Incident Description
While in flight, the engine ceased to produce power. The pilot detected smoke emanating from the defrost vent. These circumstances necessitated an emergency landing, which was carried out on a local highway.
Inspection Findings
Upon examination after the landing, it was discovered that the exhaust pipe had separated from the muffler. The hot exhaust gases were then able to melt a rocker box oil drain line. The oil leaked out, ignited, and burned the magneto 'P' lead wires. This burning caused the total failure of the engine.
Regulatory Action
Piper Airworthiness Directive 70-16-05 addresses this specific problem in earlier models of the aircraft. The Federal Aviation Administration is currently taking action to have later models included in the directive.