High velocity oxygen fuel (HVOF) coatings have been in development for chrome replacement for aerospace applications and implemented for many applications over the past couple of decades. Now that these coatings have become common for newly manufactured parts, the need for repair and overhaul coating thicknesses beyond 0.254 mm (0.010 inch) for rework that traditionally would have thick chrome and nickel build-ups with chrome caps has started to develop. This requirement has been identified for high strength steel landing gear applications and will follow most likely in similar aircraft applications such as flap and slat tracks, actuators and other aircraft support structure. This paper will discuss the development and qualification requirements necessary, and related concerns in order to replace these thick repair coating applications with duplex coatings, or possibly with thick single coating applications that will meet the original design criteria for each part.

A commercial air carrier has replaced the chrome plating on line-of-sight landing gear installed on several aircraft with HVOF sprayed WC-Co-Cr coatings. Pending the results of ongoing testing and service evaluations, the carrier plans to switch to HVOF coatings on all line-of-site landing gear and possibly other structural and engine components. This paper discusses the infrastructure that will be necessary to build, qualify, and maintain a high-velocity oxyfuel spraying facility that will serve one of the largest fleets of aircraft in the world. Paper includes a German-language abstract.