On February 17, 2007, a Bellanca 17-30A (registration N6641V) was involved in an aviation accident near Fountain, FL. Investigators recorded the probable cause as: A loss of engine power due to a cracked engine exhaust muffler. Contributing to the accident were the inadequate inspection procedures of the muffler system and the routing of the "P" leads wiring for the magnetos. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An aircraft experienced an electrical short and total loss of engine power during cruise after a left engine exhaust muffler fractured, causing an exhaust leak that affected wiring and led to an off-airport landing into trees.
Incident Overview
During cruise flight, the aircraft encountered a total loss of engine power due to an electrical short. The loss of power forced an off-airport landing into trees.
Examination Findings
Post-incident examination of the wreckage revealed that the left engine exhaust muffler had fractured, resulting in an exhaust leak. The nacelle electrical wiring run was located proximate to the leak site. This proximity led to a nose landing gear indication discrepancy and the grounding of the magneto "P" leads, which caused the electrical short and subsequent total loss of engine power.
Exhaust System Inspection
The inspection procedures specified in the Airworthiness Directive (AD) for the exhaust system were found to be inadequate to detect the crack in the aft section of the muffler. The crack was not identified during the prescribed inspections, allowing the condition to progress to failure.