Due to the increasing use of carbon fibre reinforced plastics (CFRP) in aircraft structures a growing demand for repair concepts can be observed. Today’s repair concepts are mainly focused on the refurbishment of parts at the manufacturer’s site in order to reduce waste. Additionally, specialised service providers travel on call to repair parts that are already installed. The next step to be undertaken is transferring the actual repair from the manufacturer to the airline thus further reducing an aircraft’s down time.

In order to allow the repair of damaged CFRP-parts at an aircraft maintenance hangar it is necessary to provide a repair concept that employs standardised repair-patches. These patches combine the ability to restore structural integrity and are easy to use. The quality of repair depends on the consistency of mechanical properties throughout the structure. Two factors play a key role - the contact-area between patch and part on one side and the patch lay-up sequence on the other. Using standardised repair patches it is not always possible to find a perfect match, neither in patch size nor in lay-up. Hence, the influence of different patch sizes, stiffness variations, surface treatments, and chamfer designs was investigated. Simulation was used to check on a variety of failure sizes and possible patch designs. Purposefully damaged parts were produced and repaired with patches of standardized design. The success of repair was evaluated through mechanical testing.