On September 2, 1992, a Piper PA-23-160 (registration N4305Y) operated by Chavossy, Louis was involved in an aviation accident near Concord, CA. Investigators recorded the probable cause as: The following Probable Cause was modified on April18, 2007, as a result of new information provided to the NTSB. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An aircraft collided with a bridge while attempting to return to the airport after reporting an emergency during a touch-and-go landing. Investigation revealed a backwards-installed plug in the crankshaft and damage to the engine crankcase and oil transfer tube.
Accident Overview
The aircraft struck a bridge while the pilot attempted to return to the airport. The pilot had reported an emergency during a preceding touch-and-go landing. Witnesses reported that both engines sounded operational and both propellers were turning. After the accident, the left engine propeller was found in a feathered position.
Investigation Findings
Investigation of the engine system revealed a plug with an outer diameter of 1.75 inches installed within the crankshaft. This plug was designed to separate oil pressure from the propeller governor. The plug was discovered to be installed backwards. Additionally, the engine crankcase was displaced aft, causing damage to the number one rod connecting journal oil transfer tube.