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McDonnell Douglas DC-10

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The McDonnell Douglas DC-10 is a three-engined medium to long-range widebody 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 Lockheed L-1011 TriStar, which appears similar to the DC-10.

Production of the DC-10 ended in 1989 with 386 delivered to airlines and 60 to the U.S. Air Force as air-to-air refueling tankers, designated the KC-10 Extender.[1] The DC-10 was succeeded by the related McDonnell Douglas MD-11 which entered service in 1990.

History

The design of the DC-10 began in 1967.[2] It became McDonnell Douglas's first commercial airliner after the merger between McDonnell Aircraft Corporation and Douglas Aircraft Company in 1967. 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 it because of gate restrictions and runway length. McDonnell Douglas was able to capitalize on this with the DC-10. In particular, the DC-10's trijet design met requirements for NYC's LaGuardia Airport, flying over the Rockies, and flying not transoceanically but at least throughout the Caribbean.

The DC-10 first flew on August 29 1970 and entered commercial service in 1971, nearly a year before the Lockheed L-1011 TriStar (which was built to a similar specification). The launch customers for the DC-10 were United and American Airlines. Both were Series 10s.

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 (mostly ordered by Northwest Orient and Japan Airlines) had a typical load range of 5750 statute miles (9,265 km) or a maximum payload range of 7,520 km. The series 40 was powered by Pratt & Whitney engines, whereas the series 10 and 30 engines were from General Electric. One of the main visible differences between the models is that the series 10 has three sets of landing gear (one front and two main) while the series 30 and 40 have four (3 mains), as an extra 2-wheel main landing gear (which extends from the center of the fuselage) was added to compensate for the extra weight.

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. Outward opening doors allowed larger openings required by baggage for a wide-body 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 explosive decompression. Following the Turkish Airlines Flight 981 crash in 1974, the cargo door on all DC-10s underwent a mandatory redesign.

Other initial design problems included its lack of locking flap mechanisms designed to maintain their position in the event of a hydraulic or pneumatic failure. The lines from all three independent and redundant hydraulic systems were located in close proximity, directly beneath the tail engine. The MD-11, and the DC-10 now incorporate hydraulic fuses to prevent such catastrophic loss of control in event of a hydraulic failure.

Despite its troubled beginnings, the DC-10 ultimately proved a reliable aircraft, much loved by engineers and pilots. The original DC-10-10's notorious 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.[3] Increased inspections and modifications made the DC-10 among the safest aircraft for passenger travel. Nonetheless, because of its poor record in the 1970s, the DC-10 acquired an unfavorable reputation.[4]

The 446th and final DC-10 rolled off the production line in December 1988 and was delivered to Nigeria Airways in July 1989. The DC-10 was assembled at McDonnell Douglas's Douglas Products Division in Long Beach, California.

Variants

The DC-10 was manufactured in a number of different variants:

  • DC-10-10 {122 built): 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.
File:McDonnell Douglas KC-10 Extender.jpg
KC-10 Extender during refueling
  • DC-10-10CF (9 built): Convertible passenger/cargo transport aircraft.
  • DC-10-15 (7 built}: Also known as the "DC-10 Sport", designed for use at hot high-altitude airports. The series 15 was fitted with higher-thrust GE CF6-50 powerplants. Only built for Mexican carriers Aeroméxico and Mexicana. Produced from 1979 with 7 built.
  • DC-10-20 : Proposed but unbuilt DC-10-10 powered by Pratt & Whitney JT9D turbofans. With minimal airline interest for the original -20, the name was initially recycled to cover the Pratt-powered version of the intercontinental-range DC-10-30. Northwest, one of the launch customers for this longer-range JT9D-powered DC-10 requested the name change to -40 (see -40 entry below).
  • DC-10-30 (164 built): The most common model, built with General Electric CF6-50 turbofan engines and larger fuel tanks to increase range and fuel efficiency, as well as a set of rear center landing gear to support the increased weight. It was the second long-range model after the -40 and very popular with European flag carriers. Produced from 1972 with 164 built.
  • DC-10-30CF (26 built): Convertible cargo/passenger transport version.
  • DC-10-30ER (6 built): Extended range version.
  • DC-10-30F (10 built): All freight version.
10 Tanker during a water drop demonstration
  • DC-10-40 (42 built): 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. Northwest and JAL were the only airlines to order the series 40. Produced from 1972 with 42 built.
  • KC-10A Extender (60 built): Military version of the DC-10-30 used for aerial refueling. The aircraft was ordered by the U.S. Air Force. Produced from 1981. It is the longest-ranged production aircraft in the world.
  • KDC-10 (2 built): Aerial refuelling tanker for the Royal Netherlands Air Force. Converted from civil airliners (DC-10-30CF) to a similar standard as the KC-10.
  • MD-10: This was retrofit cockpit upgrade to the DC-10 and a re-designation to MD-10. The upgrade included a Advanced Common Flightdeck (ACF) used on the MD-11.[5] The new cockpit eliminated the need for the flight engineer position and allowed common type rating with the MD-11. 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.
  • 10 Tanker: A DC-10-10 converted into a firefighting tanker aircraft.

Incidents and accidents

The early DC-10s suffered a trying time during the 1970s when a string of notorious incidents and crashes led to a brief grounding by the United States Federal Aviation Administration.

The outward opening cargo door design problem was first identified in 1972, when American Airlines Flight 96 lost its aft cargo door after takeoff from Detroit, but the crew were able to perform an emergency landing with no further incident. Before Flight 96 took off, an airport employee had 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, and two years after the American Airlines incident, an almost identical cargo door blow-out caused Turkish Airlines Flight 981 to crash 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 accident; 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. Vents were not present to allow the pressure between the cargo and passenger compartments to equalize. 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.

Northwest Airlines DC-10-30

In 1979, with the cargo door issues resolved, DC-10s (all series) 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. As the engine separated upwards, it ripped through the leading edge of the wing, rupturing hydraulic lines which caused the port wing slats to retract. As speed was reduced in the climbout, the left wing stalled, the plane rolled left and crashed before the flight crew could recover.

The United States National Transportation Safety Board (NTSB) 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.

The Chicago incident also highlighted a major deficiency in the DC-10 design—its lack of locking flap mechanisms designed to maintain their position in the event of a hydraulic or pneumatic failure. Other widebody aircraft of the day carried such a feature, but it was omitted from the DC-10. Another deficiency highlighted in the NTSB report was the vulnerable placement of electrical wiring at the leading edge (front) of the wing. When the engine pulled up and over the wing, it tore out these electrical wires, thus rendering inoperable vital warning instruments in the cockpit. Other aircraft of this era typically placed this kind of wiring in the center of the wing, in a less vulnerable position.

In 1979, an Air New Zealand DC-10-30 flew into Mount Erebus in Antarctica during a sight-seeing trip. All 257 on board Air New Zealand Flight 901 were killed. The accident was caused by complex factors not related to the airworthiness of the aircraft.

The Sioux City Flight 232 DC-10 crash

Perhaps the most infamous instance of a DC-10 crash was the Flight 232 disaster at Sioux City, Iowa, USA, in 1989. After the #2 engine (tail engine) suffered an uncontained fan disk failure in flight which ruptured critical hydraulic lines, the crew, led by Captain Al Haynes and assisted by a senior pilot flying as a passenger (Dennis E. "Denny" Fitch), performed an emergency landing by varying remaining engine power to control the plane. Although the aircraft was destroyed with the loss of many lives, the crew flew the aircraft onto the runway in a partially controlled manner and 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 fan disk separation failure penetrated all three lines resulting in total loss of control to the elevators, ailerons and rudder.

The Air France Concorde crash of 2000 was attributed to a fragment of titanium metal that fell from a Continental Airlines DC-10 that had taken off some four minutes earlier.

Operators

Current operators

DC-10-30 with landing gear extended.

The aging model is now largely being used as a dedicated freight aircraft. Many mainline carriers have sold their aging DC-10 fleets to cargo carriers such as FedEx. Some aircraft have been modernized to MD-10s by adding a glass cockpit, which eliminates the need for a flight engineer. Other DC-10 aircraft continue in charter service with their three-person flight deck configurations.

Some passenger airlines, such as Omni Air International, continue to operate the DC-10 on trunk routes. The Royal Netherlands Air Force has converted the aircraft to KDC-10 flying tankers. The Orbis International use a DC-10 as flying eye hospital.

On January 8, 2007 Northwest Airlines stopped international service with the DC-10.[6] Regarding the retirement of Northwest's DC-10 fleet, Wade Blaufuss, spokesman for the Northwest chapter of the Air Line Pilots Association says, "The DC-10 is a reliable airplane, fun to fly, roomy and quiet, kind of like flying an old Cadillac Fleetwood. We're sad to see an old friend go."[7] "The DC-10 is going to be remembered as a better cargo plane than passenger plane," says Richard Aboulafia, an analyst at the Teal Group.[7] In November 2006, ATA Airlines announced they had purchased seven of Northwest's remaining DC-10s, to replace ATA's aging L-1011 airplanes.

In August 2006, a total of 174 DC-10 aircraft (all versions) remain in service. Major operators include: FedEx Express (89). Some 29 other airlines also operate smaller numbers of the type.[8] Almost all DC-10s remaining in passenger service are series 30 aircraft.

Previous operators


Specifications

DC-10-10 DC-10-15 DC-10-30 DC-10-40
Cockpit Crew Three
Passengers 250-380 250-380 250-380 250-380
Length 182 ft 3 in (55.5 m) 180 ft 8 in (55 m) 181 ft 7 in (55.4 m) 182 ft 3 in (55.5 m)
Height 58 ft 1 in (17.7 m)
Wingspan 155 ft 4 in (47.3 m) 165 ft 4 in (50.4 m)
Operating empty weight 240,171 lb (108,940 kg) 266,191 lb (120,742 kg) 270,213 lb (122,567 kg)
Maximum take-off weight 430,000 lb (195,045 kg) 455,000 lb (206,385 kg) 572,000 lb (259,459 kg) 555,000 lb (251,701 kg)
Cruising speed 600+ mph (965+ km/h)
Max Range loaded 3,800 miles (6,112 km) 4,350 miles (7,010 km) 6,220 miles (10,010 km) 5,750 miles (9,265 km)
Maxximum fuel capacity 21,700 US gal
(82,134 L)		 26,647 US gal
(100,859 L)		 36,650 US gal
(138,720 L)		 36,650 US gal
(138,720 L)
Service ceiling 42,000 ft (12,802 m)
Engine model (x 3) GE CF6-6D GE CF6-50C2F GE CF6-50C PW JT9D-59A
Engine thrust (x 3) 40,000 lbf (177.9 kN) 46,500 lbf (206.8 kN) 51,000 lbf (226.9 kN) 53,000 lbf (235.8 kN)
Sources:[1], [2] and [3]

References

  1. ^ History - McDonnell Douglas DC-10 on Boeing.com (Accessed Feb. 28, 2006)
  2. ^ "DC-10 History on dc-10.net"
  3. ^ "Statistical Summary of Commercial Jet Airplane Accidents (1959-2005)".
  4. ^ "I will survive"
  5. ^ McDonnell Douglas and Federal Express to Launch MD-10 Program
  6. ^ Northwest retires its DC-10 fleet, January 8, 2007.
  7. ^ a b "Northwest to Retire Its Last DC-10".
  8. ^ Flight International, 3-9 October 2006

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