McDonnell Douglas MD-80

The McDonnell Douglas MD-80 series are twin-engine, medium-range, single-aisle commercial jet airliners. The MD-80 aircraft were lengthened and updated from the DC-9. The MD-80 series can seat from 130 up to 172 passengers depending on variant and seating arrangement.

The MD-80 series was introduced into commercial service on October 10, 1980 by Swissair. The MD-80 series was followed into service in modified form by the MD-90 in 1995 and the MD-95/Boeing 717 in 1999.

Design and development
Background

Douglas Aircraft developed the DC-9 in the 1960s as a short-range companion to their larger DC-8.^[1] The DC-9 was an all-new design, using two rear fuselage-mounted turbofan engines, and a T-tail. The DC-9 has a narrow-body fuselage design with 5-abreast seating, and holds 80 to 135 passengers depending on seating arrangement and aircraft version.

The MD-80 series was the second generation of the DC-9. It was originally called the DC-9-80 series and the DC-9 Super 80^[2] and entered service in 1980. The MD-80 series was then developed into the MD-90 entering service in 1995. The last variant of the family was the MD-95, which was renamed the Boeing 717-200 after McDonnell Douglas’s merger with Boeing in 1997.

The DC-9 family is one of the most successful jet airliners with a total of over 2,400 units produced; it ranks third behind the second place Airbus A320 family with over 4,000 produced, and the first place Boeing 737 with over 6,000 produced.

MD-80 series

The MD-80 series is a mid-size, medium-range airliner that was introduced in 1980. The design was the second generation of the DC-9 with two rear fuselage-mounted turbofan engines, small, highly efficient wings, and a T-tail. The aircraft has distinctive 5-abreast seating in coach class. It was a lengthened DC-9-50 with a higher maximum take-off weight (MTOW) and a higher fuel capacity. The aircraft series was designed for frequent, short-haul flights for 130 to 172 passengers depending on plane version and seating arrangement.

SAS MD-81 taking off

The development of MD-80 series began in the 1970s as a growth version of the DC-9 Series 50. Availability of new Pratt & Whitney JT8D higher bypass engines drove early studies including designs known as Series 55, Series 50 (Re-fanned Super Stretch), and Series 60. The design effort focused on the Series 55 in August 1977. With the projected entry into service in 1980, the design was marketed as the “DC-9 Series 80″. Swissair launched the Series 80 in October 1977 with an order for 15 plus an option for five.^[1]

The Series 80 featured a fuselage 14 feet 3 in (4.34 m) longer than the DC-9-50. The DC-9 wings were redesigned by adding sections at the wing root and tip for a 28% larger wing. The initial Series 80 first flew October 19, 1979.^[1]

It entered service in 1980. Originally it was certified as a version of the DC-9, but was changed to MD-80 in July 1983, as a marketing move. New versions of the series were initially the MD-81/82/83 and the shortened MD-87, even though their formal certification was DC-9-81/82 etc. Only the MD-88 was given an “MD” certification, as was the later MD-90.

Spanish airline Spanair MD-83 at Leeds Bradford Airport, UK

The MD-80 versions have cockpit, avionics and aerodynamic upgrades along with the more powerful, more efficient and quieter JT8D-200 series engines, which are a significant upgrade over the smaller JT8D-15, -17, -11, and -9 series. The MD-80 series aircraft also have longer fuselages than their earlier DC-9 counterparts, as well as longer range. The MD-80′s production ended in 1999. Some customers, such as American Airlines, still refer to the planes in fleet documentation as “Super 80″. This model is still flown extensively by American Airlines and Delta Air Lines. Comparable airliners to the MD-80 series include the Boeing 737 and Airbus A320.

Flight testing and certification

The first MD-80, DC-9 line number 909, made its first flight on October 19, 1979. Test flying, despite two aircraft being substantially damaged in accidents, was completed on August 25, 1980, when the first variant of MD-80, the JT8D-209-powered MD-81 (or DC-9-81), was certificated under an amendment to the FAA Type Certificate for the DC-9. The flight testing leading up to certification had involved three aircraft accumulating a total of 1085 flying hours on 795 flights. The first delivery, to launch customer Swissair took place on September 13, 1980.^[3]

Model designation

As the MD-80 was not in effect a new aircraft, it continues to be operated under an amendment to the original DC-9 FAA aircraft Type Certificate (a similar case to the later MD-90 and Boeing 717 aircraft). The Type Certificate issued to the aircraft manufacturer carries the aircraft model designations exactly as it appears on the manufacturer’s application, including use of hyphens or decimal points, and should match what is stamped on the aircraft’s data or nameplate. What the manufacturer chooses to call an aircraft for marketing or promotional purposes is irrelevant to the airworthiness authorities. The first amendment to the DC-9 type certificate for the new MD-80 aircraft was applied as DC-9-81 which approved on August 26, 1980. All MD-80 models have since been approved under additional amendments to the DC-9 Type Certificate. In 1983, McDonnell Douglas decided that the DC-9-80 (Super 80) would be designated the MD-80. However, instead of merely using the MD- prefix as a marketing symbol, an application was made to again amend the Type Certificate to include the MD-81, MD-82, and MD-83. This change was dated March 10, 1986, and the Type Certificate declared that although the MD designator could be used in parentheses, it must be accompanied by the official designation, for example: DC-9-81 (MD-81). All Long Beach aircraft in the MD-80 series thereafter had MD-81, MD-82, or MD-83 stamped on the aircraft nameplate. Although not certified until October 21, 1987, McDonnell Douglas had already applied for models DC-9-87 and DC-9-87F on February 14, 1985. Third derivative was similarly officially designated DC-9-87 (MD-87), although no nameplates were stamped DC-9-87. For the MD-88, an application for a Type Certificate model amendment was made after the earlier changes, so there never was a DC-9-88, only the MD-88, which was certificated on December 8, 1987.^[4]

MD-80 production

The MD-80 was produced on a common line with the DC-9 with which it shares its line number sequence. However after the delivery of 976 DC-9s and 108 MD-80s, McDonnell Douglas stopped DC-9 production. Hence, commencing with the 1,085th DC-9/MD-80 delivery, an MD-82 for VIASA in December 1982, all DC-9s produced have been Series 80s/MD-80s.

As well as the Long Beach line, a second assembly line was set up at Shanghai, where aircraft were to be built under license.

During 1991, MD-80 production had reached a peak of 12 per month, having been running at approximately 10 per month since 1987 and was expected to continue at this rate in the near term (140 MD-80s were delivered in 1991). As a result of the decline in the air traffic and a slow market response to the MD-90, MD-80 production has been reduced, and 84 aircraft were handed over in 1992. A further production rate cut saw 42 MD-80s delivered during 1993 (3.5 per month) and 22 aircraft were handed over.^[3]

Derivative designs

The MD-90 was developed from the MD-80 series and is a 5-foot-longer (1.5 m), updated version of the MD-88 with a similar electronic flight instrument system (EFIS) (glass cockpit), and improved, and quieter IAE V2500 turbofan engines. The MD-90 program was begun in 1989, first flown in 1993, and entered commercial service in 1995.

A number of other variants were proposed that never entered production. One proposal was the MD-94X which was fitted with unducted fan turbofan engines. Previously, an MD-81 was used as a testbed for unducted fan engines, such as the General Electric GE36 and the Pratt & Whitney/Allison 578-DX.^[5]

The MD-95 was developed to replace early DC-9 models, then approaching 30 years old. The project completely overhauled the original DC-9 into a modern airliner. It is slightly longer than the DC-9-30 and is powered by new Rolls-Royce BR715 engines. The MD-95 was renamed Boeing 717 after the McDonnell Douglas—Boeing merger in 1997.

Operational history

A Delta MD-88 at Will Rogers World Airport in Oklahoma City, Oklahoma, USA

The MD-80 series has been used by airlines around the world. Major customers have included Aeroméxico, Alaska Airlines, Alitalia, Allegiant Air, American Airlines, Austral Líneas Aéreas, Austrian Airlines, Avianca, China Eastern Airlines, China Northern Airlines, Delta Air Lines, Finnair, Iberia, Japan Air System (JAS), Korean Air, Lion Air, Reno Air, Scandinavian Airlines System (SAS), Spanair, Dutch Caribbean Airlines, and Swissair.^[6]

Due to the usage of the aging JT8D engine, the MD-80 is not fuel efficient compared to the A320 or newer 737 models; it burns 1,050 gallons of jet fuel per hour on a typical flight, while the larger Boeing 737-800 burns only 850 gallons per hour (19% reduction). Many airlines have started to retire the type in the 2000s. Alaska Airlines’ tipping point in using the 737-800 was the $4 per gallon price of jet fuel the airline was paying by the summer of 2008; the airline stated that a typical Los Angeles-Seattle flight would cost $2,000 less, using a Boeing 737-800, than the same flight using an MD-80. American Airlines has announced plans to retire at least 20 MD-80s,^[7] and has accelerated delivery of new 737-800s,^[8] while Midwest Airlines announced on July 14, 2008, that it would retire all 12 of its MD-80s (used primarily on routes to the west coast) by the fall.^[9]^[10] The JT8D’s comparatively lower maintenance costs due to simpler design help narrow the fuel cost gap.

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