The F-35A Lighting IIs can't fly within 25 miles of a storm due to a compromised ability to render their fuel tanksinert. The flight restriction was expected to be lifted over two years after it was issued. It hasn't
The prohibition on flight in proximity to storms has implications for F-35 training in places like Eglin Air Force Base in the Florida Panhandle.
The Air Force trains about 60 F-35A pilots annually at Eglin. If there was a storm 25 nautical miles from the base, takeoffs and landings would be stopped. In close proximity to training ranges, the same would hold.
The Air Force F-35 community is restricted. The F-35 Joint Program Office does not comment on any impact to flight operations due to security concerns.
The Program Office's policy of not commenting wouldn't stop the U.S. adversaries from figuring out how much of a hit the lightning problem puts in F-35 training. They could use the weather data to get a gauge.
A clever adversary could schedule tactical activities to coincide with bad weather in an area where F-35As might overwise be expected to fly with their electronic intelligence gathering systems. The flight restriction may have repercussions on the F-35A.
The restriction doesn't apply to the Marine Corps' F-35Bs or the Navy's F-35Cs. The program office gave no explanation as to why the Navy/Marine aircraft suffer the same problem as the F-35A.
If the F-35 is struck by lightning, the nitrogen-enriched air pumped into its fuel tanks will cause it to explode. The tubing and fittings inside the F-35's fuel tank don't function effectively over time due to the vibrations and may swing in temperature and pressure during flight.
During depot maintenance of the F-35A, there was damage to the OBIGGS system. Fourteen of 24 F-35As had damaged tubing. A decision was made as to whether the problem was caused by faulty production or not. This wasn't the case and the flights were restricted by the JPO.
The OBIGGS system was fixed by the Department of Defense and Lockheed. The fix involvedstrengthening a number of brackets associated with the tubes. The modifications would allow the tubes inside the fuel tank to be fixed in place more securely.
The Air Force Times reported in February that the F-35As would be able to fly near lightning without restriction by the summer. The restriction was not lifted. Despite the fixes, the prohibition on flying near lightning is still in effect.
Chief Olay explained to me that the F-35B and C variant have some of the same issues as the F-35A but have been able to alleviate them.
In July of 2021, the Marine Corps revealed that a pair of its F-35Bs were grounded in Japan after being hit by lightning during sorties. Olay did not say how the Navy and Marines are alleviating impact. The B and C models of the F-35 have different design and function.
The OBIGGS system for the F-35 was designed and built by a business unit within Cleveland-basedParker Hannifin. The F-35 variant had different performance requirements which drove different fuel and inerting system architectures according to the post. The system architectures were unique, butParker was able to use common hardware.
There is a possibility that the USAF F-35As can't operate near lightning. It is possible that another issue is present which is unrelated to OBIGGS. The F-35As flown by U.S. allies from Europe to Israel to Australia haven't been made public but logic would suggest their aircraft face the same issue, potentially complicating training on an international scale.
There is no specific plan or timetable for the return of F-35As to all-weather status. When all safety concerns are mitigated, lightning restrictions will be lifted.
According to the JPO, all F-35As will be upgraded by the year 2025. The software modification that notifies a pilot when the OBIGGS system is degraded began rolling out in August. It appears that the USAF will have to deal with lightning for at least two years.