Lockheed Martin recently paused deliveries of its F-35 Lightning II fighter jets to the U.S. Air Force amid concerns it could explode during a lightning strike.
“During routine depot maintenance at Ogden Air Logistics Complex, it was discovered an F-35A had damage to a tube in the Onboard Inert Gas Generation System (OBIGGS). Lockheed Martin initiated a delay in deliveries while we verified F-35 production is conforming to specifications with regard to OBIGGS installation. We are working with the F-35 Joint Program Office (JPO) on a root cause corrective action investigation to determine next steps, as it appears this anomaly is occurring in the field after aircraft delivery,” Lockheed Martin said in a statement provided to American Military News.
“We are currently delivering F-35 aircraft and the service’s continue flight and combat operations,” Lockheed Martin added. “As a safety precaution, the JPO recommended to unit commanders that they implement a lightning flight restriction for the F-35A, which restricts flying within 25 miles of lightning or thunderstorms.”
A company memo, provided to Congress and first reported by Bloomberg News, indicated problems with a tubing used to circulate inert gas in the fighter jets fuel tanks to prevent explosions. Lockheed Martin has since resumed deliveries of its fighter jets, but recommended pilots are restricted from flying “within 25 miles of lightning or thunderstorms” as a safety precaution while the company works to resolve the problem with the Defense Department’s F-35 program office.
The inert gas system, known as the Onboard Inert Gas Generation System (OBIGGS), is employed on the Air Force variant of the Lightning II fighter. The OBIGGS is used to prevent vapors in the fuel tank from combusting if the aircraft is struck by lightning.
The flaw in OBIGGS was identified in 14 of 24 of the Air Force model fighter jets that underwent a recent inspection.
“Inspection results to date have been worse than anticipated,” the memo said. The memo further suggested the root cause of the problem “is suspected to be” parts wearing out too fast instead of flawed installation.
“Lockheed Martin initiated a delay in deliveries while we verified F-35 production is conforming to specifications with regard to OBIGGS installation,” Lockheed Martin said in a statement provided to Military.com. “We are working with the F-35 Joint Program Office on a root cause corrective action investigation to determine next steps, as it appears this anomaly is occurring in the field after aircraft delivery.”
The Air Force has plans to buy 1,763 jets, the most of any of the participating military branches, including the U.S. Navy and Marine Corps. The Air Force variant is reportedly the most popular version among the F-35 program’s international partners.
The program is estimated at about $398 billion, making it the largest Pentagon program. Business Insider reported the F-35 program is projected to cost around $1 trillion over its 50 year service life.
The F-35 program office is reportedly withholding some payments to Lockheed Martin which will be directed “to the delivery of the key analysis and engineering improvements necessary to resolve this deficiency.”
This is not the first time there have been problems reported with the F-35’s OBIGGS system. A 2012 Pentagon F-35 program report, detailing problems dating back to 2009, determined “The system is not able to maintain fuel tank inerting through some critical portions of a simulated mission profile.”
In that case, the Pentagon report recommended a similar policy of avoiding thunderstorms, citing “lightning induced fuel tank explosions.”
The first instance of flight restrictions were removed in 2014 following a redesign to the OBIGGS system.
Lightning strikes on aircraft are statistically rare. The Federal Aviation Administration told Military.com that such strikes only occur about once per year.