A U.S. military helicopter made an emergency landing at Kumamoto Prefecture's main airport on Wednesday afternoon with no casualties or air traffic disruption reported, the Defense Ministry said.
An oil cooling system apparently malfunctioned on the UH-1 multipurpose helicopter, forcing it to land to avoid an accident, according to the ministry. An AH-1 attack chopper that was flying with the UH-1 also landed at the airport.
The two helicopters are based at the U.S. Marine Corps' Air Station Futenma in Okinawa Prefecture, according to a Japanese government source.
Kumamoto Airport is used by both civilian and Self-Defense Forces aircraft. The U.S. military aircraft has been parked in an area managed by the SDF, the ministry said.
A number of incidents involving U.S. military aircraft have occurred in Japan recently, fueling safety concerns.
A Futenma-stationed helicopter of the same UH-1 type made an emergency landing on a sandy beach on a small islet of Okinawa in January. In December, a window fell from a CH-53E large transport helicopter as it was flying over an elementary school just outside the Futenma base. No one was injured in those incidents.