The US Air Force's fleet of 546 Boeing KC-135E/R/T Stratotanker in-flight refuelling aircraft are aged and increasingly expensive to support. But in the absence of a massive injection of funding, a replacement programme is unlikely in the near term. A recently approved US Congressional proposal to skirt this dilemma by leasing up to 100 Boeing 767 tankers has caused a political storm in Washington DC.

EADS, owner of 80% of Airbus, has cried foul because the defence bill specifies that a lease be negotiated solely with Boeing. In the face of criticism from Senator John McCain, who also sits on the Senate Armed Services Committee, the USAF has invited Airbus to submit data on an A330 alternative.

Given the post-11 September US political landscape and the strength of Boeing's lobby, few believe the A330 has much of a chance. Boeing has widened its congressional constituency by selecting its Wichita, Kansas, factory as the conversion site. EADS' strategy is to highlight Airbus as a viable and willing player in future military requirements while undermining Boeing's price.

As it stands, reaching a leasing agreement will prove a huge challenge, says a Boeing programme official, who also scoffs at the reported $26 billion cost of the10-year, 100-aircraft deal.

The defence bill prohibits the USAF making provision in the deal either to purchase or take delivery of the tankers at the end of the lease period, the full cost of which would otherwise have to be accounted for in the deal's first year. This does not stop the USAF negotiating to buy the aircraft later, but this would be a separate deal. Congress also has specified that the cost is no more than 90% of the 767's current price, with the lease limited to 10 years, and to include a one-year notice/liability early termination clause.

Of the USAF's 546 Stratotankers, all but 136 have been re-engined with CFM International CFM56-2s as KC-135R/Ts. The aircraft most in need of replacement are the remaining Pratt & Whitney TF33-102 powered KC-135Es. Last year, a General Accounting Office report said the Air Mobility Command's KC-135 fleet had an average mission-capable rate of less than 50% in Fiscal Year 2000, compared with 88% for the McDonnell Douglas KC-10 tanker and a wartime required rate of 85%.

Assuming Congress approves a deal with Boeing, the first aircraft will be not be delivered before 2004-5. Once at full rate, the USAF plans to absorb 20 767s a year, with the eventual goal of 500 767-size tankers. If Boeing remains at the same production level beyond the initial 100 aircraft, it will be 2030 before the final KC-135 is retired, by which time the youngest will be 65 years old.

Boeing's proposal is based on the 767-200, as selected by Italy and Japan. The configuration offered to the USAF is modelled on Italy's combi configuration, accommodating freight and passengers on the main deck, with lower lobe fuel tanks.

The KC-135R can lift a transfer fuel load of around 90,720kg (200,000lb), or 68,000kg over a 2,420km (1,300nm) range. The USAF has asked for an aircraft roughly in that class, but offering "a little better" payload/range performance, says an industry source. Boeing plans to equip the aircraft with further refinement of its fly-by-wire refuelling boom, along with the option of centreline and underwing hose drum units or an end- of-boom adaptor for probe-and-drogue refuelling.

It also plans to offer an improved version of its Remote Aerial Refueling Operation (RARO) system, developed for the Royal Netherlands Air Force's four KDC-10 tankers. RARO 2 will incorporate improved optical capability and, by having the boom operator positioned forward in the aircraft cabin, will avoid the need for structural and environmental system changes to accommodate the boom operator in the rear underside of the aircraft as on the KC-135 or KC-10.

The USAF is keen to promote system commonality between its next tanker and a proposed Multisensor Command & Control Aircraft, which is likely to be based on the larger, more modern 767-400 (Flight International 26 February - 4 March). Boeing is proposing to transfer the latter's two-man glass cockpit to the 767-200 tanker. The air force is also exploring the loosely defined concept of a "smart tanker" that could be equipped for communications relay or with passive sensors, and undertake some of the RC-135 Rivet Joint intelligence gathering missions.

Source: Flight International