Japan has grounded its fleet of V-22 Osprey aircraft again after an incident last Sunday in which one of the hybrid helicopters unexpectedly banked and hit the ground while trying to take off.

The V-22 was participating in the joint US military exercise Keen Sword and was carrying 16 passengers, including three US service members. During take-off, “it became unstable as it rocked from side to side and the left wing, the lower part of the aircraft came into contact with the ground and part of the aircraft was damaged, so the flight was aborted ”, Japan’s Ground stated. The Self-Defense Forces said in a statement.

It was the first major incident for Japan’s V-22 fleet since the Osprey crash last November, which killed eight Air Force Special Operations Command service members and led to a month-long grounding of the entire fleet in both ​Japan as well as in the United States.

The aircraft resumed flight operations earlier this year, but the Osprey’s use remains controversial, particularly in Okinawa, where residents have questioned its safety record.

The Osprey in last Sunday’s incident managed to land and no one was injured, however Japan will keep its fleet of more than a dozen V-22s on the ground while it investigates the incident, Defense Minister Gen. Nakatani told reporters last week.

“We believe there is no safety issue with the Ospreys, although ensuring flight safety is a prerequisite for aircraft operations,” Nakatani said.