United DC-8s Pt6: Super 70s into the 80s

Despite rising fuel costs the Boeing 707 and Douglas DC-8 continued to form the nucleus of many of the major US trunk airline fleets throughout the 1970s and there was some surprise when American announced that it would retire all of its 707s by the end of 1981. All the other major trunks followed suit and the era of the first generation jets in front line service came to a close far more rapidly than anyone had thought it would. Unlike the 707 however the stretch DC-8s still had potential and would continue into the 1990s.

For the earlier parts in this series see:

United DC-8s Pt1: Jet Mainliners Into Service
United DC-8s Pt2: From Series 11s to 52s
United DC-8s Pt3: Jet Traders
United DC-8s Pt4: Long On Comfort
United DC-8s Pt5: Super 8s to the Aloha State

Deregulation was without a doubt a major factor in the retirement of the 707s and DC-8s. In the new cutthroat era of US aviation history airlines needed to be more efficient than ever to combat new start ups and build up their new hub and spoke networks. In addition the introduction of aircraft noise stages in 1977 by the FAA put a finite life on many of these aircraft as 707s and DC-8s fell within the noisiest Stage 1 category. Hushkitting large fleets of early 707s and DC-8s simply wasn't going to be cost effective.

United Air Lines Douglas DC-8-71 N8177U Gemini Jets 1:400 Scale Model Airliner

In fact noise was already an issue in the early 1970s and Douglas made various retrofit kits available to try and lessen the issue with the especially noisy series 60s. By early 1975 Douglas had identified several options to decrease the sound of a DC-8. First there was the possibility of a new version of the JT3B engine, but that would take 3 years to develop and cost about $6 million per plane. The alternative was to use de-rated CF-6 engines (as used on the DC-10) but these were even more expensive at $10 million per ship set and too powerful. In July 1975 General Electric offered the newer CFM-56 but in the absence of clear guidelines from government the airlines weren't keen to proceed.

N8090U in April 1984

In March 1977 things changed when the rules were set so that all aircraft weighing over 75,000 Ibs must meet Stage 3 regulations by January 3, 1985. This was a tough call as even early DC-9s, 727s, 737s and 747s didn't meet Stage 3 let alone 707s and DC-8s. That year a new company, Cammacorp, was  setup -   mainly by ex-Douglas staff. They agreed a deal with General Electric and SNECMA to market the CFM-56 engine for DC-8s. Despite McDonnell Douglas' initial reluctance to get involved by May 1977 it was negotiating with two airlines for a DC-8 re-engine. The two candidates were the CFM-56-1, de-rated to 22,000 Ibs of thrust, and the 19,000 Ib JT8D-209. The latter was to be the engine for the MD-80 series.

The JT8D had the advantage of not needing new pylons for DC-8-62/63s but in most other ways the CFM was the better engine. It had substantially reduced fuel burn (21% to 11.7%), shorter field length requirements, better range, higher cruise altitude and was quieter. It did need completely new pylons but these benefitted the DC-8-61 by removing the above wing portion of the pylon, as in the 62/63.

United Air Lines Douglas DC-8-71 N8177U Gemini Jets 1:400 Scale Model Airliner

Delta was the first airline to admit looking at the proposed re-engining however it was United that surprised the industry on March 29, 1979 when it placed a $400 million order to upgrade its 29 DC-8-61s with CFM-56-1 engines. United had initially favoured the JT8D but had been convinced to take a second look at the CFM by Flying Tigers. Cammacorp entered into an agreement with Douglas for it to provide all engineering support and undertake the conversions at its Tulsa plant.

The first aircraft to undergo conversion was United's N8093U, which arrived at Tulsa in October 1980. It was then that the change in designation from 61,62 or 63 to 71,72 or 73 was announced. The conversion period was longer than originally hoped and the first DC-8-71 missed the 1981 Paris Air Show and didn't fly until August 15. The FAA awarded type certification to the series 71 on April 13, 1981. The first aircraft delivered to United was N8092U on May 10, 1982. She went into service between San Francisco and Portland six days later. After one year United was averaging 16 hours a day of operations with the Super 70 fleet and dispatch reliability was running at 99.86%. United 71s were also fitted with the new widebody style interiors with enclosed overhead luggage compartments.

The DC-8 re-engine programme was a success for all concerned with 110 aircraft modified. More may have been rebuilt if it weren't for the US government's extension of noise restriction deadlines meaning that aircraft only needed to be Stage 2 compliant by January 1986 and Stage 3 compliant only by January 2000. This ruling favoured cheaper Stage 2 hushkits. In addition fuel prices had dropped and the conversion price had risen to $15 million per plane.

United got a good decade of extra service out of their DC-8-71s. The entire fleet was sold to GPA leasing in 1989 but was leased back for a few more years. The final service was operated in late 1991, fittingly between San Francisco and Kona, Hawaii. As late as December 1989 the United timetable still showed DC-8-71s operating a variety of trunk routes:

DEN - EWR HNL IAD LAX ORD PHL PDX SAN SFO
IAD - BDL DEN EWR ORD SAN SFO
LAX - EWR ORD PHL
ORD - BOS CLE CUN DEN EWR IAD LAX MIA PDX SFO SJO SEA
SFO - DEN, EWR IAD KOA LAX PDX SEA

N8096U at Vegas in August 1988

The DC-8-71 conversions were certainly good value for money and the type would go on to have long careers as freighters after Delta and United were done with them. This is the last part of my posts on United's DC-8s but there may yet be more on the DC-8-71...

References

Airliners.net. Final UA DC-8 Routes
Waddington, T. Great Airlines Series: Volume 2 - Douglas DC-8
Cearley, G.E. United: The Main Line Airway
Aeromoe's United Fleet