The Pentagon will not lift restrictions on F-35A lightning after hardware and software

WASHINGTON – The most widely used version F-35 still can’t fly in lightning, and despite hardware and software modifications, the Pentagon has no way to lift current flight restrictions.

In June 2020, the Pentagon F-35 Joint Program Office imposed flight restrictions on the F-35A’s conventional takeoff and landing variant after damaged pipes were found in its key lightning protection system, the Onboard Inert Gas Generation System, or OBIGGS.

Air Force Times Earlier this year, it was reported that the program office could allow the fighter to begin flying within 25 miles of lightning after testing a fix to the OBIGGS system this summer. However, after evaluating the hardware and software upgrades, the JPO recommended maintaining the flight restrictions, according to Chief Petty Officer Matthew Olay, JPO’s F-35 spokesman.

“Due to additional discoveries made earlier this year, this update will provide an improvement, but not enough to remove the lightning restriction,” Olay told Breaking Defense. “Lightning restrictions will be lifted when all safety concerns are resolved or acceptably mitigated.”

The JPO declined to comment on what prompted the program office to maintain the flight restrictions, with Olay saying that “for reasons of operational security, the JPO will not comment on specific findings.”

It’s also unclear whether the program office has a plan for further improvements to OBIGGS or a timeline for the eventual lifting of the zipper restrictions. “The JPO continues to take steps to address all lightning limitation issues by all available means. The restrictions on zippers will be lifted when all safety issues are resolved or are reduced to an acceptable level,” Olai said without elaborating in response to questions.

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The F-35 relies on OBIGGS for safe flight in thunderstorms or other conditions where lightning is present. The system renders the plane’s fuel tanks inert by pumping nitrogen-enriched air inside, preventing the plane from exploding if the tanks are struck by lightning.

The F-35’s OBIGG system has been a headache for the Pentagon several times over the years Lockheed MartinThe lifespan of home-built aircraft — sometimes leading to jokes about the Lightning II aircraft not being able to fly its namesake. In the early 2010s, the Pentagon imposed flight restrictions on the F-35 after its independent weapons tester found that the fuel tanks were not getting enough nitrogen-enriched gas to render it completely inert. After OBIGGS was redesigned, the program office allowed the F-35 to fly near Lightning in 2014.

The latest problem was discovered in June 2020 during scheduled maintenance on the F-35A at the Hill Air Force Base Logistics Complex in Ogden, Utah. At the time, Bloomberg reported on a JPO memo describing inspections in which 14 of 24 F-35As were estimated to contain OBIGGS with damaged tubes.

The question was raised by the Pentagon temporarily suspend F-35 deliveries for a couple of weeks to rule out a problem with OBIGGS production, but supplies resumed after Lockheed confirmed it was installing the system correctly, with problems developing later after operational use, a Lockheed spokesman said at the time.

The program office began implementing a hardware modification in November 2021 that “replaces some of the OBIGGS pipes and fittings with a more robust design” that better withstands the vibrations that occur during flight, Olay said. A software improvement that notifies the pilot of a degraded OBIGGS system began rolling out in August 2022.

As of fiscal year 2022, the Air Force has about 375 F-35As, according to the service’s budget. The JPO declined to comment on how many of those aircraft have gone through the hardware upgrade process so far, citing operational safety concerns. However, all Model A’s will receive the upgraded hardware, “regardless of whether or not tube damage is detected,” Olay said. These modifications are occurring at the unit level and will be completed by 2025.

While flight restrictions remain in place — and fighter pilots avoid training during thunderstorms, regardless of the aircraft they’re flying — there have been cases where F-35 pilots have found themselves flying into bad weather and being struck by lightning.

As of late January 2022, F-35 units in the Air Force, Marine Corps, and Navy reported 15 lightning strikes that damaged F-35s operating in the air, according to Air Force Times.

In an incident on August 3, 2021, an F-35 was struck by lightning during flight, damaging the canopy and panels on its fuselage. The pilot was not injured, but the Air Force classified the event as a Class B accident, with the estimated cost of repairing the plane between $600,000 and $2.5 million, according to the report.