Flight Details
The pilot reported that the aircraft was on its first flight after a major engine overhaul and was being flown for maintenance evaluation. About 45 minutes after takeoff, the pilot requested a descent from 7,500 feet mean sea level (MSL).
Engine Failure
After entering an overcast cloud layer, the engine began to sputter, vibrate, and lose power. The engine then stopped and could not be restarted, prompting the pilot to declare a 'May Day' emergency.
Landing and Recovery
The aircraft broke out of the overcast over a lake at approximately 2,200 feet MSL. The pilot made a controlled landing near boats about one mile from the shore. All occupants were rescued in less than one minute. The aircraft later sank in about 90 feet of water and was recovered from the lake.
Engine Examination
A teardown of the engine revealed that the No. 5 connecting rod had separated from the piston. The stub of the connecting rod had beaten a hole in the left side of the crankcase, which resulted in oil starvation.