Boeing 777
The Boeing 777, commonly referred to as the Triple Seven, is an American long-range wide-body airliner developed and manufactured by Boeing Commercial Airplanes. The 777 is the world's largest twinjet and the most-built wide-body airliner.
The jetliner was designed to bridge the gap between Boeing's other wide body airplanes, the twin-engined 767 and quad-engined 747, and to replace aging DC-10 and L-1011 trijets. Developed in consultation with eight major airlines, the 777 program was launched in October 1990, with an order from United Airlines. The prototype aircraft rolled out in April 1994, and first flew that June. The 777 entered service with the launch operator United Airlines in June 1995. Longer-range variants were launched in 2000, and first delivered in 2004. Over 2,300 Boeing 777 aircraft have been ordered, with over 70 operators worldwide.
The Triple Seven can accommodate a ten–abreast seating layout and has a typical 3-class capacity of 301 to 368 passengers, with a range of. The jetliner is recognizable for its large-diameter turbofan engines, raked wingtips, six wheels on each main landing gear, fully circular fuselage cross-section, and a blade-shaped tail cone. The 777 became the first Boeing airliner to use fly-by-wire controls and to apply a carbon composite structure in the tailplanes.
The original 777 with a maximum takeoff weight of was produced in two fuselage lengths: the initial 777-200 was followed by the extended-range -200ER in 1997; and the longer 777-300 in 1998. These have since been known as 777 Classics and were powered by General Electric GE90, Pratt & Whitney PW4000, or Rolls-Royce Trent 800 engines. The extended-range 777-300ER, with a MTOW of, entered service in 2004, the longer-range 777-200LR in 2006, and the 777F freighter in 2009. These second-generation 777 variants have extended raked wingtips and are powered exclusively by GE90 engines. In November 2013, Boeing announced the development of the third generation 777X, featuring composite wings with folding wingtips and General Electric GE9X engines, and slated for first deliveries in 2027.
, Emirates was the largest operator with a fleet of 163 aircraft., more than 60 customers have placed orders for 2,457 777s across all variants, of which 1,776 have been delivered. This makes the 777 the best-selling wide-body airliner, while its best-selling variant is the 777-300ER with 833 delivered. The airliner initially competed with the Airbus A340 and McDonnell Douglas MD-11; since 2015, it has mainly competed with the Airbus A350. First-generation 777-200 variants are to be supplanted by Boeing's 787 Dreamliner., the 777 has been involved in 31 aviation accidents and incidents, including five hull loss accidents out of eight total hull losses with 542 fatalities including 3 ground casualties.
Development
Background
In the early 1970s, the Boeing 747, McDonnell Douglas DC-10, and the Lockheed L-1011 TriStar became the first generation of wide-body passenger airliners to enter service. In 1978, Boeing unveiled three new models: the twin-engine or twinjet Boeing 7N7 to replace its 727, the twinjet Boeing 7X7 to challenge the Airbus A300, and a trijet "777" concept to compete with the DC-10 and L-1011. The mid-size 757 and 767 launched to market success, due in part to 1980s' extended-range twin-engine operational performance standards regulations governing transoceanic twinjet operations. These regulations allowed twin-engine airliners to make ocean crossings at up to three hours distance from emergency diversionary airports. Under ETOPS rules, airlines began operating the 767 on long-distance overseas routes that did not require the capacity of larger airliners. The trijet "777" was later dropped, following marketing studies that favored the 757 and 767 variants. Boeing was left with a size and range gap in its product line between the 767-300ER and the 747-400.By the late 1980s, DC-10 and L-1011 models were expected to be retired in the next decade, prompting manufacturers to develop replacement designs. McDonnell Douglas was working on the MD-11, a stretched successor of the DC-10, while Airbus was developing its A330 and A340 series. In 1986, Boeing unveiled proposals for an enlarged 767, tentatively named 767-X, to target the replacement market for first-generation wide-bodies such as the DC-10, and to complement existing 767 and 747 models in the company lineup. The initial proposal featured a longer fuselage and larger wings than the existing 767, along with winglets. Later plans expanded the fuselage cross-section but retained the existing 767 flight deck, nose, and other elements. However, airline customers were uninterested in the 767-X proposals, and instead wanted an even wider fuselage cross-section, fully flexible interior configurations, short- to intercontinental-range capability, and an operating cost lower than that of any 767 stretch.
Airline planners' requirements for larger aircraft had become increasingly specific, adding to the heightened competition among aircraft manufacturers. By 1988, Boeing realized that the only answer was a clean-sheet design, which became the twinjet 777. The company opted for the twin-engine configuration given past design successes, projected engine developments, and reduced-cost benefits. On December 8, 1989, Boeing began issuing offers to airlines for the 777.
Design effort
served as the Boeing 777 program's director of engineering, and then was promoted in September 1992 to lead it as vice-president and general manager. The design phase of the all-new twinjet was different from Boeing's previous jetliners; eight major airlines played a role in the 777 development. This was a departure from industry practice, where manufacturers typically designed aircraft with minimal customer input. The eight airlines that contributed to the design process became known within Boeing as the "Working Together" group. At the group's first meeting in January 1990, a 23-page questionnaire was distributed to the airlines, asking what each wanted in the design. By March 1990, the group had decided upon a baseline configuration: a cabin cross-section close to the 747's, capacity up to 325 passengers, flexible interiors, a glass cockpit, fly-by-wire controls, and 10 percent better seat-mile costs than the Airbus A330 and McDonnell Douglas MD-11.The development phase of the 777 coincided with United Airlines replacement program for its aging DC-10s. On October 14, 1990, United became the launch customer with an order for 34 Pratt & Whitney-powered 777s valued at US$11 billion and options for 34 more. The airline required that the new aircraft be capable of flying three different routes: Chicago to Hawaii, Chicago to Europe, and non-stop from Denver, a hot and high airport, to Hawaii. ETOPS certification was also a priority for United, given the overwater portion of United's Hawaii routes. In late 1991, Boeing selected its Everett factory in Washington, home of 747 production, as the 777's final assembly line. In January 1993, a team of United developers joined other airline teams and Boeing designers at the Everett factory. The 240 design teams, with up to 40 members each, addressed almost 1,500 design issues with individual aircraft components. The fuselage diameter was increased to suit Cathay Pacific, the baseline model grew longer for All Nippon Airways, and British Airways' input led to added built-in testing and interior flexibility, along with higher operating weight options.
The 777 was the first commercial aircraft to be developed using an entirely computer-aided design process. Each design drawing was created on a three-dimensional CAD software system known as CATIA, sourced from Dassault Systèmes and IBM. This allowed engineers to virtually assemble the 777 aircraft on a computer system to check for interference and verify that the thousands of parts fit properly before the actual assembly process—thus reducing costly rework. Boeing developed its high-performance visualization system, FlyThru, later called IVT to support large-scale collaborative engineering design reviews, production illustrations, and other uses of the CAD data outside of engineering. Boeing was initially not convinced of CATIA's abilities and built a physical mock-up of the nose section to verify its results. The test was so successful that additional mock-ups were canceled. The 777 was completed with such precision that it was the first Boeing jetliner that did not require the details to be worked out on an expensive physical aircraft mock-up. This helped the design program to limit costs to a reported $5 billion.
Testing and certification
Major assembly of the first aircraft began on January 4, 1993. On April 9, 1994, the first 777, number WA001, was rolled out in a series of 15 ceremonies held during the day to accommodate the 100,000 invited guests. The first flight took place on June 12, 1994, under the command of chief test pilot John E. Cashman. This marked the start of an 11-month flight test program that was more extensive than testing for any previous Boeing model. Nine aircraft fitted with General Electric, Pratt & Whitney, and Rolls-Royce engines were flight tested at locations ranging from the desert airfield at Edwards Air Force Base in California to frigid conditions in Alaska, mainly Fairbanks International Airport. To satisfy ETOPS requirements, eight 180-minute single-engine test flights were performed. The first aircraft built was used by Boeing's nondestructive testing campaign from 1994 to 1996, and provided data for the -200ER and -300 programs.At the successful conclusion of flight testing, the 777 was awarded simultaneous airworthiness certification by the US Federal Aviation Administration and European Joint Aviation Authorities on April 19, 1995.
Entry into service
Boeing delivered the first 777 to United Airlines on May 15, 1995. The FAA awarded 180-minute ETOPS clearance for the Pratt & Whitney PW4084-engined aircraft on May 30, 1995, making it the first airliner to carry an ETOPS-180 rating at its entry into service. The first commercial flight took place on June 7, 1995, from London Heathrow Airport to Dulles International Airport near Washington, D.C. Longer ETOPS clearance of 207 minutes was approved in October 1996.On November 12, 1995, Boeing delivered the first model with General Electric GE90-77B engines to British Airways, which entered service five days later. Initial service was affected by gearbox bearing wear issues, which caused British Airways to temporarily withdraw its 777 fleet from transatlantic service in 1997, returning to full service later that year. General Electric subsequently announced engine upgrades.
The first Rolls-Royce Trent 877-powered aircraft was delivered to Thai Airways International on March 31, 1996, completing the introduction of the three power plants initially developed for the airliner. Each engine-aircraft combination had secured ETOPS-180 certification from its entry into service. By June 1997, orders for the 777 numbered 323 from 25 airlines, including launch customers that had ordered additional aircraft. Operations performance data established the consistent capabilities of the twinjet over long-haul transoceanic routes, leading to additional sales. By 1998, the 777 fleet had approached 900,000 flight hours. Boeing states that the 777 fleet has a dispatch reliability above 99 percent.