page_title: Boeing 747
section_title: Development and testing
hierarchical_section_title: Boeing 747 / Development / Development and testing
caption_attribution_description: English: The Boeing 747, being displayed to the public for the first time
context_page_description: The Boeing 747 is a large, long–range wide-body airliner and cargo aircraft manufactured by Boeing Commercial Airplanes in the United States.
  After introducing the 707 in October 1958, Pan Am wanted a jet 2½ times its size, to reduce its seat cost by 30% to democratize air travel. In 1965, Joe Sutter left the 737 development program to design the 747, the first twin aisle airliner. In April 1966, Pan Am ordered 25 747-100 aircraft and in late 1966, Pratt & Whitney agreed to develop its JT9D, a high-bypass turbofan.
  On September 30, 1968, the first 747 was rolled out of the custom-built Everett Plant, the largest building in the world by volume.
  The first flight took place on February 9, 1969 and the 747 was certified in December of that year. It entered service with Pan Am on January 22, 1970; it was the first airplane dubbed a "Jumbo Jet".
  The 747 is a quadjet airliner, initially powered by JT9D turbofan engines, then GE CF6 and Rolls-Royce RB211 engines for the original variants. With a ten-abreast economy seating, it typically accommodates 366 passengers in three travel classes.
context_section_description: Before the first 747 was fully assembled, testing began on many components and systems. One important test involved the evacuation of 560 volunteers from a cabin mock-up via the aircraft's emergency chutes. The first full-scale evacuation took two and a half minutes instead of the maximum of 90 seconds mandated by the Federal Aviation Administration (FAA), and several volunteers were injured. Subsequent test evacuations achieved the 90-second goal but caused more injuries. Most problematic was evacuation from the aircraft's upper deck; instead of using a conventional slide, volunteer passengers escaped by using a harness attached to a reel. Tests also involved taxiing such a large aircraft. Boeing built an unusual training device known as "Waddell's Wagon" (named for a 747 test pilot, Jack Waddell) that consisted of a mock-up cockpit mounted on the roof of a truck. While the first 747s were still being built, the device allowed pilots to practice taxi maneuvers from a high upper-deck position.
  On September 30, 1968, the first 747 was rolled out of the Everett assembly building before the world's press and representatives of the 26 airlines that had ordered the airliner. Over the following months, preparations were made for the first flight, which took place on February 9, 1969, with test pilots Jack Waddell and Brien Wygle at the controls and Jess Wallick at the flight engineer's station. Despite a minor problem with one of the flaps, the flight confirmed that the 747 handled extremely well. The 747 was found to be largely immune to "Dutch roll", a phenomenon that had been a major hazard to the early swept-wing jets.
  During later stages of the flight test program, flutter testing showed that the wings suffered oscillation under certain conditions. This difficulty was partly solved by reducing the stiffness of some wing components. However, a particularly severe high-speed flutter problem was solved only by inserting depleted uranium counterweights as ballast in the outboard engine nacelles of the early 747s. This measure caused anxiety when these aircraft crashed, for example El Al Flight 1862 at Amsterdam in 1992 with 282 kilograms (622 lb) of uranium in the tailplane (horizontal stabilizer).
  The flight test program was hampered by problems with the 747's JT9D engines. Difficulties included engine stalls caused by rapid throttle movements and distortion of the turbine casings after a short period of service. The problems delayed 747 deliveries for several months; up to 20 aircraft at the Everett plant were stranded while awaiting engine installation. The program was further delayed when one of the five test aircraft suffered serious damage during a landing attempt at Renton Municipal Airport, site of the company's Renton factory. On December 13, 1969 a test aircraft was being taken to have test equipment removed and a cabin installed when pilot Ralph C. Cokely undershot the airport's short runway. The 747's right, outer landing gear was torn off and two engine nacelles were damaged. However, these difficulties did not prevent Boeing from taking a test aircraft to the 28th Paris Air Show in mid-1969, where it was displayed to the public for the first time. The 747 received its FAA airworthiness certificate in December 1969, clearing it for introduction into service.
  The huge cost of developing the 747 and building the Everett factory meant that Boeing had to borrow heavily from a banking syndicate. During the final months before delivery of the first aircraft, the company had to repeatedly request additional funding to complete the project. Had this been refused, Boeing's survival would have been threatened. The firm's debt exceeded $2 billion, with the $1.2 billion owed to the banks setting a record for all companies. Allen later said, "It was really too large a project for us." Ultimately, the gamble succeeded, and Boeing held a monopoly in very large passenger aircraft production for many years.
caption: The prototype 747 was first displayed to the public on September 30, 1968.
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