Rolls-Royce has signed an agreement with Air bp to supply the engine manufacturer with sustainable aviation fuel (SAF) for upcoming engine testing at three of its facilities.The aviation fuel will be a 10% sustainable aviation fuel blend and will be supplied to Rolls-Royce's facilities in Derby and Bristol, United Kingdom and Dahlewitz, Germany. These three testing centers each cover engines for different aerospace sectors -- Derby: civil aviation; Bristol: defense; and Dahlewitz: business aviation.Air bp will also provide fuel for the very first run of the Rolls-Royce UltraFan demonstrator engine, which will be carried out entirely on 100% SAF let this year. The manufacturer says this will be the largest aero engine in the world."This agreement delivers on a commitment we made that the fuel for testing and development is a 10% sustainable aviation fuel blend by 2023," said Chris Cholerton, President -- Civil Aerospace. "We want to encourage the use of SAF throughout the aviation industry and this agreement is an example of the firm commitments fuel producers require to support their continued production investment."Rolls-Royce has previously committed to ensuring that its Trent and business aviation engines are compatible with 100% SAF by 2023, although they are already certified and ready to operate on a 50% SAF blend.