September 21, 2009: The U.S. Air Force is going to try, one more time, to find a suitable replacement for its aging KC-135 aerial tankers. Over the last few years, attempts to select a replacement have run afoul of incompetence, politics, lawyers, and a bit of corruption. Meanwhile, the 1950s era KC-135s are becoming more expensive to maintain. Currently, it costs $2 billion a year to keep them flying. But in ten years, this will triple to $6 billion a year. Old jets never get cheaper to maintain.

There are, for all practical purposes, two suitable replacements (the Boeing KC-767 and Airbus MRTT/KC-30) already flying. These two aircraft are being sold to air forces around the world. Last year, the U.S. Air Force selected the Airbus aircraft, which is based on the Airbus 330-300, which normally sells for $160 million each. The losing design, KC-767, being American, caused a stink in Congress, and questions about the selection process. So the decision was rescinded, and the air force was ordered to try again.

The KC-30 carries 20 percent more fuel than the KC-767, plus more cargo pallets (26 versus 19) and passengers. These were apparently decisive factors in the rescinded selection decision. Meanwhile, the KC-30 MRTT (Multi-Role Tanker Transport) is getting more orders worldwide, and may still win the USAF contract to replace the biggest tanker fleet on the planet.

The KC-767 is based on the Boeing 767-200 airliner, which sells for about $120 million. The 767 has been in service since 1982, and over 800 have been manufactured so far. Boeing developed the KC-767, at a cost of nearly a billion dollars, on its own. Boeing also developed the original KC-135 tanker in the 1950s, and has since built over 2,000 of these. But the KC-767 sales effort was marred by the earlier use of bribes and other misbehavior.

The winner of the competition will officially be known as the KC-45A, and will replace the four engine KC-135. The older aircraft carries 90 tons of fuel and can transfer up to 68 tons. Typically, aerial tankers have to service heavy bombers like the B-52, which carry over 140 tons of jet fuel, and fighters like the F-15 (over five tons). The KC-135 has long made itself useful carrying cargo and passengers, as well as fuel, and both the KC-767 and KC-30 have more capacity for this, with the KC-30 having a decisive edge.

The KC-767 was developed partly because it is about the same size as the KC-135 (wingspan is 156 feet, ten more than the KC-135). Thus the 767 could use the same basing and repair facilities as the 135. That was not a critical factor. Moreover, Airbus has been developing the KC-30 for several years, and the first entered service with Australia last year.

The contract to build 179 KC-45As is worth about $35 billion (about $196 million per aircraft). Airbus offered to do nearly half the work in the United States The first KC-45s were to enter service by 2012, rolling out of an assembly plant in the United States. But now it may be several years more before the half century old KC-135s begin getting replaced.