On September 23, 1990, a Piper PA-12 (registration N2770M) operated by North Country Flying Service was involved in an aviation accident near Franconia, NH. Investigators recorded the probable cause as: The center muffler baffle broke loose and blocked the exhaust flow, resulting in a partial loss of engine power. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During a sightseeing flight at 1500 feet, the pilot heard a backfire and experienced partial power loss, necessitating an emergency landing in trees. Investigation revealed a broken center muffler baffle blocking exhaust flow.
Incident Description
A sightseeing airplane was cruising at 1,500 feet when the pilot reported hearing a backfire and subsequently experiencing a partial loss of engine power. The pilot determined that sufficient power was not available to continue flight and performed an emergency landing in trees. The aircraft came to rest in the wooded area.
Investigation Findings
Following the incident, a maintenance facility examined the engine. The investigation found that the center muffler baffle had broken loose and become dislodged. This broken baffle blocked the exhaust flow, which resulted in a partial loss of engine power. The condition of the baffle led to the power reduction experienced during the flight.
Conclusion
The partial power loss was directly attributed to the mechanical failure of the muffler baffle. No other contributing factors were identified in the examination.
Probable cause
The center muffler baffle broke loose and blocked the exhaust flow, resulting in a partial loss of engine power.