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Boeing 747 General Overview


From its first flight in 1969, the 747 was an airplane of superlatives: It was bigger, flew farther and carried more people than any other commercial airplane. Today, that's still true.

The latest model, the 747-400, can fly 420 passengers about 8,300 miles. The 747-400 has a two-pilot digital flight deck, a new interior, and is powered by stronger, more efficient engines. With its huge capacity, extended range and improved fuel efficiency, the 747-400 offers the lowest operating costs per seat of any commercial jetliner. In addition to the passenger version, the 747-400 is offered as a combi -- carrying passengers forward and cargo aft on the main deck -- as well as a domestic, high-capacity version.

Boeing continues to study airplanes capable of carrying more passengers than today's 747s. If sufficient market demand develops, Boeing will offer a larger airplane. However, near-term product-development efforts are focused on enhanced versions of the 767 and 777.

Aerodynamics and Structural Materials
The most noticeable aerodynamic improvement, designed to reduce fuel burn and extend the 747-400's range, is the 6-footlonger wing with a 6-foot-high winglet angled upward and slightly outward. The winglet provides the effect of having an even greater wingspan without outgrowing the standard airport slot. The wingtip extension and winglet offers a fuel mileage improvement of about 3 percent.

Graphite-epoxy materials, currently used on Boeing 737-300, 757 and 767 airplanes, have resulted in a durable and lightweight winglet. The composite and aluminum winglet saves 60 pounds (27 kg) per airplane compared to an all-aluminum structure.

The wing-to-body fairing has been recontoured for drag improvement. Additional efficiency is incorporated in newly designed nacelles and struts for the advanced engines, the General Electric CF6-80C2, Pratt & Whitney PW4000 or the Rolls-Royce RB211-524G, which provide a minimum 56,000 pounds of thrust.

An optional 3,300 U.S. gallon (12,490 L) fuel tank in the horizontal tail boosts the -400's range up to an additional 403 statute miles (350 nautical miles or 650 km), for long fuel capacity limited routes. The 747-400's 8,290 statute mile (7,200 nautical mile) range makes possible non-stop service with typical full (420) passenger, three-class payload on such routes as London-Tokyo, Singapore-London and Los Angeles-Sydney.

Use of advanced materials allows considerable structural weight reductions throughout the 747-400. Metal flooring previously used in the passenger cabin has been replaced by light, tough graphite composite floor panels.

Structural carbon brakes, offered on the 757 and 767, are standard on the 747-400. Technical advantages include improved energy absorption characteristics and wear resistance. Estimated weight savings, using the new brakes, on the -400's 16 main landing gear wheels is 1,800 pounds (816 kg).

Higher strength aluminum alloys with improved fatigue life, introduced on the 757 and 767, are now incorporated in the 747-400's wing skins, stringers and lower-spar chords, achieving a weight savings of approximately 4,200 pounds (1,900 kg).

Flight Deck
The 747-400 flight deck provides even more flexibility than the successful 757/767 design. The 747-300 three-crew member analog cockpit with electro-mechanical instruments was transformed into a fully digital, two-crew flight deck with cathode ray tube (CRT) displays.

Six 8-by-8-inch (200-by-200-mm) CRTs display airplane flight control, navigation, engine and crew alerting functions. The larger CRTs allow more information to be displayed with fewer instruments. Flight deck lights, gauges and switches have been reduced from 971 (in the 747-300) to 365 on the -400. Flight crew work load is designed to be one-half to one-third that of former 747 models.

Automatic or manual display switching is used as backup in the event of an individual CRT failure. The engine indicating and crew alerting system (EICAS) can call up the status or schematics of various systems at any time on one of the CRTs.

Crews can now obtain an update of the aircraft's mechanical condition while in flight. Previously the information was only available to maintenance workers when the airplane was parked.

Interior Design
Interiors of the 747-400 have been redesigned to improve passenger convenience and appeal. Ceiling and sidewall panels have been recontoured with new, lighter weight materials that provide an open, airy look. Passenger stowage capacity has grown to 15.9 cubic feet (0.45 cubic meters) in each 60-inch (152 cm) outboard stowage bin or 2.95 cubic feet (0.082 cubic meters) per passenger.

New laminate materials are designed to meet Boeing fireworthiness goals. A new thermoplastic blend reduces smoke and toxicity levels in the event of fire, and upper-deck ceiling panels are made of improved polyester and phenolic sheet molding materials instead of polyester.

Interior flexibility permits airline operators to relocate class dividers and galley and lavatory modules more quickly to serve market requirements. Lavatory installation is simplified by a vacuum waste system and additional locations for galleys and lavatories are available. These "quick change features" allow major rearrangement within 48 hours, while seats and compartments can be changed overnight.

A revised 747-400 air distribution system increases the main deck cabin air distribution zones from three to five, and ventilation rates can be regulated based on passenger density in each zone.

For the first time on any airliner, an optional overhead cabin crew rest area uses space in the rear of the fuselage above the aft lavatories. This area, which can be configured for eight bunks and two seats, provides privacy as well as comfort for off-duty flight attendants. By using this compartment, 10 more profit seats are available on the main deck of the aircraft.

Increased Range and Flexibility
An 875,000-pound (396,890 kg) maximum takeoff weight option is being offered, a 75,000-pound (34,020 kg) increase over the baseline -400. This provides an increased range over the 747-300 of 1,000 nautical miles (1,150 statute miles or 1,850 km) with the additional tail fuel.

A new 1,450-horsepower auxiliary power unit (APU) provides an estimated 35 percent to 40 percent reduction in fuel consumption, better air pressurization performance on hot days, higher electrical output and reduced noise levels over the prior APU. These units, mounted in the rear fuselage of 747s, supply pressurized air for air conditioning and engine starting while the airplane is on the ground plus electrical power to operate lights and other requirements during stops. The new APU also can be retrofitted to earlier 747s.

In early 1989 airline customers were offered even more flexibility in the 747 family with the introduction of the 747-400 Combi. The Combi is "two airplanes in one," carrying passengers forward and cargo aft on the main deck. Because cargo and passengers can be loaded simultaneously, the Combi adapts easily to meet changing passenger and cargo traffic demands. KLM was the first to purchase the 747-400 Combi.

The 747-400 high-capacity (569 passengers) Domestic went into commercial service with Japan Airlines in the fall of 1991. This model incorporates structural improvements to accommodate the increased takeoff and landing cycles encountered in short-range intra-Japan operations.

An all-cargo version was added to this family when Air France announced an order for four 747-400 Freighters in Sept. 1989. Cargolux took delivery of the first Freighter in Nov. 1993.

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