FedEx Corp. has ordered 24 more Boeing freighters, comprising 12 767Fs and 12 777Fs.   The Memphis-based cargo carrier said the 767Fs will be delivered between June 2019 and May 2022, while the 777Fs will be delivered between June 2020 and May 2025. The total order is valued at $6.6 billion at list prices.   FedEx is already the largest operator globally of both aircraft types, operating 57 767Fs and 34 777Fs, according to Aviation Week Intelligence Network fleet ...