Sciences - Other

Boeing 717 Aircraft MD 95 Aircraft History Mcdonnell Douglas Jetliners

Robert Waldvogel's image for:
"Boeing 717 Aircraft MD 95 Aircraft History Mcdonnell Douglas Jetliners"
Image by: 

Tracing its lineage to the DC-9, the MD-80, and the MD-90, the Boeing 717, which had inceptionally been designated the MD-95, had been the last purely-McDonnell-Douglas aircraft and the first and only to have been transferred to Boeing for continued production.

Conceived as an advanced, low-wing, 100-passenger airliner with two aft-mounted, high bypass ratio turbofans and a t-tail most closely based on the MD-90, its immediate predecessor, the design, intended for high-frequency, short- to medium-range routes, had nevertheless inherently incorporated the 40-year development history of its earlier-generation family. Having carried the three manufacturer names of Douglas, McDonnell-Douglas, and Boeing, the basic airframe had featured three wingspans; three powerplant cores...of the Pratt and Whitney JT8D, the International Aero Engine V2500, and the BMW Rolls Royce BR715; a vast range of thrust capabilities, from 12,000 to 25,000 pounds; four basic designations...of DC-9, MD-80, MD-90, and MD-95/717; passenger capacities varying between 90 and 180 in single-class arrangements; and eight fuselage lengths, as the DC-9-10, the DC-9-30, the DC-9-40, the DC-9-50, the MD-80, the MD-87, the MD-90, and the 717.

Intended as a next-generation DC-9-30 replacement, numerically the most popular DC-9 version with 662 having been sold, the originally-designated MD-95 features a 124-foot overall length, which is 1.7 feet shorter than that of the DC-9-40, permitting a 106-passenger complement in a four-abreast, two-two, first class cabin at a 36-inch seat pitch and a five-abreast, two-three, economy cabin at a 32-inch seat pitch. One hundred seventeen can alternatively be accommodated in a single-class, five-abreast configuration. Two underfloor holds facilitate baggage, cargo, and mail storage.

The state-of-the-art, two-person cockpit is equipped with six interchangeable liquid crystal display (LCD) units, an electronic instrument system (EIS), a dual flight management system (FMS), a control fault display system (CFDS), and an advanced Honeywell VIA 2000 computer, and is capable of category IIIA landings, with provision for lower-minimum IIIB operations.

Its all-metal, two-spar wing, like that of previous DC-9s, MD-80s, and MD-90s, features full-span, dual-position, five-section leading edge slats; two-section spoilers; three-section, double-slotted, trailing edge flaps; and manually-actuated, cable-connected ailerons differentially operated in flight for banking and roll control. The wings, with a 93.4-foot span, are sweptback 24 degrees for a maximum Mach 0.82 speed.

The t-tail, positioned well above the engines, eliminates engine thrust interference with its horizontal surfaces, whose elevators are cable-connected and manually operated, while the vertical stabilizer's rudder is hydraulically-deflected with fly-by-wire trimming. The MD-95/717's tail surfaces employ thicker skins than those of either the preceding MD-80 or MD-90.

Powered by two aft-mounted, BMW Rolls Royce BR715-A1-30 high bypass ratio turbofans, each rated at 18,500 pounds of thrust, the aircraft, completely free of engine installation on its wings, generates maximum wing lift for optimum performance. Based upon the single-core BR700, the BR715 features a two-stage, high-pressure turbine; a 58-inch fan chamber; single crystal turbine fan blades; the largest combined blade and disk (blisk) ever employed by a commercial powerplant; and is thrust-reverser equipped. The 19-foot-long, 6,155-pound engine, the third basic type to have powered the DC-9 family, had first run on April 28, 1997, almost attaining 26,000 pounds of thrust at this time. It is the MD-95's sole powerplant.

The aircraft sits on a dual-wheeled, hydraulically actuated tricycle undercarriage.

Launch order for the initially-designated MD-95-30, comprised of 50 firm orders and 50 options, had been placed on October 19, 1995 by ValuJet, a DC-9 and MD-80 operator, and the prototype, a former Eastern Airlines DC-9-30 modified to MD-95 standard and registered N717XA, had been rolled out three years later, on June 10, 1998, first taking to the skies on September 2. The aircraft, reflecting Boeing's prior-year acquisition of McDonnell-Douglas and its 7-dash-7 number scheme, had been redesignated "717," nomenclature shared by Boeing's own KC-135A Stratotanker, the military derivative of the 707.

The first production aircraft, registered N717XD, had first rolled out on January 23, 1999, and the type had received its joint FAA and JAA certification nine months later, on September 1, after a 2,000-hour flight test program entailing 1,900 individual sorties and five airframes.

The first aircraft, N942AT, had been delivered to newly branded AirTran Airways, hitherto a 737 operator, which ValuJet had intermittently acquired, on September 23, and had been inaugurated into service the following month on the Atlanta-Washington route.

The 717-200, the initial and only version, had been offered with both basic and high gross weight options. The former, at 110,000 pounds, features a 1,430-nautical mile range with a 24,609 US gallon fuel capacity, while the latter, at 121,000 pounds, features a 2,060-nautical mile range with a 29,500 US gallon fuel capacity, but reduces the underfloor space because of the additional tankage and requires the upgraded, 21,0000 thrust-pound BR715-C1-30 engine.

The aircraft's maximum certified altitude is 37,000 feet.

A triangular, tri-sector flight with AirTran Airways, from New York/La Guardia to Akron, Ohio; Atlanta, Georgia; and back to New York, is indicative of the mission for which the 717 had been designed.

Following a brigade of Canadair and Embraer "mini-jets," but mirrored by the long-fuselaged "big brother" American MD-82 and the identical, Atlanta-bound AirTran 717-200 immediately ahead of it, the 717, operating as Flight 202 and registered N926AT, crossed the arrivals runway, 4-22, before maneuvering on to the departure strip, Runway 13. Lightly loaded, with only some 20 passengers on board, the twin-engined, t-tailed aircraft lifted its main wheels off the concrete and trimmed itself into a steep, initial climb angle, tucking in its tricycle undercarriage in the 55-degree, spring-like air.

Surmounting the house geometries of Queens and closing the gap to the opaque, tracing paper-thin cloud film, Flight 202 banked left abreast of the Throgs Neck Bridge over the deep blue of Flushing Bay. Throttling back to climb power, it banked further left.

Manhattan Island, appearing beyond the left wing tip in miniature form and seeming to float between the Hudson and East Rivers, triumphantly projected its tall, needle-thin buildings to and through the low, ground-hovering mist like victorious bastions of man's architectural war. Beyond the Verrazano-Narrows Bridge, gateway to the Atlantic, the sun metamorphosed the water into a copper glass reflection.

Now assuming a shallow, barely perceptible ascent angle, the 717, the ultimate evolution of the DC-9, crossed the eastern fringes of the Allegheny Mountains, which appeared like black, charcoal-sketched waves 35,000 feet below.

Aided by the barely-raised, upper wing surface speed brake panels, the twin-engined aircraft initiated a shallow descent some 40 minutes later beneath dirty white and gray, January-indicative cloud strata toward the farm patterns of eastern Ohio, thudding through light chop.

The perpendicular runways of the Akron-Canton Airport moved into view ahead and to the left. Extending its leading edge slats, which produced significant drag, Flight 202 completed its undercarriage and trailing edge flap sequencing, arcing into a final, approach-course left bank. Skimming the bare, brown tree-bordered farm patches at drag-counteractive engine settings, the 717-200 flared beyond the runway's threshold and sideslipped into abrupt, crosswind contact.

Taxiing past the circular, brick Akron-Canton Terminal, into which four United Express, US Airways Express, and Delta Connection ERJ-135s and CRJ-200s had been nosed, the aircraft, the largest on the ramp, starved its aft-mounted engines of fuel, which spooled down into silence, replaced by the ringing of the jetbridge extending toward the forward, left passenger door.

Pushed back from the gate at 1215, the AirTran 717, now operating nonstop to Atlanta as Flight 202, initiated its unobstructed taxi at the Akron-Canton regional airport and received immediate take off clearance on Runway 19. Disengaging itself from the ground, the aircraft, with a considerable passenger complement, retracted its undercarriage with a light thud and climbed out over Ohio's patchwork quilt of farmland, which later yielded to soft hills. With altitude, these were altogether reduced to indistinguishable obscurity.

Emerging from white, encasing cloud over the green corrugated topography of West Virginia and Kentucky at 37,000 feet, the twin-engined, t-tailed jetliner paralleled the line of cottony nimbus which had tied itself together along the eastern seaboard.

The chocolate brown ridges of the Great Smoky Mountains of North Carolina crested like solid waves which had petrified at their peaks and had failed to descend back into the sea.

The upper wing surface speed brakes induced the 717 into a rapid descent over Georgia toward swollen, white cumulous snow banks, its bullet nose boring through the engulfing obscurity like a penetrative missile. Banking on its longitudinal axis, it initiated a series of arrival aircraft spacing s-turns, lurched by the cloud-associated air upset, while throttle-jockeying resulted in a series of periodic airspeed oscillations: as the airspeed peeled off, the engines were significantly spooled up, followed by a frequency of velocity deterioration, before the process had been repeated.

The aircraft emerged from the cloud islands over Georgia's green and brown ground blanket. The skyscrapers of Atlanta, although still in miniature form, loomed into view off the left wing.

Extending its tricycle undercarriage into the slipstream and increasing its wings' upper surface camber and area to their maximums with full, trailing edge flap travel, the 717 made a final left bank toward Runway 28 in the pure-blue, 68-degree skies dotted with suspended fluffs of cotton candy. Paralleled, on the left, by a Delta 757-200 and an ASA CRJ-100 approaching Runways 27-Left and Right, the t-tailed pure-jet crossed the threshold, spooling down its engines for a final time, which profiled it for a flare, and crouched onto the concrete with its main landing gear "hind legs," which absorbed the contact with minimal protest.

The return flight, operating nonstop, had occurred later than evening.

An onslaught of light pinpoints, representing final approaches to Atlanta's Hartsfield-Jackson International Airport on that dark January evening, seemed to vie, in competitive speed, for Runways 27-Left and Right, toward which the AirTran 717-200, operating as Flight 343 from Gate C-12 to New York-La Guardia, currently taxied. Turning on to the threshold of the right of the two parallel strips, it throttled into an engine-pinnacling acceleration roll and, seesawed into a nose-high angle by its horizontal stabilizers, generated sufficient lift to disengage itself from Georgia soil and plunge into engulfing, low-lying cloud.

Retracting its undercarriage, it shed itself of the obscurity. Thin, horizontal strata of mist rendered the orange ground lights an ethereal blur, a muted, only partially successful attempt to penetrate the veil from the "other side."

Separating itself from civilization, the twin-jet settled into its autonomous, 35,000-foot plateau, from which it could view, but not touch, the world, in miniature, below. Threading itself up the East Coast, it overflew Greenville/Spartanburg, South Carolina; Greensboro, North Carolina; and Richmond, Virginia, represented by their respective ground light splotches, "spills" of iridescent paint which had been tossed on to earth's black canvas without form or forethought.

Routed, according to its flight plan, east of Washington and Philadelphia, Flight 343, a self-contained, lighted world pursuing its invisible track in the January blackness, followed the coast of New Jersey.

Leading edge slat extensions, permitting airspeed to bleed off, occurred 40 miles from the airport. La Guardia approaches, to Runway 22, would take the aircraft to the north before it could turn final.

Momentarily caught in the black, referenceless void between Upper New York Bay and the late-night sky, the aircraft passed to the right of the tiny Statue of Liberty and the lighted, jewel-glittering sculptures of Manhattan Island, beyond which the perpendicular runway-patterned field of La Guardia rolled.

Following, in precision, the pattern of aircraft approach lights, the 717 banked left over the black reflective surface of Long Island Sound beyond the green light necklace-strung Throgs Neck and Whitestone Bridges.

Executing a long, final approach over the Connecticut coast at a 132-knot speed, the twin-jet unleashed its undercarriage, and extracted the last amount of lift obtainable from its swept-back wings with full trailing edge flap extensions, a contradictory maneuver which created as much drag as it did lift and could only be truly counteracted with increased engine power.

Bowing toward Flushing Bay with its nose, it passed over the pier supporting Runway 22's threshold and flared into the headwind, re-snatching concrete with its main wheels and unleashing its spoilers and thrust reversers in a simultaneous explosion. An American 737-800, which had preceded its landing, had just turned on to the parallel taxiway.

On May 23, 2006, during a ceremony attended by thousands, Boeing had rolled out the last two 717s ordered by Midwest and AirTran Airways, marking the final deliveries of the design, the final McDonnell-Douglas commercial aircraft, and the closure of its historic Long Beach production facility.

Founded by Donald W. Douglas, the Douglas Aircraft Company had flown its first airplane, the "Cloudster," in 1921, and had opened its Long Beach facilities in 1941, on the eve of World War II, when demand had eclipsed capacity at its existing Santa Monica and El Segundo, California, plants. The first Douglas Commercial design, the DC-1, had been constructed here and sold to Transcontinental and Western Air (TWA), becoming the forerunner of a long line of increasingly advanced piston airliners which had introduced the world to commercial flight.

Merging with the McDonnell Company in 1967, the Douglas Aircraft Company had been renamed McDonnell-Douglas, its products comprising the new corporation's commercial division, and, 30 years later, when Boeing had acquired McDonnell-Douglas, it had become the Douglas Products Division. Ultimately, it had been designated the Long Beach Division of Boeing Commercial Airplanes.

During its more than 65-year history, the Long Beach factory had produced some 10,000 military aircraft during World War II and 15,000 airplanes of both military and commercial design overall, while more than 65,000 airframes had been produced by all of its locations.

Despite more efficient, cost-effective final assembly techniques devised by Boeing, the 717 had been unable to remain competitive, partly due to sales conflicts with its own 737-600. Nevertheless, the 156 717s produced, along with the 976 earlier-generation DC-9s, 1,191 MD-80s, and 114 MD-90s, had already provided almost half a century of rugged, reliable, and economical service throughout the world, and seemed likely to do so for many years to come.

More about this author: Robert Waldvogel

From Around the Web