Load and Takeoff
The pilot loaded the airplane with two passengers and gear. The gear filled the interior to the extent that multiple attempts were required to close the door, as it was described as having filled the airplane to the roof. The rear passenger was forced to lie on top of meat and camp supplies, with two dogs in his lap. The airplane was estimated to be 772 pounds over its maximum gross weight at takeoff.
In-Flight Events
After takeoff, the airplane climbed slowly for approximately 55 minutes while the pilot maintained takeoff power. A sound resembling a sledgehammer was heard, soon after which oil began to flow into the cabin area. No reduction in engine power was observed. The oil pressure then started to decrease rapidly.
Landing
In response to the dropping oil pressure, the pilot made a precautionary landing on a beach. After landing, the airplane nosed over on grass.
Engine Examination
A teardown examination of the engine revealed that the No. 6 cylinder had failed through the head-to-barrel threaded joint. Metallurgical examination determined that the failure resulted from fatigue cracking in the cylinder head casting. According to the investigation, this type of failure occurs when the cylinder is operated at temperatures above the maximum allowable for a considerable period of time.