747SR
Responding to requests from Japanese airlines for a high-capacity aircraft to serve domestic routes between major cities, Boeing developed the 747SR as a "short range" variant of the 747-100 with lower fuel capacity and greater payload capability. With increased economy class seating, up to 498 passengers could be carried in early versions and more than 550 in later models.[72] The 747SR had an "economic design life objective" of 52,000 flights during 20 years of airline operation, compared to 20,000 flights in 20 years for the standard 747. The initial 747SR model, the -100SR, had a strengthened body structure and undercarriage to accommodate the added stress accumulated from a greater number of takeoffs and landings.[107] Extra structural support was built into the wings, fuselage, and the landing gear along with a 20% reduction in fuel capacity.[108]
The initial order for the -100SR, four aircraft for Japan Air Lines (JAL, later Japan Airlines), was announced on October 30, 1972; rollout occurred on August 3, 1973, and the first flight took place on August 31, 1973. The type was certified by the FAA on September 26, 1973, with the first delivery on the same day. The -100SR entered service with JAL, the type's sole customer, on October 7, 1973, and typically operated Japanese domestic flights.[38] Seven -100SRs were built from 1973 and 1975, each with a 520,000-pound (240,000 kg) MTOW and Pratt & Whitney JT9D-7A engines derated to 43,000 pounds-force (190,000 N) of thrust.[109]
Following the -100SR, Boeing produced the -100BSR, a 747SR variant with increased takeoff weight capability. Debuting in 1978, the -100BSR also incorporated structural modifications for a high cycle-to-flying hour ratio; a related standard -100B model debuted in 1979. The -100BSR first flew on November 3, 1978, with first delivery to All Nippon Airways (ANA) on December 21, 1978. A total of twenty -100BSRs were produced for ANA and JAL.[110] The -100BSR had a 600,000 lb MTOW and was powered by the same JT9D-7A engines used on the -100SR. ANA operated the type on domestic Japanese routes with 455 or 456 seats until retiring its last aircraft on March 10, 2006.[111]
In 1986, two -100BSR SUD models, featuring the stretched upper deck (SUD) of the -300, were produced for JAL.[112] The type's maiden flight occurred on February 26, 1986, with FAA certification and first delivery on March 24, 1986.[113] JAL operated the -100BSR SUD with 563 seats on domestic routes until their retirement in the third quarter of 2006. While only two -100BSR SUDs were produced, in theory, standard -100Bs can be modified to the SUD certification.[110] Overall, 29 747SRs were built,[2] including seven -100SR, 20 -100BSR, and two -100BSR SUD models.