A four-seat Big Island tour helicopter was substantially damaged last week after landing at Kona Airport, according to a preliminary study by the National Transportation Safety Board.

No one was injured in the accident that occurred at 7:45 a.m. Aug. 26 after the Robinson R44 II helicopter landed at the Kailua-Kona airport with two certified helicopter instructors on board.

According to the NTSB report released recently, the flight instructor who was “the pilot in command” reported problems after the helicopter landed and the aircraft “began to gently oscillate fore and aft.”

The pilot said the oscillations became more severe, with one main rotor blade, the tail boom and the lower vertical fin hitting the ground.

“The tail boom and lower vertical fin were substantially damaged as the result of the impact with terrain,” according to the NTSB report.

The flight had left Kona Airport at 7:15 a.m.

Federal Aviation Administration records show the helicopter, which was manufactured in 2005, is owned by Hawaii Pacific Aviation, which runs aerial tours of Oahu, Hawaii island and Kauai under the name Mauna Loa Tours and operates a flight school.