The flight instructor was performing an introductory flight lesson for a student with her parents on board as passengers.
Rather than fly in the normal practice area, the flight instructor and student decided to fly across a channel toward an adjacent island to avoid unfavorable weather conditions.
The student flew the majority of the flight following the shoreline until the flight instructor took the flight controls and turned the airplane inland to return to the airport.
As the flight instructor flew the airplane over mountainous terrain, the engine lost partial power, and the airplane then began to descend. The flight instructor subsequently performed a forced landing into densely forested terrain in Ualapue, Hawaii, resulting in one serious injury and three minor injuries.
The airplane was not recovered from the accident site, and it could not be examined on site due to the inhospitable and remote terrain so the reason for the partial loss of engine power could not be determined.
The NTSB determined the probable cause as a partial loss of engine power during cruise flight for reasons that could not be determined because the airplane was not recovered.
NTSB Identification: WPR15LA086
This January 2015 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.