The chief of the world's largest international airline, Sir Tim Clark has demanded that Boeing deliver Emirates a perfect 777X with engines thoroughly tested to the highest stress levels and meeting guarantees. "I am not interested in (fuel) improvement packages or later mods (modifications) and I insist on the engines being fully stressed in Dubai summer conditions," Sir Tim Clark said in an exclusive interview. "I want the 777X doing flight tests out of Dubai fully loaded in summer to really stress the engines." "Brand new engines always have problems but this time we will not accept anything less than guarantees." The 777X is powered by General Electric's GE9X engine which was certified in late September. READ: Emirates full fleet of 123 A380s back by 2022 The FAR (Federal Aviation Regulation) Part 33 certification involved eight test engines and was made up of 5,000 hours of flight tests and 8,000 cycles. The GE9X engine is designed to achieve 10 percent lower specific fuel consumption (SFC) compared to the GE90-115B and five percent better SFC than any other engine in its class. GE Aviation is also conducting another 3,000 cycles of additional ground testing on the GE9X engine to support Extended Operations (ETOPS) approval. Mr. Clark said that the delivery of the first 777X, the plane he once called "a peach",  is now slated for June 2022. "First, it was December 2019, then June 2020, then June 2021 now June 2022," said Mr. Clark. "The 737 MAX situation has derailed Boeing and now we have an entirely different FAA (Federal Aviation Authority) certification process. The FAA will be applying the microscope to the 777X and examining every aspect of the design and build." And Emirates is looking to the 777X as the flagship of its future and will come with the airline's new premium economy product. Boeing now has four 777X aircraft flying in the flight test program and is continuing to produce the aircraft and then store them to await the completion of the certification.