What happened
Following an emergency reported during a preceding touch-and-go landing, the pilot attempted to return to the airport. During this maneuver, the aircraft collided with a bridge. Witnesses at the scene observed that both engines appeared to be operational and both propellers were rotating; however, following the impact, the propeller on the left engine was found in a feathered position.
The investigation
Technical examination of the wreckage focused on the engine components. Investigators discovered a 1.75-inch outer diameter plug installed within the crankshaft, intended to separate oil pressure from the propeller governor. The investigation revealed that the engine crankcase had been blown aft, which resulted in damage to the number one rod connecting journal oil transfer tube. Further examination of the aforementioned plug determined that it had been installed backwards.