The pilot of a single-engine Beechcraft Sundowner plane experienced engine problems about 20 minutes into a flight from Kauai to Kalaeloa Airport in Kapolei and tried unsuccessfully to restore power, according to a preliminary report issued last week by the National Transportation Safety Board.

Eric Kawamoto, a Navy electrical engineer who has been flying for 10 years, reported that on May 23 during the climb to cruise level, the engine began to run rough, the NTSB report said.

“The pilot applied carburetor heat, which resolved the roughness, and he continued his climb to 5,500 feet mean sea level.

“As the flight was approaching the shores of Oahu, the engine began running rough in addition to a reduction of engine rpm to about 1,700. The pilot applied carburetor heat and adjusted the mixture, however, was unsuccessful at restoring engine power.

“The pilot initiated a forced landing into the ocean waters just off shore of the island of Oahu.”

The NTSB said the single-engine aircraft came to rest in about 20 feet of water, about 50 to 75 feet from the shoreline at Makaha.

Initial examination of the wreckage revealed that the forward portion of the fuselage was damaged. The wreckage was recovered from the water on May 26 and was moved to a secure location for further examination.

Kawamoto, 56, and his wife, Leslie, 52, sustained minor injuries.

Kawamoto said he chose to ditch in the ocean because a beach landing might affect beachgoers. They were rescued by lifeguards.