If the Air Force does not begin to replace the fleet now, the service may end up flying many of these tankers, which lack defenses and other systems, for another 40 years, senior officers said at a House Armed Services Projection Forces Subcommittee hearing.
"Eighty years will be a very, very old aircraft," said Lt. Gen. Donald Hoffman, the service's top acquisition officer.
The planes, officers said, are aging and experiencing problems that could hinder operations. Air cycling motors, for instance, are breaking and the shrapnel from those motors threaten to land in a main fuel tank.
"They are not modern airplanes," said Lt. Gen. Christopher Kelly, vice commander of Air Mobility Command, who emphasized that the fleet, which has been in service since 1957, is the oldest in the Air Force.
Meanwhile, the cost of maintaining the fleet is increasing rapidly as the planes' capabilities decline.
Retiring 114 of the oldest models by 2010 would save the Air Force $6.1 billion, about the cost of 50 new tanker aircraft, according to written testimony. And Air Force forecasts maintaining the 531 KC-135s would cost $46.8 billion through 2040.
The House panel called the hearing to review a so-called tanker analysis of alternatives, conducted by RAND Corp. with input from the Pentagon. The study did not urge the Air Force to replace the tankers immediately, and found the service should weigh operational and technical risks, as well as affordability, before moving forward.
The Air Force intends to move quickly and issue a "request for information" to the aviation industry as soon as Pentagon leaders bless the analysis, Hoffman told reporters. That would be followed by formal request for proposals, sent to the industry as early as this fall.
The service plans to consider a wide range of options spelled out in the RAND report, including buying new commercial aircraft or upgrading older airframes. Kelly pledged that a future tanker contract would involve "fair and open competition of all alternatives."
In the rush to acquire new planes in 2003, the Air Force tried to lease Boeing KC-767s before reviewing other options. The $23.5 billion deal collapsed after congressional critics, led by Sen. John McCain, R-Ariz., forced the Pentagon to consider alternatives to the Boeing aircraft and open future tanker contracts to competition.
The Defense Department had planned to brief Congress on the classified study last February. But those briefings were postponed until late January to allow RAND more time review the tanker requirements and options.
Considered the biggest Pentagon procurement scandal in more than two decades, the original tanker-lease deal prompted the resignation of Air Force Secretary James Roche and convictions of two Boeing executives, ex-Air Force acquisition official Darleen Druyun and Michael Sears, the company's chief financial officer.