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The DC-8 Super Seventy Series

The end of the line

May 12, 1972

On May 12, 1972, the final DC-8, a model -63 for SAS, was delivered from the Long Beach factory.  As was the case with all early jetliners, it was  noisy by modern standards.  With expanding jet fleets going into service at the time, aircraft noise was increasingly becoming a serious problem. Because of their increased takeoff weights and higher thrust, the new 60-series DC-8s, in particular, prompted legislation for aircraft noise standards in many countries. The New York Port Authority (search) had already adopted takeoff weight restrictions aimed at the stretched DC-8s.

Douglas, now a division of McDonnell Douglas, had committed to build the new DC-10 in 1968.  With high bypass ratio engines, the new wide-body transports could easily meet existing and proposed noise limits. The company  was unable to  commit further investment to modify existing DC-8s even as several airlines had enquired about noise reduction alternatives.

Aftermarket hushkits were offered by third parties, but while they represented a lower investment for the operators, they were only marginally effective at noise abatement and caused some performance degradation.  A better solution was to re-engine late model Series 60 airframes.  United, Flying Tigers, and Delta joined to begin a joint study of re-engine options.  A newer engine would mean a increase in efficiency and performance at the same time it would deliver an acceptable noise output. There were three suitable engine choices - the Pratt and Whitney JT8D-200, the IAE V-2500, and the General Electric - Snecma CFM56.  In 1977, several retired McDonnell Douglas executives led by Jack McGowen, formed Cammacorp as a contractor for DC-8 conversions and retrofitting projects. With the concurrent approval of the airlines and the considerable participation of GE, Cammacorp selected the CFM-56 engine to power the modified DC-8s. As well as being 70% quieter and more powerful, the CFM56 was roughly 20% more fuel efficient than the JT3D, thereby reducing operating costs and extending the range of the aircraft.

The program to re-engine the DC-8 was launched in 1979 after United Airlines ordered conversion of its DC-8-61s. Delta and Flying Tiger followed soon thereafter. The conversion program was extended to other Series 60  aircraft, which were renamed the -71, -72, and -73. 

MDC acted as a vendor to Cammacorp, providing engineering data and design consulting on a contracted basis.  Airframe modifications were done at the McDonnell Douglas plant in Tulsa. Grumman Aerospace was contracted to supply engine nacelles and the redesigned pylons that were required for the new engine.

First flight took place  on August 15, 1981. Flight test proved that the re-engined DC-8 met or exceeded performance and noise level estimates. First delivery took place in March, 1982.

A total of 110 Super -70s were delivered: 53 -71's, 7 -72's, and 50 -73's. The final airplane off the line was a -72 for NASA in 1986 after which Cammacorp closed its doors.  Product support is provided by the participants in the program.