Incident
While descending in instrument flight rules (IFR) conditions near the destination, the engine lost power at an altitude of approximately 3800 to 4000 feet. The pilot requested vectors toward land and the nearest airport. However, when the aircraft broke out of the clouds at about 1000 feet above ground level, it was still over water. Unable to reach land, the pilot ditched the aircraft in the mouth of the Potomac River, about three-quarters of a mile from shore.
Investigation
An examination of the engine revealed holes in each side of the top portion of the crankcase between the number one and number two cylinders. A subsequent teardown of the engine disclosed that the number two connecting rod had failed. Evidence indicated a lack of lubrication. The connecting rod bearings showed signs of extreme wear and heat, and the respective crankshaft journals exhibited heat and wear. Additionally, the oil pump cavity and walls were scratched and galled.
Findings
The investigation determined that the number two connecting rod failed due to a lack of lubrication. The extreme wear and heat on the bearings and journals, along with the damage to the oil pump cavity, were consistent with lubrication failure. The engine failure occurred during descent in IFR conditions, leading to the ditching.