A US Air Force F-35A fighter jet caught fire while preparing for take-off at an air base in Florida, prompting Pentagon to ground all 26 F-35As while the incident is being investigated.
The fire of the Lockheed Martin-manufactured jet started in the rear area where the engine is located. However, it is not clear whether the engine was directly involved in the accident.
Engine maker Pratt & Whitney, a unit of United Technologies, said it was aware of the incident and stood ready to assist in the Air Force investigation.
The pilot of the affected aircraft aborted the take-off immediately and was not injured during the incident. The fire was immediately extinguished.
The incident came just days before a group of F-35 B-model jets are due to fly to Britain for the jet's international debut. One US defence official said it was too soon to say whether the fire would delay those plans or affect them in any way.
"Safety is paramount, and all F-35A flight operations have been temporarily suspended at Eglin as they investigate the nature of the incident," said Pentagon’s spokesman Joe DellaVedova.
This is the second incident that has affected F-35 flights in recent weeks. The US military ordered mandatory inspections of all 97 F-35 fighter jets earlier this month after a Marine Corps F-35 B-model jet suffered an oil leak in flight.
The incident was resolved quickly, and all but three jets returned to flight status within days. Those three jets are being repaired to deal with a faulty part, the F-35 spokesman said.
It was not immediately clear whether the fire would trigger fleet-wide inspection orders for all three models of the F-35.
Lockheed is building three models of the new warplane for the US military: a conventional take-off version for the Air Force, a short take-off and vertical landing version for the Marine Corps, and a carrier-based version for the Navy.
Britain helped fund development of the radar-evading jet, along with seven other countries: Australia, Norway, Italy, Denmark, the Netherlands, Turkey and Canada. Japan, Israel and South Korea have also placed orders for the warplane.
News of the fire also overshadowed a new report from the Pentagon's chief weapons buyer that showed the projected cost of retrofits required for the jet had dropped to $1.65 billion as of February 2014, from $1.75 billion a year earlier.
It said Lockheed was working closely with the F-35 program office to reduce the time required to implement design changes into the production line, which was helping to lower the cost.