Engine Failure Prompts Water Landing After Takeoff (N2594X)

Event Description

Shortly after takeoff, at an estimated altitude of 200 feet, the airplane's engine lost partial power. The pilot checked the throttle for full power and initiated a turn back to the departure airport under partial power. When the airplane reached a point approximately 90 degrees to the departure runway, the pilot reported that the engine power was lost completely and the airplane lost significant altitude. To avoid endangering homes on the shore, the pilot elected to perform a water landing. The airplane subsequently impacted in about 7 feet of water.

Engine Examination

A subsequent teardown of the engine revealed a hole in the upper case halves between cylinders 3 and 4. The connecting rods for cylinders 3 and 4 were broken from the wrist pin to the crankshaft. Laboratory examination of the fracture surfaces indicated that the threaded half of one connecting rod bolt exhibited a very flat fracture surface containing arrest marks and a thumbnail pattern characteristic of fatigue propagation. The fatigue region was found to occupy approximately 80 percent of the cross-sectional area.