The Marine Corps’ jump-jet version of the F-35 Joint Strike Fighter suffered its first major mishap when a fire broke out in the weapons bay of an F-35B during a recent training flight, officials said.

The pilot was not injured and landed the plane safely at its home station of Marine Corps Air Station Beaufort in South Carolina, said 1st Lt. John Roberts, a spokesman for the 2nd Marine Aircraft Wing.

The incident happened on Oct. 27 and the F-35B was with Marine Fighter Attack Squadron 501, Roberts said Tuesday. An investigation into the matter is ongoing and it is too early to determine what may have caused the fire, he said.

Military.com first reported Monday about the fire aboard the F-35B, which can take off and land vertically.

This is the first Class A mishap for the F-35B, said Marine Corps spokeswoman Capt. Sarah Burns. Such mishaps involve loss of life or damage of more than $2 million.

With many of its legacy aircraft aging and worn out from years of war, the Marine Corps plans to buy 353 F-35Bs and 67 F-35Cs to replace its F/A-18 Hornets, EA-6B Prowlers and AV-8B Harrier II jets by fiscal 2032.

This is the second major incident for the F-35 program since September, when an Air Force F-35A caught fire during an exercise at Mountain Home Air Force Base, Idaho.

That fire happened shortly after the Air Force discovered that insulation for the F-35A’s coolant tubes had begun to disintegrate into the fuel tank, prompting the service tosuspend flight operations for 15 F-35As.

The F-35B does not have the same problem, said Mike Rein, a spokesman for prime contractor Lockheed Martin.

“The coolant tube issue only occurred on F-35A model,” Rein said Tuesday.