McDonnell Douglas DC-10

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Image:Ghana.airways.1.arp.750pix.jpg The McDonnell Douglas DC-10 is a three-engined medium to long-range airliner, with two engines mounted on underwing pylons and a third engine at the base of the vertical stabilizer. The model was a successor to the company's DC-8 for long-range operations, and competed in the same markets as the Airbus A300, Boeing 747 "jumbo jet", and the physically similar Lockheed L-1011 TriStar. 386 DC-10s were delivered to airlines and 60 were built for the U.S. Air Force as air-to-air refueling tankers, designated the KC-10 Extender. Template:Ref The DC-10 was succeeded by the related McDonnell Douglas MD-11 which entered service in 1990.

1 History
- 1.1 Safety record
2 Variants
3 Operators
4 Specifications
- 4.1 Specifications (DC-10-30)
  - 4.1.1 General characteristics
  - 4.1.2 Performance
5 References
6 External links
7 Related content

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History

The DC-10 was McDonnell Douglas's first commercial airliner, after the 1967 merger between McDonnell Aircraft Corporation and Douglas Aircraft Company. It was built to a specification from American Airlines for a widebody aircraft smaller than the Boeing 747 but capable of flying similar long-range routes from airports with shorter runways. In some ways, the Boeing 747 was ahead of its time as several smaller airports could not accommodate because of gate restrictions and runway length. McDonnell Douglas was able to captialise on this with the DC-10.

The DC-10-10 first flew on August 29 1970 and entered commercial service in 1971, nearly a year before the Lockheed Tristar (which was built to a similar specification). The launch customers for the DC-10-10 were United and American Airlines.

The first DC-10 version was the "domestic" series 10 with a range of 3800 statute miles (6,112 km). The series 30 had a typical load range of 6,220 statute miles (10,010 km) or a maximum payload range of 7,410 km. The series 40 had a typical load range of 5750 statute miles (9,265 km) or a maximum payload range of 7,520 km. One of the main visible differences is that the series 10 has three sets of landing gear while the series 30 and 40 have four. The extra 2-wheel main landing gear was added to the series 30 and 40 to compensate for the extra weight.

The 446th and final DC-10 rolled off the production line in December 1988 and was delivered to Nigeria Airways in early 1989.

Despite its troubled beginning, the DC-10 ultimately proved — and continues to be — a reliable aircraft, much loved by engineers and pilots. The aircraft's safety record continually improved as design flaws were ironed out and fleet hours increased. In fact, the DC-10's lifetime safety record as of 2003 is comparable to similar second generation passenger jets. Template:Ref Increased inspections and modifications have made the DC-10 one of the safest aircraft to travel on.

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Safety record

Although the DC-10's lifetime safety record is comparable to that of other heavy passenger jet aircraft, the DC-10 suffered a trying time during the 1970s when a string of highly publicized incidents and crashes snowballed into a brief grounding by the United States Federal Aviation Administration. The result of this grounding, however, was a more efficient and safer DC-10.

The DC-10 was designed with cargo doors that opened outward instead of inward, as inward opening "plug-type" doors used on smaller pressurized aircraft are not well-suited to the larger openings into the cargo hold necessitated by the increased baggage load of a jumbo jet. Outward opening doors rely on a heavy locking mechanism to secure the door against the outward force caused by the pressurization of the fuselage. In the event that the door lock malfunctioned, there was potential for catastrophic blow-out of the whole door. This sort of depressurization caused a failure of the rear floor of the passenger cabin because vents were not present to rapidly equalize the pressure between the cargo and passenger compartments. Cables running from the flight deck to the rear control surfaces are embedded in the floor frame and a collapse would lead to a compromise of the flight deck's ability to control the plane.

This problem was first identified in 1972, when American Airlines Flight 96 lost its aft cargo door after takeoff from Detroit, but fortunately the crew were able to perform an emergency landing with no further incident. Before Flight 96 took off, an airport employee had violently forced the door shut, weakening the locking pin and causing the door to subsequently blow-out as the plane reached altitude. McDonnell Douglas attempted to place the blame on the employee, whom they described as "illiterate", and deflected criticism of the aircraft design itself.

Although many carriers voluntarily modified the cargo doors and re-trained their ground crews, there was not yet a mandatory redesign of the system. Severe design problems still persisted with the aircraft's cargo doors, however. Two years after the American Airlines incident, an almost identical cargo door blow-out befell Turkish Airlines Flight 981, which crashed into a forest shortly after leaving Orly Airport in Paris on March 3, 1974. 346 people were killed in one of the worst aviation disasters of the twentieth century. The circumstances surrounding this crash were similar to those surrounding the previous crash; however, a modified seating configuration on the Turkish aircraft exacerbated the effects of decompression which caused the floor of the aircraft to collapse into the cargo bay. Control cables running through the floor of the plane were severed when the floor collapsed and this rendered the aircraft uncontrollable. In the aftermath of this crash, all DC-10s underwent a mandatory door redesign. The DC-10 was starting to get a reputation as a dangerous aircraft.

Image:Northwest.arp.750pix.jpg In 1979, with the cargo door issues resolved, DC-10s around the world were grounded following the crash of American Airlines Flight 191, which killed 273 people. Flight 191 lost its number one wing engine after taking off from O'Hare International Airport in Chicago, USA, May 25 1979. The engine loss damaged the aircraft's lift enhancement system on that wing and also damaged warning systems, causing it to lose control. As the engine separated upwards, it ripped through the leading edge of the wing, rupturing pneumatic lines causing the port wing slats to retract. Losing lift on one side, the plane rolled left and crashed before the flight crew could recover.

The United States National Transportation Safety Board officials discovered that a maintenance procedure was the culprit: American Airlines mechanics had removed the engine and its pylon at the same time (rather than removing the engine from the pylon then the pylon from the wing, as recommended by McDonnell Douglas), using a forklift, and the forklift operator had inadvertently cracked the pylon in the process. The short-cut procedure, thought to save several man hours on maintenance, was not approved by McDonnell Douglas, but most major airlines used it. Although McDonnell Douglas was not at fault for the pylon separation, it redesigned the DC-10 to allow more redundancies in the hydraulic systems. (It is rumored, although not confirmed, that the crash was a factor in a deal several years later where AA purchased a large order of McDonnell Douglas MD-80's at a discount.)

The Chicago incident also highlighted a design deficiency in the DC-10 design, due to its lack of locking flap mechanisms that are designed to maintain their position in the event of a hydraulic failure. Other widebody aircraft of the day carried such a feature, but it was omitted from DC-10.

In 1979, an Air New Zealand DC-10-30 flew into Mount Erebus in Antarctica during a sight-seeing trip. The Mount Erebus disaster killed all 257 on board. The accident was caused by complex factors, not limited to pilot error, and not related to the airworthiness of the aircraft.

Perhaps the most infamous instance of a DC-10 crash was the Flight 232 disaster at Sioux City, USA, in 1989. After the #2 engine suffered an uncontained fan disk failure in flight, the crew performed an emergency landing by varying remaining engine power as they had no hydraulic power to the controls. Although the aircraft was completely destroyed and with the loss of many souls, over half of the passengers survived.

The Sioux City crash concerned investigators because the total loss of hydraulic pressure aboard the DC-10 was considered nearly impossible. The design, however, had lines from all three independent and redundant hydraulic systems in close proximity, directly beneath the #2 (tail) engine. Debris from the #2 disk failure penetrated all three lines.

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Variants

The DC-10 was manufactured in five different variants:

DC-10-10 : Original version, produced from 1970. The main customers for this domestic version were American Airlines and United Airlines. The DC-10-10 was equipped with GE CF6-6 engines, which was the first civil engine from the successful CF6-family.
DC-10-10F : Convertible passenger/cargo transport aircraft.
DC-10-15 : Also known as the "DC-10 Sport", designed for use at hot high-altitude airports. The series 15 was fitted with higher-thrust General Electric CF6-50 powerplants. Only 7 were built for Mexican carriers Aeroméxico and Mexicana. Produced from 1979.
DC-10-30 : The most common model, built with General Electric CF6-50 turbofan engines and larger fuel tanks to increase range and fuel efficiency. It was the second long-range model after the DC-10-40 and very popular with European flag carriers. Produced from 1972.
DC-10-30CF : Convertible cargo/passenger transport version.
DC-10-30ER : Extended range version.
DC-10-30F : All freight version.
DC-10-40 : First long-range version, fitted with Pratt & Whitney JT9D engines. Originally designated DC-10-20, this model was renamed DC-10-40 after a special request from Northwest Airlines for marketing purposes. Northwest felt that customers perceived the -40 series designation to be more advanced. This US-carrier and JAL were the only airlines to order the series 40. Produced from 1972.

Image:McDonnell Douglas KC-10 Extender.jpg

KC-10 Extender: Military version of the DC-10-30 used for aerial refueling. The aircraft was ordered by the US Air Force. Produced from 1981. It is the longest-ranged production aircraft in the world.
KDC-10 : Aerial refuelling tanker for the Royal Netherlands Air Force. Converted from civil airliners to a similar standard to the KC-10.

McDonnell Douglas later produced a larger variant called the MD-11. The MD-11 used newer engines, plus a glass cockpit, which eliminated the need for the flight engineer position. The MD-11 entered service in 1991. In addition, some DC-10s have been upgraded by Boeing to the so-called MD-10. The MD-10 has an upgraded cockpit giving it certain benefits of the more modern MD-11 cockpit, and more importantly, a common type rating. This allows companies such as Federal Express, which operate both the MD-10 and MD-11, to have a common pilot pool for both aircraft.

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Operators

The aging model is now finding a new lease on life as a dedicated freight aircraft: many mainline carriers have sold their obsolete DC-10 fleets to cargo carriers such as FedEx. Some passenger airlines, most notably Northwest Airlines, and Omni Air International, continue to operate the DC-10 on trunk routes (although NWA has plans to phase out their DC-10s in the near future). Almost all DC-10s remaining in passenger service are series 30 aircraft. The aircraft is also getting a new lease of life through the Royal Netherlands Air Force and their KDC-10 flying tanker conversions.

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