Lockheed Martin [LMT] has resumed delivering F-35 Lightning IIs to the U.S. Department Defense after a corrosion problem halted those shipments for over a month.

The “acceptance hold,” which was put in place March 29, was lifted May 1, DoD’s F-35 Joint Program Office (JPO) said May 8.

The JPO and Lockheed Martin both indicated that they have reached an agreement to fix the corrosion, which was caused by fastener holes not being properly treated during production. 

The Air Force's F-35A conventional variant. Photo: Air Force.
The Air Force’s F-35A conventional-takeoff-and-landing variant. (Air Force photo)

The JPO, “along with the U.S. services, international allies and Lockheed Martin, have implemented a comprehensive corrective action plan to make the necessary repairs to all aircraft while minimizing impact to operations,” the office said in a statement. “The majority of aircraft will be complete within 24 months, with the remaining aircraft completed as their availabilities/modification timing allows.”

The JPO and Lockheed Martin did not disclose who will pay for the repairs. Navy Vice Adm. Paul Grosklags, head of Naval Air Systems Command, testified before the House Armed Services Committee’s tactical air and land forces panel April 12 that the company was responsible for the “mistake” and should cover the cost of fixing it.

Lockheed Martin said it continued F-35 production during the delivery pause and that it remains on track to meet its goal of delivering 91 jets this year.