F-35 Structural Component Requires Redesign

Thirty Air Force F-35A and 34 Marine Corps F-35B strike fighters built early in the aircraft’s production run will require modification to achieve their full 8,000-flight-hour design lives, according to the F-35 Joint Program Office. That’s because program engineers identified a shortfall with a structural component in their wings, known as the forward root rib, according to a JPO statement. It’s an aluminum part located where the leading edge of the wing meets the strike fighter’s fuselage. The engineers came across this issue initially during an analytical assessment of the F-35 airframe’s fatigue life. During more recent F-35A full-scale durability testing, a crack emerged in the forward root rib after more than 2,800 hours that was consistent with the analytical predictions. The JPO and prime contractor Lockheed Martin have drafted retrofit plans for the 64 early aircraft and they’ve created a redesigned root rib that they’ll incorporate for both variants at the beginning of Lot 5 production. The root rib is not an issue with the Navy’s F-35C variant. The JPO said durability testing helps identify structural issues early on “to avoid costly sustainment issues later in the life of the aircraft.”