Lockheed Martin [LMT] has resumed delivering F-35 Lightning IIs to its U.S. and foreign customers after a production quality problem halted those transfers for a month.
The problem surfaced when a small amount of corrosion was found under a fuselage panel of an F-35A, the fighter jet's conventional-takeoff-and-landing variant, during routine maintenance at Hill Air Force Base in Utah, the company said in a statement Nov. 1.
After investigating the matter with the U.S. Department of Defense’s F-35 Joint Program Office (JPO), Lockheed Martin determined that a required primer coat was not being applied to fastener holes on certain panels and substructures. The primer is supposed to protect the aluminum holes against corrosion.
All F-35 deliveries were suspended from Sept. 21 to Oct. 20 while a corrective action plan was being developed.
The JPO and Lockheed Martin said the company has tweaked its production line, including work instructions, training and processes, to ensure primer is applied to all fastener holes on future airplanes. Fielded jets will receive the primer during routine maintenance.
“This is a production quality escape issue and, though it needs be corrected to prevent potential future corrosion, it does not pose a safety of flight risk to the F-35 fleet or affect current operations,” the JPO said in a statement.
Despite the temporary delivery suspension, Lockheed Martin said it still expects to meet its delivery goal of 66 F-35s by the end of 2017. It has delivered 54 jets so far this year.