Faulty rotor mast caused Pohang chopper crash

A months-long investigation concluded on Friday that a Marine Corps helicopter crash in July that killed five soldiers was caused by a fracture in the helicopter’s rotor mast.

A team of civilian, government and military experts determined that the fracture was first caused during the production process. The subcontractor that produced the rotor mast mistakenly used a water cooling-type heat treatment program when it was supposed to use an air cooling-type program.

Even though there was a clear manufacturing error, the problematic rotor mast was shipped anyway. The fracture widened once pressure was put on during the helicopter testing process, eventually leading the main rotor to become separated from the rotor mast. The Korea Aerospace Industries developed the Marineon with technological support from Airbus Helicopters, whose supplier produced the rotor mast. Airbus has yet to announce an official statement about the investigation results. The investigators, in addition, ultimately ruled out any possibility of foul play or mistakes that could have been made by the pilots.

“Upon analyzing the flight data, we have come to the conclusion that [the pilots] followed all flying protocols and the helicopter was operating with no problem before the rotor mast separated from the helicopter,” according to the report from the investigation team. “We will accept the investigation results and pledge to prevent any other accident recurring because of a similar quality control reason,” said KAI after learning the results. “In the future, we will invest our utmost care into making sure that our aircraft can be trusted by military personnel and the public.”

The Marine Corps has also added that they will educate future helicopter pilots to make such an accident does not happen again. Five service members were killed when the MUH-1 Marineon, the Marine variant of the military’s KUH-1 Surion helicopter, crashed at a military airport in Pohang, North Gyeongsang, on July 17.

The Marines first received the helicopters in July and plan to introduce 28 Marineons by 2023.

BY JEONG JU-WON, YONHAP [jeong.juwon@joongang.co.kr]