Accident Details
Probable Cause and Findings
A total loss of engine power due to a shift of a crankshaft main bearing, which resulted in a lack of lubrication and subsequent overheating and failure of the engine crankshaft.
Aircraft Information
Registered Owner (Current)
Analysis
On July 12, 2023, about 1620 Alaska daylight time, a Aeronca 7DC airplane, N83391 sustained substantial damage when it was involved in an accident near Ninilchik, Alaska. The pilot and passenger were not injured. The airplane was operated by the pilot as a Title 14 Code of Federal Regulations Part 91 personal flight.
Pilot reported that he and a friend were on a scenic flight from the Homer Airport (HOM), Homer, Alaska, to the Soldotna Airport (SXQ), Soldotna, Alaska. En route he noticed the engine was not making enough power for the set power setting. At full throttle the engine was only producing about 2,400 rpm. He ran through checklist memory items for loss of engine power, which included applying carburetor heat; however, there was no change in the engine power. The pilot also opened both wing tanks to increase fuel in the header tank, which also resulted in no change. He then noticed the oil pressure gauge and oil temperature gauge both indicated zero. The pilot initiated a climb to clear rising terrain when the engine started to vibrate violently and then lost all power. He initiated a forced landing on to a road and, after touching down, he veered left to avoid cars. The airplane impacted a guardrail and then nosed over. The airplane sustained substantial damage to the fuselage and wings.
A postaccident examination of the engine revealed that the crankshaft’s No. 1 main bearing had spun, smearing metal into the crankcase and blocking the oil port. Numerous fragments of bearing material were found inside the case. The owner was not able to provide maintenance records for the engine.
Data Source
Data provided by the National Transportation Safety Board (NTSB). For more information on this event, visit the NTSB Records Search website. NTSB# ANC23LA053