McDonnell Douglas DC-10
The McDonnell Douglas DC-10 is a three-engine widebody jet airliner carrying up to 380 passengers on medium-range and long-haul flights.
In 1967 Douglas merged with McDonnell and the DC-10 became the first commercial airliner developed by the new company McDonnell Douglas. Douglas was one of the losers in the US Air Force's CX-HLS competition for a large cargo plane, which resulted in the Lockheed C-5A Galaxy. Like Boeing it sought ways to use the results of CX-HLS research for a big airliner. Boeing developed the 747, McDonnell Douglas the DC-10.
Early designs showed a four-engined double-deck airplane seating up to 550 passengers, but later the aircraft manufacturer decided to build a three-engined single-deck aircraft seating up to 380 passengers. Launch customers were American Airlines with 25 orders and United Airlines with 30 orders (plus 30 options).
The DC-10 made its maiden flight on 29 August 1970 (Photo: Boeing) and the FAA granted type certification on 29 July 1971. American Airlines introduced the DC-10 into commercial service on 5 August 1971 between Los Angeles and Chicago. United Airlines followed on 16 August.
The DC-10 competed head-on with the Lockheed L-1011 TriStar, which offered the same capacity and, with two engines under the wing and one in the tail, looked much like the Douglas widebody. The main visual difference is the way the tail engine is installed. The TriStar's engine is at the end of the fuselage and air is led to its inlet via an S-duct through the tail. The DC-10 has the engine in a straight duct, placed above the rear of the fuselage.
The first DC-10s were delivered with eight-abreast economy seating (2+4+2). Later, when competition between the airlines intensified, nine-abreast seating (2+5+2, sometimes 3+4+2) became the standard. Some airlines even introduced ten-abreast seating (3+4+3).
Douglas offered several versions. The first was the DC-10-10, intended for (US) domestic services. It was fitted with General Electric CF6 turbofans. The DC-10-10CF was a convertible passenger/cargo variant. The DC-10-15 had more powerful CF6-50C2F turbofans for operations at hot and high airports. It attracted orders from two Mexican carriers, Mexicana and Aeroméxico, for a total of seven aircraft.
The series 30 is a longer-range intercontinental version. This is a much heavier aircraft and to carry the extra weight it has an extra two-wheel landing gear leg under the fuselage. It is fitted with more powerful General Electric CF6-50 turbofans and has extra fuel capacity to achieve intercontinental range. This version became particularly popular among European airlines to complement their 747-fleets. Swissair and KLM started flying the DC-10-30 in November 1972. Variants are the DC-10-30CF convertible cargo/passenger aircraft, the DC-10-30ER with extended range and the DC-10-30F freighter.
The DC-10-40 (initially designated 'DC-10-20') became powered by Pratt & Whitney JT9D turbofans and was actually the first long-haul version. Like the DC-10-30 it has an extra main landing gear leg. The only customers were Northwest Orient Airlines and Japan Airlines. McDonnell Douglas changed the designation from 'DC-10-20' to 'DC-10-40' after a special request from Northwest. The airline wanted to emphasize that the aircraft was much improved compared with the earliest DC-10 versions.
The DC-10-50 was a proposal to British Airways with Rolls-Royce RB211-524 engines, but BA chose the Lockheed L-1011 TriStar instead and this version was never built. Another never produced version was the smaller DC-10 Twin, with two CF6 engines, an aircraft in the same class as the Airbus A300.
The KC-10A Extender is a tanker version for in-flight refuelling of which McDonnell Douglas built sixty for the US Air Force. Some civil DC-10-30CFs have been converted into tanker aircraft as well (for example the KDC-10 for the Royal Netherlands Air Force). One DC-10 has been converted into a firefighting aircraft. Orbis International, an international non-profit non-governmental organisation, flies a DC-10 as flying eye hospital to provide eyecare in developing countries.
'MD-10' is the designation of converted DC-10s with a renewed, two-crew electronic flight deck like that of the MD-11, without a flight engineer position. Type rating for pilots is common with the MD-11. Launch customer Federal Express ordered the conversion of seventy DC-10s.
In 1979 Douglas published details of possible stretched versions, the so-called DC-10 Series 61, 62 and 63, designated analogous to the earlier DC-8 stretches into DC-8-61, -62 and -63. The DC-10-61 and DC-10-63 would be stretched 12,2 m (40 ft) and the DC-10-62 8.14 m (26.7 ft). The 61 would have the basic DC-10-30 wing and the 62 and 63 would get an extended and improved wing. The 'Super Sixties'-versions weren't built however. Late in 1982 McDonnell Douglas changed the 'DC'-designation to 'MD' and in 1985 it started studies on a stretched DC-10 as 'MD-11X', with a 6.78 m (22 ft 4 in) longer fuselage. This became the later MD-11.
During the 1970s and 1980s the DC-10 became involved in several major accidents due to shortcomings in the design of the aircraft. Because of a design fault the cargo doors didn't close correctly and in 1974 346 passengers and crew died when a THY Turkish Airlines DC-10 departing from Paris Orly crashed after a door opened in flight. Demanded by the FAA McDonnell Douglas redesigned the door and added small windows through which ground crew could visually verify that the latch pins of the door were properly engaged after closure.
Another deficiency was the lack of a mechanism to lock the leading-edge slats on the wing in the case of hydraulic failure. This led to the crash of an American Airlines DC-10 on 25 May 1979. The left engine broke off and damaged hydraulic lines of the wings's leading slats. Because there was no lock-mechanism, the slats retracted due to the force of the air, the left wing stalled and the aircraft crashed, killing 271 people on board plus two on the ground. The FAA grounded the DC-10 on 6 June 1979. The flying ban was lifted on 13 July after modification of the slat system. The primary cause of the breaking off of the engine was not a design fault, but were faulty maintenance procedures with American Airlines and also with Continental Airlines. Mechanics removed the engine and its pylon together, instead of first removing the engine from the pylon and then the pylon itself from the wing. This happened with a forklift and the pylon was cracked during this process.
The crash of a United Airlines DC-10 on 19 July 1989 at Sioux City Airport after an uncontained disk failure in the tail engine showed the vulnerability of the DC-10's threefold hydraulic systems. The systems were close together and all three became damaged and inoperable. The flight crew tried to land the aircraft by continuously adjusting the thrust on the remaining two engines. Still, the aircraft crashed, but 185 of the 296 people on board survived. Modifications were inevitable.
After all improvements the DC-10 became a much safer aircraft during its later years of operation. Douglas produced the DC-10 until 1988 after building 386 DC-10s plus 60 KC-10 Extender aerial tanker aircraft for the US Air Force. The final aircraft was delivered to Nigeria Airways. The aircraft type was replaced on the assembly line by the MD-11.
Early in 2015 about sixty DC-10s are still in airline service as cargo aircraft, almost all of them with Federal Express. Biman Bangladesh Airlines was the last airline to operate scheduled passenger flights with the DC-10, until 20 February 2014, when it performed the final scheduled passenger flight from its homebase Dhaka to Birmingham (UK).
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