| DC-10 | |
|---|---|
| A DC-10-30 of Ariana Afghan Airlines lands at London Heathrow Airport in 1980. | |
| Role | Wide-body jet airliner |
| National origin | United States |
| Manufacturer | McDonnell Douglas |
| First flight | August 29, 1970 |
| Introduction | August 5, 1971 with American Airlines |
| Status | Out of production, In service |
| Primary users | FedEx Express Omni Air International Biman Bangladesh Airlines |
| Produced | 1968–1988 |
| Number built | DC-10: 386[1] KC-10: 60[1] |
| Variants | KC-10 Extender |
| Developed into | McDonnell Douglas MD-11 |
The McDonnell Douglas DC-10 is a three-engine widebody jet airliner manufactured by McDonnell Douglas. The DC-10 has range for medium- to long-haul flights, capable of carrying a maximum 380 passengers. Its most distinguishing feature is the two turbofan engines mounted on underwing pylons and a third engine at the base of the vertical stabilizer. The model was a successor to McDonnell Douglas's DC-8 for long-range operations, and competed in the same markets as the Lockheed L-1011 Tristar, which has a similar layout 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.[2] The largest operator of the DC-10 is US cargo airline FedEx Express. The DC-10 was succeeded by the related McDonnell Douglas MD-11. McDonnell Douglas, then Boeing after the two companies merged, upgraded some DC-10s with glass cockpits and renamed them MD-10s.
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Following an unsuccessful proposal for the US 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.[3]
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.[4][5] The DC-10, a series 10 model, made its first flight on August 29, 1970.[6] Following a flight test program with 929 flights covering 1,551 hours, the DC-10 was awarded a type certificate from the FAA on July 29, 1971.[7] It entered commercial service with American Airlines on August 5, 1971 on a round trip flight between Los Angeles and Chicago. United Airlines began DC-10 service on August 16, 1971.[8] The DC-10's similarity to the L-1011 in terms of passenger capacity and launch in the same timeframe resulted in a head to head sales competition which 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).[9][10] 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.[11]
The series 30 and 40 were the longer range "international" versions. 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 gear (one front, three main). The center main two-wheel landing gear (which extends from the center of the fuselage) was added to accommodate the extra weight by distributing the weight and providing 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).[9][12]
Eventually, the DC-10 was able to distinguish itself from its competitors with two engine options, as well as earlier introduction of longer range variants than the L-1011. The 446th and final DC-10 rolled off the production line in December 1988 and was delivered to Nigeria Airways in July 1989.[13] The DC-10 was assembled at McDonnell Douglas's Douglas Products Division in Long Beach, California.[2] As the final few DC-10 deliveries were occurring, McDonnell Douglas had already started production of the DC-10's successor, the MD-11.[14]
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 and 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.[15]
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 stowage for cargo and baggage.[16]
The KC-10 Extender is a military version of the DC-10-30CF for aerial refueling. The aircraft was ordered by the U.S. Air Force and delivered from 1981 to 1988. A total of 60 were built.[29]
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 Air and Global Airtanker Service operate two KDC-10 tanker for lease. Four have been built.[30][31]
The 10 Tanker Air Carrier is a DC-10-10 converted into a firefighting tanker aircraft, using modified water tanks from Erickson Air-Crane.
The MD-10 is 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.[32] 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.[33]
On January 8, 2007, Northwest Airlines retired its last remaining DC-10 from scheduled passenger service, replacing it with an Airbus A330 for a route between Minneapolis-St. Paul and Honolulu,[34] 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."[35] "The DC-10 is going to be remembered as a better cargo plane than passenger plane," said Richard Aboulafia, an analyst with the Teal Group.[35] In November 2006 ATA Airlines announced that they had purchased seven of Northwest's remaining DC-10s to replace their Lockheed L-1011s. Omni Air International purchased six of Northwest's DC-10 aircraft.[36]
The aging models are now largely used as dedicated freight aircraft. American Airlines and United Airlines sold their large DC-10-10 fleets to cargo carrier FedEx. Many 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 and cargo services with their three-person flight deck configuration. Omni Air International and World Airways continue to operate the DC-10 on charter passenger services as well as for the Air Mobility Command. Biman Bangladesh Airlines operates five DC-10-30s as one of their primary passenger aircraft as of 2009.[37]
Non-airline operators include the Royal Netherlands Air Force with three 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.[38] Orbis International has used a single DC-10-10 converted into a flying eye hospital. Surgery is performed on the ground and the operating room is located between the wings for maximum stability.[39] Orbis chose to replace its aging DC-10 with a MD-10,[40] that was converted from a DC-10 jointly donated by FedEx and United Airlines.[41] The MD-10 eye hospital is expected to be flying in 2010.[41][42] Additionally, one former American Airlines DC-10-10 is operated by the Missile Defense Agency as the Widebody Airborne Sensor Platform (WASP).[43]
In January 2011, there were 97 DC-10s in service with commercial operators FedEx Express (74), Omni Air International (8), Biman Bangladesh Airlines (4), Cielos Airlines (3), Kelowna Flightcraft Air Charter (3), and others with fewer aircraft.[44]
As of February 2011, the DC-10 was involved in 56 incidents,[45] including 31 hull-loss accidents,[46] with 1,261 fatalities.[47]
Despite its troubled beginnings in the 1970s, which gave it an unfavorable reputation,[48] the DC-10 has proved a reliable aircraft.[49] The DC-10's initially poor safety record continuously improved as design flaws were rectified and fleet hours increased.[49] The DC-10's lifetime safety record is comparable to similar second-generation passenger jets as of 2008.[50]
The DC-10 was designed with cargo doors that opened outward instead of conventional inward-opening "plug-type" doors which, due to their being larger than the door frame, make opening the door impossible once the plane is pressurized. Using outward-opening doors allowed the DC-10's cargo area to be completely filled since the door was not occupying usable space. To secure the door against the outward force caused by the pressurization of the fuselage at high altitudes, outward-opening doors must rely on heavy locking mechanisms. In the event of a door lock malfunction, there is great potential for explosive decompression.[51]
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, Michigan. Before Flight 96 took off, an airport employee had forced the door shut, which, due to the cargo door's design, gave an outward appearance of being securely locked despite the internal locking mechanism not being fully engaged. Subsequently, when the plane reached approximately 11,750 feet (3,580 m) in altitude, the cargo door blew out, causing an explosive decompression which partially collapsed the cabin floor at the rear of the plane. This collapsed section of the floor cut or impeded many of the control cables to the empennage control systems necessary to fly the plane.[52][53] The crew was able to accomplish an emergency landing by using the ailerons, right elevator, some limited rudder trim and asymmetrical thrust of the wing engines.[54]
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, which drives a set of locking pins through the hooks, holding 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. Even though the hooks and locking pins were not in the closed position, the cargo door indicator in the cockpit would still register the door as being secured. This combination of factors caused Flight 96 to take off without its aft cargo door being fully locked. And when the door blew out at altitude, the sudden decompression of the airplane caused a large pressure difference to build up between the cabin above and the cargo bay below. This depressurization loading is what caused the cabin floor to collapse.[55] And because the DC-10 was designed with its hydraulics and control wires routed through the floor beams, the collapse of the cabin floor caused a loss of vital flight controls.[52]
Following the Windsor incident 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.[55] 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 and McDonnell Douglas. McDonnell Douglas did make modifications to the cargo door, but the basic design remained unchanged and problems persisted.[55]
On March 3, 1974, an almost identical cargo door blow-out caused Turkish Airlines Flight 981 to crash into a forest near the town of Ermenonville, France shortly after leaving Paris.[55] 346 people were killed[56] in 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 exacerbated the effects of decompression, which caused the aircraft's floor 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.[55] 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.[56] 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.[57] An airworthiness directive was issued, and all DC-10s underwent mandatory door modifications.[57] The DC-10 experienced no more major incidents related to its cargo door after FAA-approved changes were made.[55]
The DC-10 experienced another major accident with the crash of American Airlines Flight 191 on May 25, 1979. Flight 191 lost its number one (left wing) engine after taking off from O'Hare International Airport in Chicago, USA.[58] As the engine separated upwards, it ripped through the leading edge of the wing, rupturing hydraulic lines. Without hydraulic pressure, the left wing leading edge slats retracted due to the force of the air moving over the wings. That, in turn, increased the stall speed of the left wing above the engine failure climb out speed being used by the pilots. When the left wing stalled, the plane rapidly rolled to the left and crashed before the flight crew could recover. All 271 people on board, plus two on the ground, were killed.[59]
The United States National Transportation Safety Board (NTSB) officials discovered that a maintenance procedure was the culprit. American Airlines mechanics removed the engine and its pylon together, rather than removing the engine from the pylon then the pylon from the wing, as recommended by McDonnell Douglas. This was done using a forklift and the pylon was inadvertently cracked in the process. The short-cut procedure, believed to save many man hours on maintenance, was used by three major airlines, although McDonnell Douglas advised against it.[60] In November 1979, the Federal Aviation Administration (FAA) fined American Airlines $500,000 for using this faulty maintenance procedure. Continental Airlines was fined $100,000 on a similar charge.[60][61]
The Chicago accident also 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 failure.[60] Other wide-body aircraft of the day carried such a feature. Another deficiency highlighted in the NTSB report was the vulnerable placement of wiring at the leading-edge (front) of the wing. When the engine pulled up and over the wing, it tore out these lines, thus rendering vital warning instruments in the cockpit inoperable. Following the Chicago crash, the type certificate of the DC-10 was withdrawn by the FAA, grounding the aircraft on June 6, 1979. The aircraft resumed service after modifications were made to the slat actuation systems and position systems, along with stall warning and power supply changes.[62]
Another major DC-10 crash was United Airlines Flight 232 disaster at Sioux City, Iowa, USA, 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 a senior pilot 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 in spite of the destruction of the plane during that landing.[63]
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. However, all three hydraulic systems were in close proximity, directly beneath the tail engine. The #2 engine explosion hurled shrapnel that ruptured all three lines, resulting in total loss of control to the elevators, ailerons, spoilers, horizontal stabilizer, rudder, flaps and slats.[63]
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. That nearly occurred 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 in the #1 and the #2 hydraulic systems. The #3 system was dented but not penetrated.[64]
Other notable incidents and accidents involving the DC-10 are listed below.
The Air France Concorde crash of 2000 was attributed to a fragment of titanium that fell from the thrust reverser of a Continental Airlines DC-10 that had taken off some four minutes earlier. This fragment was traced to a third party parts replacement which had not been approved by the FAA.
| DC-10-10 | DC-10-15 | DC-10-30 | DC-10-40 | |
|---|---|---|---|---|
| Cockpit crew | Three | |||
| Passengers | 399 (maximum), 255 (2 class, typical) | |||
| Cargo (freighter variant) | 22 LD7 pallets | 23 LD7 pallets | ||
| Fuselage length | 170 ft 6 in (51.97 m) | |||
| Height | 58 ft 1 in (17.7 m) | |||
| Wingspan | 155 ft 4 in (47.34 m) | 165 ft 4 in (50.4 m) | ||
| Fuselage width | 19 ft 9 in (6.02 m) | |||
| Fuselage height | 19 ft 9 in (6.02 m) | |||
| Max interior width | 18 ft 2 in (5.54 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) |
| Typical cruise speed | Mach 0.82 (564 mph, 908 km/h, 490 kt) |
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| Max cruise speed | Mach 0.88 (610 mph, 982 km/h, 530 kt) |
|||
| Max range, loaded | 3,800 miles (6,114 km) | 4,350 mi (7,000 km) | 6,600 mi (10,620 km) | 5,750 mi (9,252 km) |
| Maximum 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) |
| Takeoff run on MTOW | 8,612 ft (2,625 m) | 7,257 ft (2,212 m) | 9,341 ft (2,847 m) | 9,242 ft (2,817 m) |
| 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) |
| 1971 | 1972 | 1973 | 1974 | 1975 | 1976 | 1977 | 1978 | 1979 | 1980 | 1981 | 1982 | 1983 | 1984 | 1985 | 1986 | 1987 | 1988 | 1989 | Total |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 13 | 52 | 57 | 48 | 42 | 19 | 14 | 18 | 36 | 40 | 25 | 11 | 12 | 10 | 11 | 17 | 10 | 10 | 1 | 446 |
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