Update – Boeing 777

Boeing believes the 777 is an attractive replacement choice for DC-10 and L. 1011 operators, offering twin engine economy. greater capacity and a more flexible choice of seating configurations. It will also be an all new, ultra modern aircraft, offering the latest in technology to take it into the somewhat difficult and changing operating environment of the 21st century. Certainly United-the 777 launch customer-ordered its 34 777s (plus 34 options) to provide a replacement for its current DC-10 fleet, and will operate the 777 largely on its extensive US domestic services. The aircraft’s second customer, All Nippon Airways, will replace its L. 1011 trijets on domestic services with 400 seat 777s, while A340s will fly longer, international routes. Similarly, American Airlines has expressed interest in acquiring the 777 for domestic routes to replace its 49 DC-10s, while British Airways is interested in replacing its 25 ageing L. 1011s with such an aircraft. Without doubt, a major selling point of the Boeing 777 is its capacity, which is as great (if not greater) than the older generation trijets. The 63. 77m (209ft 1in) long. 6. 2m (20ft 4in) wide fuse-lage houses a cabin area well capable of carrying 360-390 passengers in from six to ten abreast seating arrangements; in fact, the cabin is to be equipped with eight Type A 107 x 189cm (42 x 74in) doors to permit the aircraft to carry 440 passengers in a high density, all economy, ten abreast seating configuration. This makes the 777 a very flexible airliner, able to take full advantage of market needs for both a high density, shorter range twin- jet for domestic routes (typical, for example of Japanese domestic and some US high volume sectors) or lower density seating for longer ranges, closer to what is presently the domain of the 747. To aid flexibility, provision is being made for rapid relocation of galleys, toilets and seats so that the aircraft may be reconfigured overnight to operate different services which require varied seat- ing and performance characteristics.

Whilst offering excellent seating capacity within the cabin, the 777 also provides high capacity under the floor with the capability to carry 32 LD-3 containers (most of which will be utilised for carrying passengers’ luggage) and 19. 3m of (680ft) of bulk loaded cargo, for a total under-floor volume of 126. 6m (5,740ft). An optional under-floor 2. 45 x 3. 18m crew rest room capable of accommodating six rest bunks will also be offered.

Thus the 777 offers exceptionally high capacity for a twinjet, so that it compares very favourably with its two main competitors, the MD-11/12X and A330/340. The standard 777 offers in effect the same seating capacity as the Airbus A330 (undoubtedly the aircraft which is most in competition with the 777) and the A340-300, the latter of which is scheduled to enter service during 1992. Both Airbus aircraft offer standard, two class seating arrangements for 335 passengers, with an option for 440 seats in the maximum density seating arrangement. A more typical three class configuration enables the 777 to carry 298 passengers (24 first class in six abreast, 56 business in seven abreast and 218 economy in mainly 9 abreast) whilst the A330 accommodates just three fewer, the economy configuration being eight abreast. Like the 777, the A330 can also hold 32 LD-3 containers under the cabin plus bulk loaded cargo.

The MD-11’s 6m (19ft 9in) wide fuselage offers a standard three class configuration for 323 passengers and the ability to carry more luggage and cargo, though its additional engine places it outside the classic A330/777 twinjet competition and makes it less of a comparable aircraft, though Boeing and MDC officials do see the MD11/12X as an important competitor. For airlines seeking high capacity the planned MD-12X trijet would no doubt offer higher capacity in both passengers and cargo, though at this early stage of the project it is not possible to compare any figures.

Up front on the flight deck, the 777 offers several new innovations for Boeing aircraft. The 777 will be the first Boeing airliner to feature fly-by-wire technology, in a cockpit based on the 747-400 cockpit rather than that of the 767. Honeywell International have been contracted to develop the 777 flight system and will supply the Airplane Information Management System (AIMS), which will consist of dual integrated cabinets containing all necessary central processing and input/output hardware to perform flight management, central maintenance, aircraft condition monitoring, digital communications management, engine data interface and data conversion. Several new, latest technology features will be incorporated, such as flat panel displays which will replace the current generation cathode ray tubes (CRTs), a navigation system utilising new ring laser gyros, which are some 60% smaller than current gyros, and Boeing’s ARINC 629 digital databus, which may even include an electronic data library to provide onboard, electronic access to maintenance and flight manuals. The 777 therefore offers airlines the latest in technology, Boeing having accepted that fly-by-wire technology is the way to go. Also incorporating several new innovations is the aircraft’s primary structure, in particular the wings. The most noticeable and talked about feature is the optional folding wing mechanism, a first for an aircraft of this size. The unprecedented (for a commercial airliner) wings’ 60. 05m (196ft 11in) span is optimised for range and takeoff performance, but when Boeing first discussed the 777 with airline representatives it became apparent that the aircraft had to be able to utilise current airport bridges, something that the 777 may have trouble doing at many airports. Thus Boeing engineers came up with the idea of a folding wing mechanism; the folding mechanism was initially to be incorporated in all 777s, but the aircraft is now available either with the mechanism or with a standard, solid wing. The advantage of not having the folding mechanism is a weight saving of about 1,410kg (3,100lb), though without it there is less flexibility for airport use. A third option is to have the folding wing structure installed in the locked down position, though without the activating system, which can be installed later if desired; the weight penalty in this configuration is 1,045kg (2,300lb). United at this stage will only have the basic wing, with no folding mechanism.

Boeing engineers are naturally proceeding with development of the folding wing with much care and several safety measures have already been decided: a full scale development aircraft is to be tested prior to airline service; a two part cockpit control mechanism will be installed, one to arm and the other to activate the folding wing: two mechanical locks will secure the eight hydraulically actuated pins which lock the wingtip in the down position; an electronic means of checking the wingtips is to be installed, as the flight crew will be unable to check these visually -lasers and television cameras are being discussed as possible checking devices; the folding mechanism itself to be isolated from all hydraulic and electronic power during flight.

The aircraft’s structure incorporates also an unprecedented use of composite materials. Boeing is actively moving away from the use of aluminium and lithium where possible, for composites offer weight savings and strength, and are easier to repair. Stron- ger, stiffer carbon fibre materials will be utilised in the horizontal and vertical tails, in the passenger cabin floor beams and in the wings. Another weight saving feature is the aircraft’s two six wheel main undercarriage trucks, chosen because it is a lighter option than two four wheel main trucks plus a two wheel centre unit, which was also proposed.

Boeing is remaining neutral on the question of engines for the 777. The three main engine rivals – Pratt & Whitney, General Electric and Rolls-Royce are vying for 777 powerplant contracts with an updated version of its successful PW4000 series and the other two manufacturers with new design engines.

The first round of the competition was won by Pratt & Whitney when United chose the PW4073 to power its aircraft, a blow to GE whose engine was designed specifically for the 777 market. The PW4073 will be rated at 84,500lb (United has chosen a 73,100lb option), close to the 85,000-90,000lb thrust range of the competing GE90 and RR Trent 800. All three engines will offer the 777 similar performance and with their larger diameter fans the PW4073 features a 2. 85m (112in) fan will offer reduced fuel burn and noise, both becoming increasingly important in the airline industry. The advantage of the P&W engine choice is that the GE90 and Trent still require extensive development, while the PW4073’s relative commonality with other PW4000 series engines may be of benefit to airlines’ maintenance programs, as is believed to be the case with United.

Performance figures at this stage remain only predictions, though Boeing is confident that they will prove accurate – if not being bettered. Initial figures are for the standard 777 to have a maximum takeoff weight (MTOW) of 229,520kg (506,000lb) with a range capability of 4,150nm (7,700km), carrying 364 passengers in a two class configuration; the structural capability of the aircraft allows for an optional MTOW of 233,600kg (515,000lb), this being the option which United has chosen because it will allow the airline to carry more passengers on its domestic routes, and with extended twin operations (ETOPS) would give the aircraft a Honolulu/Chicago capability. In the standard 229,520kg MTOW option, the aircraft would typically be able to fly comfortably from Tokyo to such ports as Brisbane, Honolulu, Vancouver and all of south-east Asia; from London the aircraft could fly to most east coast US cities, the Middle East and Bombay in India. This compares with the Airbus A330, which Jane’s lists as having a lower MTOW of 208,000kg (458,560lb) but a higher range of 4,610nm (8,540km) with 335 passengers. The 777 is stated as having a typical Mach. 83 cruise speed, the A330 Mach. 82.

But while the standard 777 figures are admirable, they will promptly be bettered and the aircraft will prove even more attractive to long range operators. Plans are already underway for extended range (ER) versions to be introduced, as early as 18 months after the initial 777 enters United Airlines service. To aid future development such as the production of ER variants, Boe- ing has designed several key components and structures of the 777-such as the wing and the main landing gear-to accommodate growth versions. Thus it is able to offer an ER version so soon into the new airliner’s official design and development stage. The new longer range version, which at this stage is known as the “B” aircraft (the initial model is the “A”), is aimed to carry 300-320 passengers about 6,400nm (11,860), making it suitable for all transatlantic and most Pacific routes. This B aircraft- which no doubt will be called the 777ER as is the fashion with extended range airliners-will reportedly have a basic 267,620kg (590,000lb) MTOW. Such an aircraft would be capable of servicing, for instance, Melbourne/Tokyo and would compare with planned Airbus A330 versions, though range and operating speed would be below that of the A340 series.

A further ER variant under long term planning is the lower capacity “C” model, which would push the 777 design beyond the range of the 747-400 to about 7,800nm. Its lower capacity would probably preclude direct competition with the 747-400, though it would be a worthy, twin engined competitor to the Airbus A340 series. The design of such a variant is at this stage, however, long term, and may be pushing the 777 design to the limit. Other growth plans include the to-be-expected stretched versions which would be of maximum benefit in the high density Asian, European and US markets.

Thus the possibilities for the 777 design appear promising. However, prior to the aircraft entering service there remains much design and testing to be carried out. On the avionics side, the Boeing 757 testbed will be fully equipped with full fly-by-wire technology for avionics testing and demonstration flights. Four pre-production 777 prototypes will be constructed for standard certification testing, a very important program being the full testing of the aircraft’s folding wing mechanism to prove its feasi- bility to an airline industry which has naturally expressed some apprehension about the unusual concept.

Boeing will also be working hard to have ETOPS approval granted as soon as possible, so that its customer airlines can gain full advantage from the aircraft’s range capabilities. The company intends to use the test aircraft and early production aircraft to perform 1,000 fight cycles with each airframe/engine combination to ensure that all 777s will be 180 minutes ETOPS approved on delivery.

Production plans for the 777 are well underway, with several firms chosen to build specific components. A major surprise has perhaps been the extent to which Japanese industry- which holds an 8-10% risk sharing investment stake in the project-will be involved. A recently signed memorandum of understanding gives Japanese companies responsibility for building almost the entire fuselage except Section 41, the nose and cockpit area which Boeing traditionally builds in-house. Mitsubishi will build Sections 46 (the large fuselage section aft of the wing) and 48 (which includes the pressure bulk head and the tail cone), while Kawasaki and Fuji Heavy Industries will be responsible for Section 43 (fuselage section forward of the wing) and the wing cen- tre section. Meanwhile, Australian companies are also expected to benefit from the 777 program, ASTA already holding an MoU for rudder construction. Interestingly, the rudder will be so large that specially constructed containers will be required to transport the finished products from Melbourne to the USA.

With such a promising design and a well planned flight test program, Boeing are sure to have in the 777 a real winner, well able to compete with its prime opposition. With the aircraft having already achieved its important first sale to a US carrier (United) and an international carrier (All Nippon Airways) the 777 is well on its way. No doubt the aircraft will have a considerable order backlog by the time of the first delivery (planned for May 1995) and the Boeing 777 design will have entered the airline skies, where it is expected to remain for a half century or more.