The incident happened Oct. 27 at Marine Fighter Attack Training Squadron 501, a fleet replacement squadron for the Marine Corps consisting of 20 F-35B aircraft. One of the aircraft experienced a fire in the weapons bay while conducting a training mission over Beaufort, 1st Lt. John Roberts, a spokesman for 2nd Marine Aircraft Wing, told Military.com.
"The aircraft landed safely and there were no injuries sustained," he said. "An investigation is ongoing and we will provide updates as they are available."
No estimate of damage caused by the fire was available. The incident was listed by the Naval Safety Center as a Class A mishap, meaning damage totalled $2 million or more on the $100 million aircraft.
The squadron didn't observe any kind of grounding or operational pause as a result of the mishap, Roberts said.
The F-35 program has suffered several setbacks due to aircraft catching fire, though previous incidents involved the Air Force's F-35A conventional take-off and landing variant.
In June 2014, an F-35A caught fire upon takeoff at Eglin Air Force Base, Florida, prompting the Defense Department to ground the entire F-35 fleet as it investigated the incident. This move forced the Marine Corps to postpone what was to have been the F-35B's international debut at the Farnborough International Airshow that summer.
The damage to the aircraft in that incident came to more than $50 million and was determined to have been caused by a rotor arm that detached and came through the aircraft's upper fuselage, cutting fuel and hydraulic lines in its trajectory.
More recently, in September, an F-35A from the 61st Fighter Squadron caught fire in the aft section of the aircraft after its engine was started, forcing the pilot to exit the aircraft.
In an unrelated issue, the Air Force grounded 15 F-35As the same month due to failing coolant tube insulation.
For the Marine Corps, this incident comes at a crucial time for the aircraft, as the first operational F-35B squadron, Marine Fighter Attack Squadron 121, prepares to forward-base from Yuma, Arizona to Japan in January, ahead of a sea deployment in the Pacific early the following year. The aircraft is now completing its third and final round of at-sea developmental tests aboard the amphibious assault ship USS America off the coast of San Diego, and is expected to complete them later this month.