Boeing's only trijet is powered by Pratt & Whitney JT8D low-bypass turbofans below a T-tail, one on each side of the rear fuselage and a center one fed through an S-duct. It shares its six-abreast upper fuselage cross-section and cockpit with the 707. The 133 ft (40.6m) long 727-100 typically carries 106 passengers in two classes over 2,250 nmi (4,170 km), or 129 in a single class. Launched in 1965, the stretched 727-200 flew in July 1967 and entered service with Northeast Airlines that December. The 20 ft (6m) longer variant typically carries 134 passengers in two classes over 2,550 nmi (4,720 km), or 155 in a single class. Besides the airliner accommodation, a freighter and a Quick Change convertible version were offered. 727-200F Advanced A freighter version of the 727-200 Advanced became available in 1981, designated the Series 200F Advanced. Powered by Pratt & Whitney JT8D-17A engines, it featured a strengthened fuselage structure, an 11 ft 2 in (3.40 m) by 7 ft 2 in (2.18 m) forward main deck freight door, and a windowless cabin. Fifteen of these aircraft were built, all for Federal Express. This was the last production variant of the 727 to be developed by Boeing; the last 727 aircraft completed by Boeing was a 727-200F Advanced.