Continued airworthiness of composite repairs to primary structures for military aircraft

The paper discusses policy and procedures for the use of damage tolerance methods for ensuring the continued airworthiness of (composite) structural repairs to military aircraft. In this work the focus is on repairs to principal structural elements (PSE) and structurally significant items (SSI). A modified form of the current FAA two stage evaluation and approval process is proposed. In this process the first stage is based on static structural strength considerations, to keep the aircraft down time to a minimum, and the second stage requires a full damage tolerance evaluation to be performed. The proposed approval process also includes a requirement to prepare a suitable in-service inspection programme.