The Boeing 747-400
Powerplants were the key to commercial aircraft capability, measured by payload, range, and performance, and all were incorporated in the 747-200B when the 63,000 thrust-pound Pratt and Whitney JT9D-7Q became available. First ordered by Northwest Orient, but quickly followed by Braniff, Japan Air Lines, Singapore Airlines, and Avianca, the version, introducing lighter nacelles, offered a two- to three-percent reduction in fuel consumption. Powered by the similarly-rated General Electric CF6-50E and Rolls Royce RB.211-524D turbofans, the aircraft was able to boast a new maximum takeoff weight of 833,000 pounds.
While an increased capacity variant had been considered during the 747 program’s earliest days, these higher-thrust engines paved the way for serious reconsideration now without the former need to sacrifice cargo loads or range for it.
Toward that end, studies completed in 1976 focused on a 23-foot fuselage stretch, attained by means of seven-frame forward and eight-frame aft insertions, along with a 27-foot upper deck increase, for a new mixed class passenger capacity of 570, as opposed to the previous 440. Yet depressed passenger demand during the late-1970s precluded the viability of this admittedly ambitious project and airline customer consensus pointed to a more modest stretch.
This took form as the 747SUD, or “stretched upper deck,” in the spring of 1980. Lengthened by some 23 feet, it incorporated 18 additional windows and two full-size, upward-opening doors with 45-foot-long evacuation slides. Although it carried an 8,000-pound, or two-percent, structural weight increase, the otherwise simplified modification increased its six-abreast accommodation from 32 to 69, reached by a new, straight, internal staircase that replaced the type’s signature spiral one.
Designated 747-300, it was offered as both a new-build version or a conversion of existing 747-200Bs, both of which factored into launch customer Swissair’s June 1980 order for four of the former and one of the latter. Powered by four 64,750 thrust-pound JT9D-7R4G2 engines, it first flew two years later, on October 5, and was type certified a year after that on March 4 at an 833,000-pound gross weight.
While the minimal change version offered a modest capacity increase, it introduced neither increased range nor any type of design enhancement.
747-400 Design and Development:
Several factors caused serious reconsideration of a more ambitious derivative of the 747 in the mid-1980s.
Sales, first and foremost, had been declining. The monthly production rate of seven airframes in 1979 had been reduced to a trickle of only one. Without revitalization, the program was likely to be terminated.
Currency and advancement, secondly, had not been maintained, a strategy that had kept the 727 and 737 programs alive with advanced versions, and the later, particularly, had spawned the Next Generation 737-300, -400, and -500 series.
Competition, thirdly, although not always on an even-keel basis, had begun to appear with step-change technology, as occurred with the DC-10-30 and -40, whose succeeding MD-11 introduced quieter, more fuel efficient engines and two-person digital cockpits. Airbus itself was about to unveil its own twin- and quad-engine A330 and A340 designs. The 747 appeared particularly outdated with its three-man, analogue cockpit, especially when measured against Boeing’s own new-technology narrow and widebody 757 and 767 offerings.
Finally, growth had shifted from the Atlantic to the Pacific, with unprecedented numbers of passengers and amounts of cargo being transported to China, Japan, and Korea.
What was needed was a modernized version of the venerable 747 with significant range to eliminate the intermediate stops in Alaska and Hawaii, yet not sacrifice payload. The remedy was initially envisioned as a version of the 747-300 with either Pratt and Whitney PW4000 or General Electric CF6-80C turbofans, an increased wingspan, and its resultantly greater wing integral fuel tank capacity.
Yet, most of the major, early 747 operators sought far more than these basic power and dimensional increases packaged in the proposed 747-300A, prompting Boeing to embark upon an extensive reassessment project so that the new version would be commensurate with late-20th century technology.
Devising, in fact, a five-point list to generate next-generation sales, it sought to incorporate state-of-the-art technology, considerably enhance the passenger cabin, increase the range by 1,000 miles, reduce fuel consumption by up to 37-percent over that of the original 747-100, and reduce operating costs by ten percent.
Designated 747-400 and announced in May of 1985, it was a significantly improved aircraft.
Although it retained the 231.10-foot overall length of all the previous standard versions and featured the stretched upper deck of the -300, it introduced a considerably modified wing. Built up of the 2000 copper and 7000 zinc series of aluminum alloys developed for the 757 and 767, which formed the torsion box’s upper and lower skins, and incorporating graphite composites, it featured both a six-foot span increase and six-foot winglets that were outwardly canted by 29 degrees and had a 60-degree sweepback. Eliminating the need for a greater span increase, these area-rule designed devices harnessed the vortex created by the upper and lower pressure differential remix at the tip, increasing area and lift, reducing drag, and retaining gate compatibility dimensions a greater stretch would not have achieved.
“Winglets,” according to Boeing, “are a new stabilization feature to compensate for wing and body structural changes.” They facilitated the transport of 40 more passengers 2,500 miles further.
While the ailerons, spoilers, and dual-section, triple slotted trailing edge flaps remained the same as those incorporated on previous 747 versions, an additional variable camber leading edge flap was installed, resulting in three inboard Krueger devices from the root to the inboard engines, five mid-wing ones between the powerplants, and the new total of six between the outboard one and the tip.
The construction materials increased the wing’s strength by between five and 13 percent, yet reduced aircraft weight by up to 5,500 pounds. Compared to the 195.8-foot span of the previous versions, the 747-400 had a 211.5 unfueled one or 213.0 one with full tanks, which caused a downward bend of the airfoil. Aspect ratio was 7.7 and area was 5,825 square feet.
Another 747-400 improvement was its powerplant. Because engine manufacturers had made significant progress in the design and development of advanced turbofans, particularly for long-range, widebody twins which were predicated upon increased reliability and thrust and decreased fuel consumption and noise, the latest 747 version was 40-percent quieter than its -300 series predecessor. As had occurred with the 747-200B, it was offered with poweprlants made by all three engine manufacturers.
The 56,750 thrust-pound Pratt and Whitney PW4056, for example, specified by launch customer Northwest Orient, featured single crystal turbine blades, full authority digital engine control (FADEC), a ten-percent high pressure compressor ratio increase, and a 27-percent greater high pressure rotor speed. It consumed seven percent less fuel than the earlier JT9D upon which it was based.
The 58,000 thrust-pound General Electric CF6-80C2B1F, first specified by KLM Royal Dutch Airlines, offered a four-stage low pressure compressor matched to the fan, a core airflow that increased from 276 to 340 pounds per second, and an overall pressure ratio of 30.4 to 1 produced by the 14-stage high pressure compressor. Like the PW4056, it was FADEC-equipped.
The Rolls Royce RB.211-524, featuring three-shaft, wide-chord blades, was offered in two versions: the 58,000 thrust-pound -524G and the 60,000 thrust-pound 524H. It was first ordered by Cathay Pacific.
All engines, regardless of type, were attached to redesigned, streamlined pylons.
The Pratt and Whitney Canada PW901A auxiliary power unit (APU), replacing the long-standard Allied Signal one for the first time, consumed 40 percent less fuel. It could maintain a 75-degree Fahrenheit cabin temperature while the aircraft was on the ground with a 100-degree external one.
Fuel, whose capacity varied between 53,985 and 57,285 US gallons for Pratt and Whitney and Rolls Royce engine-powered aircraft, and between 53,711 and 57,011 US gallons for General Electric powered ones, was stored in the fuselage center section and two main tanks per wing, along with reserve and vent surge tanks. Although minor modifications had been made to their plumbing and sensors, the 747-400’s major design feature was a 3,300-US gallon auxiliary tank in the 72-foot, 2.5-inch spanned horizontal tailplane, providing a 350 nautical mile increase. It was not, however, used for in-flight center-of-gravity variation.
Increased rudder authority, amending maximum deflection from a former 25- to a present 30-degrees, facilitated a ten-knot ground speed reduction in which it could maintain the effectiveness.
While the 747-400 retained the same five-truck, 18-wheel configuration of the earlier versions, it replaced the former steel brakes with carbon ones, which offered a 1,800-pound weight reduction, were rated for twice the number of landings, and cooled faster, increasing aircraft turn-around times. Larger tires necessitated a wheel diameter increase from 20 to 22 inches. Ai digital antiskid system was introduced.
Ice and rain protection encompassed total air temperature probes; window wipers, washers, and rain repellent; window heat; pitot-static probes on both sides; angle-of-attack sensors, again on both sides; wing anti-ice; and engine inlet cowl anti-ice.
Aircraft servicing points were many. Those on the fuselage included vacuum cleaning, oxygen, electrical, potable water, hydraulic, oil, air start, and air conditioning. Those on the wing encompassed the fuel vent, the gravity fuel port, the fuel itself, and the fuel control panel on the left wing underside.
Significant enhancements were made to the interior.
The cockpit, first and foremost, was transformed from a three- to a two-person one, with the fight engineer’s functions having been incorporated in an overhead panel and these were now automatically monitored.
Employing digital systems designed for the 757 and 767, it featured six eight-by-eight inch cathode ray tube (CRT) displays, consisting of the primary fight display (PFD) and the navigation display (ND) placed side-by-side in front of the captain and duplicated for the first officer, and two center engine indication and crew alerting system (EICAS) screens.
The pedestal between the two pilots contained the control display units (CDU’s), the fuel control switches, the parking brake lever, the radio communication panels, the audio control panels, the aileron and rudder control panel, the stabilizer trim indicator, the weather radar control panel, the transponder control panel, the autobrake selector panel, and the public address-interphone handset.
An extensive data base, subdivided into performance and navigation categories, replaced the performance manuals and navigation charts, and facilitated the rapid, extremely accurate calculations of any desired parameter in conjunction with the flight management computer (FMC).
Information was both enterable and retrievable by means of the control display unit keypads.
During cockpit setup, the lower of the two engine indicator and crew alerting system screens displayed the secondary engine data-that is, the N2 and N3 shaft speeds, vibration, fuel flow, and oil temperature, pressure, and quantity-while the upper continuously displayed the primary engine data, such as engine pressure ratio, the N1 fan speed, and the exhaust gas temperature (EGT). Yet enough screen space remained for additional aircraft status indications, including flap and undercarriage positions.
Compared to the 971 lights, gauges, and switches of the first generation 747’s analog cockpit, the current -400’s digital one featured only a third, or 365. The aircraft was certified for Category IIIB landings.
Boeing listed its fight deck avionics baseline capabilities as follows.
“8 x 8 integrated displays: air data, primary flight and navigation instruments; engine, subsystems, caution and warning alerts; systems status and synoptic (heads-down monitoring).
“Multipurpose control display unit (MCDU): primary interfaces – FMCS, standby nav (IRS), standby nav radio tuning; secondary interface – accesses CMCS, ACARS, AIDS, weight and balance.
“Advanced FMC software package: thrust management – autothrottle/thrust limit; altitude/speed flight profile intervention via AFDS MCP; Nav radio tuning – automatic and remote; worldwide nav data base capability; software improvements.
“Central maintenance computer system (CMCS): standardized subsystem bite with English language readout; interactive control of system LRU bite via MCDU; interfaces flight deck//avionic and associated airplane systems.
“Improved dispatch reliability: redundant control of mode functions for EFIS/EICAS/AFDS MCP; display function switching and triple EIFS/EICAS interface units.
“Digital audio control and radio communication systems.”
Aside from two observer seats, a windowless crew rest compartment, featuring one or two full-length bunks, reading lights, and fresh air vents, enabled extra pilots to attain legal rest periods on fights that could span up to 18 hours. A comparable, although much larger, cabin crew rest area, installed in the formerly unutilized rear roof from the last row of passenger seats to the rear pressure bulkhead and replacing the 747-300’s “Portakabin” one that had taken the place of up to 20 revenue-generating passenger ones, was accessible by a locked door, three-step, and vertical ladder entryway. Incorporating additional insulation and ceiling lighting to simulate day and night cycles, it was configured with varying numbers of bunks and sleeper seats.
The redesigned interior, which introduced an advanced widebody look, featured recontoured ceilings and sidewalls; concealed lighting; self-supporting ceiling panels; larger overhead side and center storage compartments; outboard, seat track lockable modular galleys; modular, vacuum flushable toilets, whose waste was stored in four rear tanks; and a digital in-flight entertainment system with seat-back monitors; and five main deck air conditioning zones with higher ventilation.
Inter-deck access, as had been provided on the 747-300, was via a straight stairway.
Class division, density, capacity, color, fabric, and decoration varied according to customer specification. A 416 tri-class configuration, for instance, entailed 23 first class seats at a 61-inch pitch, 80 business class ones at a 39-inch pitch, and 313 coach class ones at a 32-inch pitch. A dual-class cabin accommodating 497 entailed 42 first class and 455 coach seats. Five hundred twenty-four could be subdivided into 42 business class seats at a 42-inch pitch and 406 coach ones at a 32-inch pitch, with another 76 on the stretched upper deck, provisioned with its own galleys and lavatories.
Maximum main deck abreast seating in the four cabins behind the nose was ten, with two aisles, and six on the upper deck with a single aisle. Maximum, exit-limited passenger capacity was 624.
The 747-400’s lower deck hold volume of 6,035 cubic feet was subdivided into 5,190 cubic feet of unit loading device (ULD) space and 845 of bulk or loose-load space, facilitating the loading of 16 forward and 14 aft LD-3 containers or five forward and four aft 96-by-125-inch pallets.
As powered by the CF6-80C2 engine, it had a 390,700-pound operating weight, 144,300-pound payload capability, 535,000-pound zero-fuel weight, 384,824-pound fuel weight, a maximum takeoff weight that varied from 800,000 to 870,000 pounds, and a maximum landing weight that varied from 574,000 to 630,000 pounds. Range, at a long-range cruise speed with 412 passengers and reserves, was 7,300 nautical miles.
Construction of the first 747-400, registered N401PW, began in mid-1986 in Everett, by which time 49 aircraft had been ordered by Singapore, KLM, Lufthansa, Cathay Pacific, and British Airways. Northwest’s launch order, for ten, called for aircraft configured for 420 passengers. Major assembly occurred a little over a year later, in September, and the first roll-out, on January 26, 1988, entailed a dual-ceremony, dual-location event, since it marked the occasion of the first 737-400 rollout in Renton. Another 58 aircraft, by United and Air France, had been intermittently ordered.
The expected system glitches, along with the unexpected part and powerplant delivery delays, postponed the first flight of the PW4056-powered aircraft from March to April 29, 1988, followed by first General Electric and Rolls Royce examples in, respectively, June and August. The GE airframe set a new world gross weight record, leaving the runway at 892,450 pounds.
Certification, following a four-aircraft flight test program, was achieved on January 9, 1989. Delivered to Northwest 17 days later and entering domestic service between Phoenix and Minneapolis on February 9 for crew familiarization purposes, the first 747-400, powered by PW4056 turbofans, was placed in the Pacific-spanning skies it was intended for, from New York to Tokyo, on June 1.
Other first deliveries included those to KLM and Lufthansa, on, respectively, May 18 and May 23 with General Electric engines, and to Cathay Pacific on June 8 with Rolls Royce powerplants. On the August 17 delivery flight to Qantas, the type set a world distance record from London to Sydney, covering the 9,688 miles in 20 hours, eight minutes.
By May 25, 1990, the 747-400 had attracted 279 firm orders.
As had occurred with the basic 747, and particularly with its -200B series, Boeing offered several variants of the 747-400.
The first of these was the 747-400 Combi Featuring mixtures of main deck passenger and cargo loads, the latter in two aft zones, it incorporated a 120- by 130-inch aft, port, upward-opening door, strengthened floor, and freight loading system, facilitating several load combinations, including 268 passengers and seven pallets, 290 passengers and dix pallets, or up to 13 pallets. The type was first delivered to KLM on September 1, 1989.
Another variant was the 747-400D for “domestic.” Considered an advanced counterpart to the earlier 747SR for short, high-density Japanese sectors, it omitted the six-foot wing extensions and winglets, was powered by lower thrust engines, and offered a 600,000-pound maximum takeoff weight, although it was certifiable up to 870,000 pounds.
The first 747-400D, which was the 844th 747 airframe of all versions, first flew in March of 1991 and was delivered to Japan Air Lines in October. All-Nippon Airlines, another operator, configured the aircraft for 27 business and 542 economy class passengers.
The 747-400F, yet another version, replaced the 747-200F, whose production was discontinued after Air France placed a launch order for five on September 13, 1989. Devoid of passenger windows and facilities, and employing the standard-length upper deck of the 747-100, -200, and -SP, it featured both upward-opening nose and side cargo doors, a flight deck-reaching foldable ladder, and a two-person crew rest area. It could carry 26 more tons of cargo 1,200 miles further than its earlier -200F counterpart.
Volume totaled 27,467 cubic feet, including 21,347 on the main deck, 5,600 in the lower deck holds, and 520 in the bulk. Two ten-foot high pallets could also be accommodated on the upper deck.
The first 747-400F, the 968th 747 built, was first rolled out on February 25, 1993, and first took to the skies three months later, on May 4. The type’s maximum gross weight was 875,000 pounds. Because Air France had since canceled its order, Cargolux inaugurated the type into service instead.
The last version was the 747-400ER, intended, as its designation indicates, for “extended range” operations. Initially offered to Qantas as the 747-400IGW “increased gross weight,” it featured one or two 3,064-US gallon auxiliary tanks installed in the hold, increasing fuel capacity to 63,403 gallons and range to 7,500 nautical miles with one tank and 7,700 miles with two.
Powered by 63,300 thrust-pound PW4062 engines, the -400ER had a 535,000-pound zero-fuel weight, a 910,000-pound maximum takeoff weight, and a 652,000-pound landing weight. Design range with 416 passengers was 7,585 miles.
On September 10, 1993, the 1,000th 747, a -400 series for Singapore Airlines, was rolled out, making it the fifth Boeing type to achieve this production milestone after the 707, 727, 737, and (originally McDonnell-Douglas) MD-80. By January 1, 2002, 41 operators had ordered 630 747-400s of all versions. Production ultimately totaled 694.