On May 8, 2000, a Cessna 170B (registration N992EZ) was involved in an aviation accident near Delta Junction, AK. Investigators recorded the probable cause as: A loss of engine power due to an undetermined reason. A factor in the accident was unsuitable terrain for a forced landing. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A private pilot experienced an engine RPM drop to idle during cruise at 600 ft AGL. Emergency procedures failed, leading to a forced landing in trees. Post-accident inspection revealed thermal damage to the muffler internal baffling.
Accident Details
A solo private pilot reported that while cruising at approximately 600 feet above ground level, the engine RPM suddenly dropped to idle. Despite attempting emergency engine procedures, full power could not be restored. The pilot selected a forced landing area that contained trees, and the airplane sustained damage to the wings, fuselage, and empennage.
Post-Accident Examination
An FAA airworthiness inspector who examined the accident scene noted that when a probe was inserted into the muffler, something inside felt loose. The muffler assembly was removed and shipped to the NTSB investigator-in-charge. On May 15, the muffler was cut open for internal inspection. Examination revealed extensive thermal destruction of the internal baffling material. The remaining piece of baffling measured approximately 4 inches by 3 inches. The NTSB investigator attempted to position this material over the exhaust port in various ways but could not create a blockage.