|DC-10 / MD-10|
|A DC-10-30 of Continental Airlines|
|Role||Wide-body jet airliner|
|National origin||United States|
|First flight||August 29, 1970|
|Introduction||August 5, 1971 with American Airlines|
|Status||In cargo service|
|Primary users||FedEx Express|
US$20M (1972) ($122M today)
|Developed into||McDonnell Douglas MD-11|
The McDonnell Douglas DC-10 is an American three-engine wide-body jet airliner manufactured by McDonnell Douglas. It has two turbofan engines mounted on underwing pylons and a third engine at the base of the vertical stabilizer. The DC-10 was intended as a successor to the company's DC-8 for medium- to long range flights, using a larger capacity wide-body layout with seating up to 380 and more powerful engines. Lockheed also saw this niche as an ideal place to reenter the commercial airliner market with their very similar L-1011 TriStar. Although the L-1011 was more technologically advanced, the DC-10 would go on to outsell the L-1011 by a significant margin due to the DC-10's lower price and earlier entry into the market.
The initial DC-10-10 model was a "domestic" design with a typical range on the order of 3,800 miles (6,100 km) in a two-class layout. The -15 was a version with more powerful engines, for hotter or higher-altitude airports. The -30 and -40 models were the "international" versions with extended range of up to 6,220 miles (10,010 km) and a third main landing gear leg to support the higher takeoff weights. An even longer-range version proposed for British Airways, the -50, was not built. The KC-10 Extender air-to-air refueling tanker version, was based on the -30 model. Production of the DC-10 ended in 1989, with 386 DC-10s delivered to airlines and 60 KC-10s to the U.S. Air Force.
The DC-10 had a poor safety record in early operations, especially due to a design flaw in the cargo doors. Its safety reputation was further damaged by the crash of American Airlines Flight 191, which remains the deadliest aviation accident in the United States. Following the Chicago crash, the FAA withdrew the DC-10's type certificate in June 1979, which temporarily grounded all U.S. DC-10s. In August 1983, McDonnell Douglas announced that it would end production of the DC-10, citing a lack of orders. Airline industry consensus at the time was that the DC-10 had a poor reputation for fuel economy and for its overall safety. In spite of the DC-10's early difficulties, it ultimately accumulated a good safety record, as design flaws were rectified and fleet hours increased, comparable to similar second-generation passenger jets as of 2008.
The DC-10 was succeeded by the McDonnell Douglas MD-11, essentially a lengthened version of the DC-10 with some design changes and greater range. Boeing, which merged with McDonnell Douglas in 1997, conducted an upgrade program that equipped many in-service DC-10s with a glass cockpit that eliminated the flight engineer position; the upgraded aircraft were re-designated as MD-10s. The DC-10's last commercial passenger flight took place in February 2014, although freighter versions continue to operate. The largest operator of the DC-10 is U.S. cargo airline FedEx Express. Despite the airliner's popularity, only a few DC-10s are on display, while other retired aircraft are in storage. DC-10s are also used for specialist services, such as the Orbis International Flying Eye Hospital, which has a compartment for performing eye surgery.
Following an unsuccessful proposal for the U.S. Air Force's CX-HLS (Heavy Logistics System) in 1965, Douglas Aircraft began design studies based on its CX-HLS design. In 1966, American Airlines offered a specification to manufacturers for a widebody aircraft smaller than the Boeing 747 but capable of flying similar long-range routes from airports with shorter runways. The DC-10 became McDonnell Douglas's first commercial airliner after the merger between McDonnell Aircraft Corporation and Douglas Aircraft Company in 1967. An early DC-10 design proposal was for a four-engine double-deck wide-body jet airliner with a maximum seating capacity of 550 passengers similar in length of a DC-8. The proposal was shelved in favor of a trijet single-deck wide-body airliner with a maximum seating capacity of 399 passengers, and similar in length to the DC-8 Super 60.
On February 19, 1968, in what was supposed to be a knockout blow to the competing Lockheed L-1011, George A. Spater, President of American Airlines, and James S. McDonnell of McDonnell Douglas announced American Airlines' intention to acquire the DC-10. This was a shock to Lockheed and there was general agreement within the U.S. aviation industry that American Airlines had left its competitors at the starting gate. Together with American Airlines' decision to announce the DC-10 order, it was also reported that American Airlines had declared its intention to have the British Rolls-Royce RB211 turbofan engine on its DC-10 aircraft.
The DC-10 was first ordered by launch customers American Airlines with 25 orders, and United Airlines with 30 orders and 30 options in 1968. The first DC-10, a series 10, made its maiden flight on August 29, 1970. Following a test program with 929 flights covering 1,551 hours, the DC-10 received its type certificate from the FAA on July 29, 1971. It entered commercial service with American Airlines on August 5, 1971 on a round trip flight between Los Angeles and Chicago. United Airlines then began DC-10 services in mid-August. American's DC-10s had 206 seats and United's had 222; both had six-across seating in first-class and eight-across (four pairs) in coach. The DC-10's similarity to the Lockheed L-1011 in design, passenger capacity, and launch date resulted in a sales competition that affected profitability of the aircraft.
The first DC-10 version was the "domestic" series 10 with a range of 3,800 miles (3,300 nmi, 6,110 km) with a typical passenger load and a range of 2,710 miles (2,350 nmi, 4,360 km) with maximum payload. The series 15 had a typical load range of 4,350 miles (3,780 nmi, 7,000 km). The series 20 was powered by Pratt & Whitney JT9D turbofan engines, whereas the series 10 and 30 engines were General Electric CF6. Before delivery of its aircraft, Northwest's president asked that the "series 20" aircraft be redesignated "series 40" because the aircraft was much improved over the original design. The FAA issued the series 40 certificate on October 27, 1972.
The series 30 and 40 were the longer-range "international" versions. The main visible difference 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 an additional centerline main gear. The center main two-wheel landing gear (which extends from the center of the fuselage) was added to distribute the extra weight and for additional braking. The series 30 had a typical load range of 6,220 mi (10,010 km) and a maximum payload range of 4,604 mi (7,410 km). The series 40 had a typical load range of 5,750 miles (9,265 km) and a maximum payload range of 4,030 miles (3,500 nmi, 6,490 km).
The DC-10 had two engine options and introduced longer-range variants a few years after entering service; these allowed it to distinguish itself from its main competitor, the L-1011. The 446th and final DC-10 rolled off the Long Beach, California Products Division production line in December 1988 and was delivered to Nigeria Airways in July 1989. The production run exceeded the 1971 estimate of 438 deliveries needed to break even on the project. As the final DC-10s were delivered McDonnell Douglas had started production of its successor, the MD-11.
In the late 1980s, as international travel was growing due to lower oil prices and more economic freedom, widebody demand could not be met by the delayed Boeing 747-400, MD-11 and the Airbus A330/A340 while the B747-200/300 and DC-10 production ended, and the used DC10-30s value nearly doubled from less than $20 million to nearly $40 million.
The DC-10 is a low-wing cantilever monoplane, powered by three turbofan engines. Two engines are mounted on pylons that attach to the bottom of the wings, while the third engine is encased in a protective banjo-shaped structure that is mounted on the top of the rear fuselage. The vertical stabilizer with its two-segment rudder, is mounted on top of the tail engine banjo. The horizontal stabilizer with its four-segment elevator is attached to the sides of the rear fuselage in the conventional manner. The airliner has a retractable tricycle landing gear. To enable higher gross weights, the later -30 and -40 series have an additional two-wheel main landing gear, which retracts into the center of the fuselage.
It was designed for medium to long-range flights that can accommodate 250 to 380 passengers, and is operated by a cockpit flight crew of three. The fuselage has underfloor storage for cargo and baggage.
The KDC-10 is an aerial refueling tanker for the Royal Netherlands Air Force. These were converted from civil airliners (DC-10-30CF) to a similar standard as the KC-10. Also, commercial refueling companies Omega Aerial Refueling Services and Global Airtanker Service operate two KDC-10 tankers for lease. Four have been built.
The MD-10 is a retrofit cockpit upgrade to the DC-10 and a re-designation to MD-10. The upgrade included an Advanced Common Flightdeck (ACF) used on the MD-11 and was launched in 1996. 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 FedEx Express, which operate both the MD-10 and MD-11, to have a common pilot pool for both aircraft. The MD-10 conversion now falls under the Boeing Converted Freighter program where Boeing's international affiliate companies perform the conversions.
In July 2019, there were 31 DC-10s and MD-10s in airline service with operators FedEx Express (30), and TAB Airlines (1). On January 8, 2007, Northwest Airlines retired its last remaining DC-10 from scheduled passenger service, thus ending the aircraft's operations with major airlines. Regarding the retirement of Northwest's DC-10 fleet, Wade Blaufuss, spokesman for the Northwest chapter of the Air Line Pilots Association said, "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." Biman Bangladesh Airlines was the last commercial carrier to operate the DC-10 in passenger service. The airline flew the DC-10 on a regular passenger flight for the last time on February 20, 2014, from Dhaka, Bangladesh to Birmingham, UK. Local charter flights were flown in the UK until February 24, 2014.
Non-airline operators include the Royal Netherlands Air Force with two DC-10-30CF-based KDC-10 tanker aircraft, the USAF with its 59 KC-10s, and the 10 Tanker Air Carrier with its modified DC-10-10 used for fighting wildfires. Orbis International has used a DC-10 as a flying eye hospital. Surgery is performed on the ground and the operating room is located between the wings for maximum stability. In 2008, Orbis chose to replace its aging DC-10-10 with a DC-10-30 jointly donated by FedEx and United Airlines. The newer DC-10 converted into MD-10 configuration, and began flying as an eye hospital in 2010. One former American Airlines DC-10-10 is operated by the Missile Defense Agency as the Widebody Airborne Sensor Platform (WASP).
As of September 2015, the DC-10 had been involved in 55 accidents and incidents, including 32 hull-loss accidents, with 1,261 occupant fatalities. Of these accidents and incidents, it has been involved in nine hijackings resulting in one death and a bombing resulting in 170 occupant fatalities. Despite its poor safety record in the 1970s, which gave it an unfavorable reputation, the DC-10 has proved to be a reliable aircraft with a low overall accident rate as of 1998. The DC-10's initially poor safety record has continuously improved as design flaws were rectified and fleet hours increased. The DC-10's lifetime safety record is comparable to similar second-generation passenger jets as of 2008.
The DC-10 was designed with cargo doors that opened outward instead of conventional inward-opening "plug-type" doors. Using outward-opening doors allowed the DC-10's cargo area to be completely filled, since the door was not occupying usable interior space when open. To secure the door against the outward force from the pressurization of the fuselage at high altitudes, outward-opening doors must use heavy locking mechanisms. In the event of a door lock malfunction, there is great potential for explosive decompression.
A problem with the outward-opening cargo door first became publicly known on June 12, 1972, when American Airlines Flight 96 lost its aft cargo door shortly after takeoff from Detroit Metro Airport, in flight above Windsor, Ontario. Before Flight 96 took off, an airport employee had forced the door shut. Due to the cargo door's design, the door appeared to be securely locked despite the internal locking mechanism not being fully engaged. Subsequently, when the aircraft reached approximately 11,750 feet (3,580 m) in altitude, the rear cargo door blew out, causing an explosive decompression that created a large pressure differential between the cabin above and the cargo bay below, causing the cabin floor to collapse. This collapsed section of the floor cut or impeded many of the control cables to the empennage control systems necessary to fly the aircraft, which were routed through the floor beams, leaving the pilots with very limited control of the aircraft. The crew performed an emergency landing by using the ailerons, right elevator, some limited rudder trim, and asymmetrical thrust of the wing engines. All 67 passengers evacuated safely.
During the investigation of the near-crash of Flight 96, U.S. National Transportation Safety Board (NTSB) investigators found that the DC-10's cargo door design was dangerously flawed. The door relied on a set of heavy steel hooks to secure it against the door frame. When the hooks were fully engaged, an outside lever on the cargo door could be depressed to drive a set of locking pins through the hooks to hold them in place. The NTSB investigation found that it was possible to close the outside lever without the hooks being fully engaged, and there would be no outward signs that the locking mechanism was not engaged; the cargo-door indicator in the cockpit would still register the door as being secured without hooks and locking pins being in the closed position. This combination of factors caused Flight 96 to take off without its aft cargo door being fully locked. Following the Windsor accident investigation, the NTSB made several recommendations, including repairing the faulty cargo door design to make it impossible for baggage handlers to close the cargo door lever without the locking pins being fully engaged. It was also recommended that vents be installed in the cabin floor, so that in case of an explosive decompression, the pressure difference between the cabin and cargo bay could quickly be equalized without collapsing the cabin floor and damaging critical control systems. Although many carriers voluntarily modified the cargo doors, no airworthiness directive was issued to require reworking of the locking system, due to a gentlemen's agreement between the head of the FAA, John H. Shaffer, and the head of McDonnell Douglas's aircraft division, Jackson McGowen. McDonnell Douglas did make modifications to the cargo door, but the basic design remained unchanged and problems persisted.
On March 3, 1974, an almost identical cargo-door blowout caused Turkish Airlines Flight 981 to crash into a forest near the town of Ermenonville, France, shortly after leaving Paris. All 346 people on board died; it was one of the deadliest air crashes of all time. Circumstances of this crash were very similar to the previous accident. The cargo door had not been fully locked, though it appeared so to both cockpit crew and ground personnel. The Turkish aircraft had a different seating configuration that made the effects of decompression much more severe, which caused the aircraft's floor to collapse into the cargo bay. Control cables running through the floor beams were severed when the floor collapsed and rendered the aircraft uncontrollable. Crash investigators found that the DC-10's relief vents were not large enough to equalize the pressure between the passenger and cargo compartments during explosive decompression. Following this crash, a special subcommittee of the House of Representatives investigated the cargo-door issue and the FAA's certification of the original design. An airworthiness directive was issued, and all DC-10s underwent mandatory door modifications. The DC-10 experienced no more major incidents related to its cargo door after FAA-approved changes were made.
The DC-10 was involved in another deadly crash on May 25, 1979, when American Airlines Flight 191, departing Chicago's O'Hare Airport, went out of control immediately after takeoff. As the airliner rotated during its takeoff roll, the number one (left wing) engine and pylon assembly separated from the wing and swung upward over the top of the wing, severing critical hydraulic lines embedded in the wing's leading edge, as well as tearing away part of the wing structure. The loss of hydraulic pressure to the leading edge slat actuators caused the slats to retract due to aerodynamic forces, increasing the left wing's stall speed above the engine failure climb out speed being used by the pilots. With the left wing stalled and further destabilized by asymmetric thrust, the DC-10 rapidly rolled to the left, sharply descended, and crashed, killing all 271 people on board and two individuals on the ground. The loss of Flight 191 remains the deadliest aviation accident in U.S. history. The crash and its aftermath were widely covered by the media and dealt a severe blow to the DC-10's reputation and sales.
Following the crash, the FAA withdrew the DC-10's type certificate on June 6, 1979, which grounded all U.S. DC-10s. It grounded 138 U.S.-registered DC-10s, along with DC-10s from other nations with bilateral agreements with the United States, regarding aircraft certifications, and banned all other DC-10s from U.S. airspace. Even ferry flying within U.S. airspace was forbidden except to allow foreign air carriers to return their DC-10s to overseas maintenance bases. These measures were rescinded five weeks later on July 13, 1979, after modifications were made to the slat actuation and position systems, along with stall warning and power supply changes.
The National Transportation Safety Board (NTSB) officials discovered that a maintenance procedure was the cause of the accident. American Airlines mechanics had removed the engine and its pylon as a unit, rather than removing the engine from the pylon, then removing the pylon from the wing, as recommended by McDonnell Douglas. The faulty procedure was done using a forklift, which resulted in inadvertent structural damage. It was subsequently discovered that this short-cut procedure, believed to save many man-hours on maintenance, was being used by three major airlines, although McDonnell Douglas had advised against it. In November 1979, the Federal Aviation Administration (FAA) fined American Airlines $500,000 and Continental Airlines $100,000 for using this incorrect maintenance procedure.
The Flight 191 crash highlighted a major deficiency in the DC-10 design: its lack of a locking mechanism to maintain the position of the leading-edge slats in the event of a hydraulic or pneumatic actuation failure. The DC-10's design depended on the principle of hydrostatic lock to keep the slats extended against aerodynamic forces instead of a positive mechanical system, such as Acme screw actuation, to maintain slat position. It was determined that when the engine and pylon assembly pulled up and over the wing, it severed electrical wiring in the wing, thus rendering vital warning instruments in the cockpit inoperative.
In the wake of the grounding, the FAA convened a safety panel under the auspices of the National Academy of Sciences, to evaluate the design of the DC-10 and the U.S. regulatory system in general. The panel's report, published in June 1980, found "critical deficiencies in the way the Government certifies the safety of American-built airliners". This conclusion was echoed nearly 40 years later in the inquiries into the 2019 grounding of the Boeing 737 MAX.[verification needed]
Another major DC-10 crash was the United Airlines Flight 232 crash at Sioux City, Iowa, on July 19, 1989. The number two (tail) engine suffered an uncontained fan disk failure in flight, which damaged all three hydraulic systems and rendered the hydraulic flight controls inoperable. The flight crew, led by Captain Al Haynes and assisted by DC-10 flight instructor flying as a passenger (Dennis E. "Denny" Fitch), performed an emergency landing by constantly adjusting the thrust of the remaining two engines. The crew managed to fly the aircraft onto the runway in a partially controlled manner, and 185 of the 296 people on board survived (111 died) despite the destruction of the aircraft during the crash landing.
The DC-10 included no cable backup for the hydraulic-powered flight controls because it was considered nearly impossible for three hydraulic systems to fail during one flight, and that the control surfaces were too large to be moved without hydraulic assistance. All three hydraulic systems were in close proximity, directly beneath the tail engine. The #2 engine explosion hurled fragments that ruptured all three lines, resulting in total loss of control to the elevators, ailerons, spoilers, horizontal stabilizer, rudder, flaps and slats.
Following the UAL 232 accident, hydraulic fuses were installed in the #3 hydraulic system in the area below the #2 engine on all DC-10 aircraft to ensure that sufficient control capability remained if all three hydraulic system lines should be damaged in the tail area. It is still possible to lose all three hydraulic systems elsewhere. This nearly happened to a cargo airliner in 2002 during takeoff when a main-gear tire exploded in the wheel well. The damage in the left wing area caused total loss of pressure from the #1 and the #2 hydraulic systems. The #3 system was dented but not penetrated.
Other notable accidents are:
|Std. seating||270 (222Y 8-abreast @ 34" + 48J 6-abreast @ 38")|
|Max. seating||399Y (10-abreast @ 29-34" pitch) layout, FAA exit limit: 380|
|Cargo||26 LD3 layout, main deck: 22 88×125″ or 30 88x108″ pallets|
|Length||182 ft 3.1 in / 55.55 m||181 ft 7.2 in / 55.35 m||182 ft 2.6 in / 55.54 m|
|Height||57 ft 6 in / 17.53 m||57 ft 7 in / 17.55 m|
|Wingspan||155 ft 4 in / 47.35 m||165 ft 4 in / 50.39 m|
|Wing area||3,550 sq ft (330 m2)||3,647 sq ft (338.8 m2)|
|Width||19 ft 9 in (6.02 m) fuselage, 224 in (569 cm) interior|
|OEW (pax)||240,171 lb / 108,940 kg||266,191 lb / 120,742 kg||270,213 lb / 122,567 kg|
|MTOW||430,000 lb / 195,045 kg||555,000 lb / 251,744 kg|
|Max. payload||94,829 lb / 43,014 kg||101,809 lb / 46,180 kg||97,787 lb 44,356 kg|
|Fuel capacity||21,762 US gal / 82,376 L||36,652 US gal / 137,509 L|
|Engines ×3||GE CF6-6D||GE CF6-50C||PW JT9D-59A|
|Thrust ×3||40,000 lbf / 177.92 kN||51,000 lbf / 226.85 kN||53,000 lbf / 235.74 kN|
|Cruise||Mach 0.82 (473 kn; 876 km/h) typical, Mach 0.88 (507 kn; 940 km/h) MMo|
|Range[a]||3,500 nmi (6,500 km)||5,200 nmi (9,600 km)||5,100 nmi (9,400 km)|
|Takeoff[b]||9,000 ft (2,700 m)||10,500 ft (3,200 m)||9,500 ft (2,900 m)|
|Ceiling||42,000 ft (12,800 m)|
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