On September 29, 1993, at 1418 hours Hawaii standard time, a Schweizer 269C helicopter, N150CA, ditched in the Pacific Ocean about 4 miles off shore from the island of Molokai, Hawaii. The ditching was precipitated by a pilot reported main rotor problem. The helicopter was operated by the pilot, and was on an inter island cross country business flight. Visual meteorological conditions prevailed for the operation, which was conducted under the provisions of 14 CFR Part 91 of the Federal Aviation Regulations. The helicopter sustained substantial damage and sank. The certificated commercial pilot, the sole occupant, was not injured. The flight originated at the Honolulu International Airport, Honolulu, Hawaii, on the day of the mishap at 1345 hours. According to the pilot's verbal and written reports, the helicopter had just completed a 1,200 hour maintenance inspection and the pilot was returning to his heliport when the accident occurred. The aircraft was in cruise flight when the pilot noticed the main rotor speed slowly decay. The pilot said he increased the throttle; however, the needle split between the engine and rotor speed continued to widen. The pilot reported that when he could no longer maintain altitude he ditched the helicopter in the ocean and was picked up by a U.S. Marine Corps helicopter.