Repair of metallic airframe components using fibre-reinforced polymer (FRP) composites

This chapter discusses the repair of metallic aircraft structures with bonded composite patches or reinforcements. Aspects discussed include key materials aspects, including pre-bonding surface preparation and patch application procedures, and an analytical repair design approach, with experimental confirmation. The difficult issue of the certification of bonded repairs to critically damaged primary aircraft structures is discussed. This results from the inability of conventional non-destructive testing to detect weak adhesive bonds. Two approaches to alleviate this difficulty are proposed: structural health monitoring and proof testing. Finally, two applications, one from the United States and the other Australian, are described followed by a conclusion on limitations and lessons learned.