Project Number: A2931

Project Title: Aluminum Etch Pit Removal Advancement

Period of Performance: JUL24 – JUL26

This Center for Naval Metalworking (CNM) initiative aims to develop and implement a material peening solution to mitigate the effects of etch pits on various F-35 components resulting from the anodization process. Some F-35 flight-critical structures exhibit reduced fatigue life due to the anodizing process applied to aluminum during manufacturing. This process includes three key steps prior to assembly: fluorescent penetrant inspection (with a pre-penetrant etch to remove potential smeared metal), chemical conversion coating application, and anodization. These steps have resulted in etch pitting, increasing the likelihood of crack initiation sites and subsequently reducing fatigue life. These pits manifest over time after the aircraft has accrued flight hours. Initially, pits are not noticeable during production, as a certain level of stress is required for their formation. Etch pit removal must be conducted on the aircraft (e.g., metallic structure, bulkheads) and will be carried out as a depot modification/retrofit task within sustainment. Current removal methods employ a combination of mechanical and hand sanding, which are neither reliable nor repeatable. Early investigations into commercial off-the-shelf (COTS) solutions are steering the integrated product team (IPT) towards a needle peening approach.

This project is expected to result in five-year savings of approximately $1.0M.

The Aluminum Etch Pit Removal Advancement project is expected to be implemented at Lockheed Martin facility during 1Q FY27.