-03R1, dated November 7, 1986, which calls for an inspection of the muffler and tailpipe areas, was complied. The mentioned AD states "To prevent exhaust system failures which could result in cabin air contamination and heat damage to components in the nacelle. Visually inspect the muffler and tailpipe assemblies for cracks paying particular attention to the ball joint welds and the outlets of the muffler and resonator."