Boeing 777-200

The Boeing 777 is a family of long-range wide-body twin-engine jet airliners developed and manufactured by Boeing Commercial Airplanes. It is the world's largest twinjet and has a typical seating capacity for 314 to 451 passengers, with a range of 5,235 to 9,500 nautical miles (9,695 to 17,594 km). Commonly referred to as the "Triple Seven", its distinguishing features include the largest-diameter turbofan engines of any aircraft, six wheels on each main landing gear, fully circular fuselage cross-section and a blade-shaped tail cone.Developed in consultation with eight major airlines, the 777 was designed to replace older wide-body airliners and bridge the capacity difference between Boeing's 767 and 747. As Boeing's first fly-by-wire airliner, it has computer-mediated controls. It was also the first commercial aircraft to be designed entirely with computer-aided design.

The 777 is produced in two fuselage lengths as of 2014. The original 777-200 variant entered commercial service in 1995, followed by the extended-range 777-200ER in 1997. The stretched 777-300, which is 33.25 ft (10.1 m) longer, followed in 1998. The longer-range 777-300ER and 777-200LR variants entered service in 2004 and 2006 respectively, while the 777F, a freighter version, debuted in February 2009; these variants all feature General Electric GE90 engines and extended raked wingtips. The earlier 777-200, -200ER and -300 versions are equipped with GE90, Pratt & Whitney PW4000, or Rolls-Royce Trent 800 engines. The 777-200LR is the world's longest-range airliner, able to fly more than halfway around the globe, and holds the record for the longest distance flown non-stop by a commercial aircraft.
The 777 first entered commercial service with United Airlines on June 7, 1995. It has received more orders than any other wide-body airliner; as of March 2016, 60 customers had placed orders for 1,895 aircraft of all variants, with 1,384 delivered.The most common and successful variant is the 777-300ER with 635 delivered and 800 orders;Emirates operates the largest 777 fleet, with 144 passenger and freighter aircraft as of July 2015.The 777 has been involved in five hull losses as of October 2015; the Asiana Airlines Flight 214 accident in July 2013 was its first fatal crash in 18 years of service.

The 777 ranks as one of Boeing's best-selling models. Airlines have acquired the type as a comparatively fuel-efficient alternative to other wide-body jets and have increasingly deployed the aircraft on long-haul transoceanic routes. Direct market competitors include the Airbus A330-300, newly launched Airbus A350 XWB, and the out-of-production A340 and McDonnell Douglas MD-11. The 787 Dreamliner, which entered service in 2011, shares design features with the 777. In November 2013, Boeing announced the development of upgraded 777-8 and 777-9 variants, collectively named 777X, featuring composite wings and GE9X engines and further technologies developed for the 787. The 777X series is planned to enter service by 2020.

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 Boeing 757 to replace its venerable 727, the twin-engine 767 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 (ETOPS) 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 approaching retirement age, prompting manufacturers to develop replacement designs.McDonnell Douglas was working on the MD-11, a stretched and upgraded successor of the DC-10, while Airbus was developing their A330 and A340. In 1986, Boeing unveiled proposals for an enlarged 767, tentatively named 767-X, to target the replacement market for first-generation wide-bodies like 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.

Airline customers were unimpressed with 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 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 new design, which became the 777 twinjet.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

The design phase for the new twinjet was different from Boeing's previous commercial jetliners. For the first time, eight major airlines – All Nippon Airways, American Airlines, British Airways, Cathay Pacific, Delta Air Lines, Japan Airlines, Qantas, and United Airlines – had a role in the 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 first group meeting in January 1990, a 23-page questionnaire was distributed to the airlines, asking what each wanted in the design. By March 1990, Boeing and the airlines had decided upon a basic design 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 A330 and MD-11. Boeing selected its Everett factory in Washington, home of 747 production, as the 777's final assembly site.

On October 14, 1990, United Airlines became the 777's launch customer when it placed an order for 34 Pratt & Whitney-powered aircraft valued at US$11 billion with options on an additional 34.The development phase coincided with United's replacement program for its aging DC-10s. United 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 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 designed entirely by computer.Each design drawing was created on a three-dimensional CAD software system known as CATIA, sourced from Dassault Systemes and IBM.This lets engineers assemble a virtual aircraft, in simulation, to check for interference and verify that the thousands of parts fit properly—thus reducing costly rework.Boeing developed their own high-performance visualization system, FlyThru, later called IVT (Integrated Visualization Tool) 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.

Production and testing

The production process included substantial international content, an unprecedented level of global subcontracting for a Boeing jetliner, later exceeded by the 787. International contributors included Mitsubishi Heavy Industries and Kawasaki Heavy Industries (fuselage panels), Fuji Heavy Industries, Ltd. (center wing section), Hawker de Havilland (elevators), and Aerospace Technologies of Australia (rudder). An agreement between Boeing and the Japan Aircraft Development Corporation, representing Japanese aerospace contractors, made the latter risk-sharing partners for 20 percent of the entire development program.The initial 777-200 model was launched with propulsion options from three manufacturers, General Electric, Pratt & Whitney, and Rolls-Royce, giving the airlines their choice of engines from competing firms. Each manufacturer agreed to develop an engine in the 77,000 lbf (340 kN) and higher thrust class (a measure of jet engine output) for the world's largest twinjet.

Aircraft factory. Rectangular building with six doors, one of which is open to reveal an emerging airliner. The background is a forest; small vehicles and taxiways surround the factory.

An Air India Boeing 777-200LR is rolled out at the Boeing Everett Factory

To accommodate production of its new airliner, Boeing doubled the size of the Everett factory at the cost of nearly US$1.5 billion to provide space for two new assembly lines. New production methodologies were developed, including a turn machine that could rotate fuselage subassemblies 180 degrees, giving workers access to upper body sections.Major assembly of the first aircraft began on January 4, 1993.By the start of production, the program had amassed 118 firm orders, with options for 95 more from 10 airlines.Total investment in the program was estimated at over US$4 billion from Boeing, with an additional US$2 billion from suppliers.

On April 9, 1994, the first 777, line 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 engineswere 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 U.S. Federal Aviation Administration (FAA) and European Joint Aviation Authorities (JAA) on April 19, 1995.

Entry into service

Airliner takeoff. The jet's nose is angled upwards as it lifts above the runway, with landing gear still deployed.

The first Boeing 777-200 in commercial service, United Airlines' N777UA, taking off from Amsterdam Airport Schiphol in 2005.

Boeing delivered the first 777 to United Airlines on May 15, 1995.The FAA awarded 180-minute ETOPS clearance ("ETOPS-180") 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 powerplants initially developed for the airliner. Each engine-aircraft combination had secured ETOPS-180 certification from the point of entry into service. By June 1997, orders for the 777 numbered 323 from 25 airlines, including satisfied 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 (rate of departure from the gate with no more than 15 minutes delay due to technical issues) above 99 percent.

Initial derivatives

Airliner final approach. Side view of jet descending in the sky, with landing gear completely extended.

Air New Zealand 777-200ER on final approach

After the original model, Boeing developed an increased gross weight variant of the 777-200 with greater range and payload capability. Initially named 777-200IGW, the 777-200ER first flew on October 7, 1996, received FAA and JAA certification on January 17, 1997, and entered service with British Airways on February 9, 1997. Offering greater long-haul performance, the variant became the most widely ordered version of the aircraft through the early 2000s. On April 2, 1997, a Malaysia Airlines -200ER named "Super Ranger" broke the great circle "distance without landing" record for an airliner by flying eastward from Boeing Field, Seattle to Kuala Lumpur, a distance of 10,823 nautical miles (20,044 km), in 21 hours and 23 minutes.

Following the introduction of the -200ER, Boeing turned its attention to a stretched version of the airliner. On October 16, 1997, the 777-300 made its first flight. At 242.4 ft (73.9 m) in length, the -300 became the longest airliner yet produced (until the A340-600), and had a 20 percent greater overall capacity than the standard length model. The -300 was awarded type certification simultaneously from the FAA and JAA on May 4, 1998, and entered service with launch customer Cathay Pacific on May 27, 1998.

From the program's start, Boeing had considered building ultra-long-range variants. Early plans centered on a 777-100X proposal,a shortened variant of the -200 with reduced weight and increased range,similar to the 747SP. However, the -100X would have carried fewer passengers than the -200 while having similar operating costs, leading to a higher cost per seat By the late 1990s, design plans shifted to longer-range versions of existing models. A more powerful engine in the 100,000 lbf (440 kN) and higher thrust class was required, leading to talks between Boeing and engine manufacturers. General Electric offered to develop the GE90-115B engine, while Rolls-Royce proposed developing the Trent 8104 engine. In 1999, Boeing announced an agreement with General Electric, beating out rival proposals. Under the deal with General Electric, Boeing agreed to only offer GE90 engines on new 777 versions.

Production updates and improvements

In 2010, Boeing announced plans to increase production from 5 aircraft per month to 7 aircraft per month by mid-2011, and 8.3 per month by early 2013 Complete assembly of each 777-300ER requires 49 days. In November 2011, assembly began on the 1,000th 777, a -300ER model for Emirates; which was rolled out in March 2012. In late 2011, the FAA assigned a common type rating to the 787 and 777, allowing pilots qualified on either aircraft to operate both models, due to related design features. The smaller 787 was the first stage of a replacement aircraft initiative called the Boeing Yellowstone Project. Reportedly, the 777 could eventually be replaced by a new aircraft family, Yellowstone 3, which would draw upon technologies from the 787.

Aircraft takeoff. Quarter view of aircraft ascending in the sky, with landing gear still deployed.

All Nippon Airways 777-300ER taking off

By the late 2000s, the 777 was facing increased potential competition from Airbus' planned A350 XWB and internally from proposed 787 variants,both airliners that promise fuel efficiency improvements. As a consequence, the 777-300ER received an engine and aerodynamics improvement package for reduced drag and weight. In 2010, the variant further received a 5,000 lb (2,300 kg) maximum zero-fuel weight increase, equivalent to a higher payload of 20–25 passengers; its GE90-115B1 engines received a 1–2.5 percent thrust enhancement for increased takeoff weights at higher-altitude airports.[107] More changes were targeted for late 2012, including possible extension of the wingspan,[107] along with other major changes, including a composite wing, new powerplant, and different fuselage lengths.[107][108][109] Emirates was reportedly working closely with Boeing on the project, possibly being the launch customer for new 777 versions.[110] China Airlines ordered ten 777-300ER aircraft to replace 747-400s on routes between Taipei and Los Angeles and New York City, telling Aviation Week and Space Technology that the 777-300ER's per seat cost is about 20% lower than the 747's costs (varying due to fuel prices).[111] Four of the 777 aircraft were already flying as of February 2015.

Mindful of the long time required to bring the 777X to the market, Boeing continued to develop improvement packages which improve fuel efficiency, as well as lower prices for the existing product. As of February 2015, the backlog of undelivered 777s totals 278 aircraft, representing just under three years of current production at 8.3 aircraft per month,causing Boeing to ponder the 2018-2020 time frame. In January 2015, United Airlines ordered 10 Boeing 777-300ERs, normally costing around $150 million each but paid around $130 million, a discount to bridge the production gap to the 777X.Boeing has worked with General Electric to offer a 2% improvement in fuel efficiency to new aircraft beginning in 2016. GE will improve the fan module and the high pressure compressor stage-1 blisk in the GE-90-115 turbofan, as well as reduce clearances between the tips of the turbine blades and the shroud during cruise. These improvements, of which the latter is the most important and was derived from work to develop the 787, will, GE says, lower fuel burn by 0.5%. Boeing's wing modification will deliver the remainder. Boeing stated that every 1% improvement in the 777-300ER's fuel burn translates into being able to fly the aircraft another 75 nautical miles on the same load of fuel, or add ten passengers or 2,400 lb of cargo to a "load limited" flight. In March 2015, additional details of the improvement package were published in Aviation Week & Space Technology. The 777-300ER will shed 1,800 lb. Boeing will replace the fuselage crown with tie rods and composite integration panels, similar to those used on the 787. New flight control software will eliminate the need for the tail skid by keeping the tail off the runway surface regardless of the extent to which pilots command the elevators. Boeing is also redesigning the inboard flap fairings to reduce drag by reducing pressure on the underside of the wing. The outboard raked wingtip will have a divergent trailing edge, a "poor man's airfoil" (Boeing's description) originally developed for the McDonnell Douglas MD-12 project. Another change involves elevator trim bias. These changes would not only increase fuel efficiency, they would allow airlines to add 14 additional seats to the airplane, increasing per seat fuel efficiency by 5%

Design

Aircraft belly section. Close view of engines, extended landing gear and angled control flaps.

Engines, extended slats, flaps, and landing gear of an American Airlines 777-200ER

Boeing introduced a number of advanced technologies with the 777 design, including fully digital fly-by-wire controls, fully software-configurable avionics, Honeywell LCD glass cockpit flight displays, and the first use of a fiber optic avionics network on a commercial airliner.Boeing made use of work done on the cancelled Boeing 7J7 regional jet, which utilized similar versions of the chosen technologies. In 2003, Boeing began offering the option of cockpit electronic flight bag computer displays. In 2013, Boeing announced that the upgraded 777X models would incorporate airframe, systems, and interior technologies from the 787.

Fly-by-wire

In designing the 777 as its first fly-by-wire commercial aircraft, Boeing decided to retain conventional control yokes rather than change to sidestick controllers as used in many fly-by-wire fighter aircraft and in many Airbus airliners.Along with traditional yoke and rudder controls, the cockpit features a simplified layout that retains similarities to previous Boeing models. The fly-by-wire system also incorporates flight envelope protection, a system that guides pilot inputs within a computer-calculated framework of operating parameters, acting to prevent stalls, overspeeds, and excessively stressful maneuvers. This system can be overridden by the pilot if deemed necessary. The fly-by-wire system is supplemented by mechanical backup.

Airframe and systems

Aircraft landing gear. Six wheel gear on the ground, with attachment assembly and gear door leading up to the aircraft belly.

The six-wheel undercarriage of a Boeing 777-300

The wings on the 777 feature a supercritical airfoil design that is swept back at 31.6 degrees and optimized for cruising at Mach 0.83 (revised upward after flight tests to Mach 0.84).The wings are designed with increased thickness and a longer span than previous airliners, resulting in greater payload and range, improved takeoff performance, and a higher cruising altitude. The wings also serve as fuel storage, with longer-range models able to carry up to 47,890 US gallons (181,300 L) of fuel. This capacity allows the 777-200LR to operate ultra-long-distance, trans-polar routes such as Toronto to Hong Kong.In 2013, a new wing made of composite materials was introduced for the upgraded 777X, with a wider span and design features based on the 787's wings.

Large folding wingtips, 21 feet (6.40 m) long, were offered when the 777 was first launched, to appeal to airlines who might use gates made to accommodate smaller aircraft, but no airline purchased this option. Folding wingtips reemerged as a design feature at the announcement of the upgraded 777X in 2013. Smaller folding wingtips of 11 feet (3.35 m) in length will allow 777X models to use the same airport gates and taxiways as earlier 777s. These smaller folding wingtips are less complex than those proposed for earlier 777s, and internally only affect the wiring needed for wingtip lights.

The airframe incorporates the use of composite materials, which comprise nine percent of its original structural weight (all models outside the 777-8 and 777-9). Elements made from composite material include the cabin floor and rudder. The main fuselage cross-section is circularand tapers rearward into a blade-shaped tail cone with a port-facing auxiliary power unit. The aircraft also features the largest landing gear and the biggest tires ever used in a commercial jetliner. The six-wheel bogies are designed to spread the load of the aircraft over a wide area without requiring an additional centerline gear. This helps reduce weight and simplifies the aircraft's braking and hydraulic systems. Each tire of a 777-300ER six-wheel main landing gear can carry a load of 59,490 lb (26,980 kg), which is heavier than other wide-bodies such as the 747-400.The aircraft has triple redundant hydraulic systems with only one system required for landing.A ram air turbine –a small retractable propeller which can provide emergency power– is also fitted in the wing root fairing.

Interior

Airliner cabin. Rows of seats arranged between two aisles. Each seatback has a monitor; light shines from the sidewalls and overhead bins.

Economy class cabin of Etihad Airways 777-300ER in a 3-3-3 layout

The original 777 interior, also known as the Boeing Signature Interior, features curved panels, larger overhead bins, and indirect lighting.Seating options range from six abreast in first class up to 10 across in economy. The 777's windows were the largest of any current commercial airliner until the 787, and measure 15-inch (380 mm) by 10-inch (250 mm) in size (all models outside the 777-8 and -9) The cabin also features "Flexibility Zones", which entails deliberate placement of water, electrical, pneumatic, and other connection points throughout the interior space, allowing airlines to move seats, galleys, and lavatories quickly and more easily when adjusting cabin arrangementsSeveral aircraft have also been fitted with VIP interiors for non-airline use. Boeing designed a hydraulically damped toilet seat cover hinge that closes slowly.

Airliner cabin. Rows of seats arranged between two aisles.

EVA Air 777-300ER business class in 1-2-1 herringbone layout

In 2003, Boeing introduced overhead crew rests as an option on the 777.Located above the main cabin and connected via staircases, the forward flight crew rest contains two seats and two bunks, while the aft cabin crew rest features multiple bunks. The Signature Interior has since been adapted for other Boeing wide-body and narrow-body aircraft, including 737NG, 747-400, 757-300, and newer 767 models, including all 767-400ER models.The 747-8 and 767-400ER have also adopted the larger, more rounded windows of the original 777.

In 2011, Flight International reported that Boeing is considering replacing the Signature Interior on the 777 with a new interior similar to that on the 787, as part of a move towards a "common cabin experience" across all Boeing platforms.With the launch of the 777X in 2013, Boeing confirmed that the aircraft would be receiving a new interior featuring 787 cabin elements and larger windows. Further details released in 2014 included re-sculpted cabin sidewalls for greater interior room, noise-dampening technology, and higher cabin humidity