Federal investigators have found no reason for the loss of engine power that prompted a pilot to make a forced landing in brush land in Central Maui in June.

And they might never determine the cause.

A helicopter recovering the wreckage dropped it into the ocean, and it took another two days to retrieve parts of it after the saltwater dunk — which resulted in severe corrosion.

The June 16 flight included three passengers and a commercial pilot who reported a loss of engine power in the Waihee-Waiehu area en route from Honolulu to Kahului.

No one was injured, but the single-engine aircraft, a Piper Pa-28-181 owned by Mokulele Iki LLC of Kihei, sustained damage to the left wing and fuselage during landing, after striking bushes and trees, according to the report, filed with the National Transportation Safety Board on Dec. 12.

The pilot told a federal investigator that he was cruising at about 1,500 feet above sea level when he noted a slight hesitation in the engine.

The pilot said he switched fuel tanks, but after five to 10 minutes he noticed a second hesitation in the engine and began troubleshooting.

He said engine power began to fluctuate and the plane couldn’t maintain altitude, so he was forced to make a landing in an open field.

As the airplane was being towed by a helicopter to Kahului Airport for examination, it was dropped into the ocean, and parts of it were recovered two days later, the report said.

Some parts of the airplane recovered from the ocean were wet and contained sand, according to the report.

"The reason for the loss of engine power was not determined," the report said.

The engine and one wing were recovered from the ocean, including the carburetor and the left and right magnetos, which showed severe corrosion.

"Examination of the recovered engine revealed signatures consistent with saltwater submersion," the report said.

There was no evidence of "catastrophic mechanical malfunction" to the crankcase, according to the report.

Pacific Helicopters, the firm that towed the aircraft, said the damaged airplane had a bent wing after striking a tree and became unstable as it was lifted in the air, forcing the pilot to detach it.

"One side lifted faster than the other," said Martin Adams, Pacific Helicopters’ director of operations. "It was not a stable load."

Mokulele Iki was unavailable for comment.