New stealth fighter plagued by overheating

The F/A-22 Raptor is outfitted with the most sophisticated components available, but as the Air Force's new stealth fighter enters operational testing this month, those advanced technologies could cause a serious glitch: overheating the jet as it idles on the runway.

Air Force acquisition chief Marvin Sambur said recent adjustments to the avionics software should mitigate the problem, which could be exacerbated by the summer weather at the Raptor's operational testing range at Edwards Air Force Base in southern California. Sambur said the Air Force also is examining a long-term plan that would modify the aircraft's hardware to increase cooling capacity in its fuel bays.

Still, other Pentagon officials say it is unclear whether the overheating will continue to plague the aircraft in warm climates, posing a risk to the fighter's sensitive avionics.

"It's an airplane that costs $300 million a copy, and you still have to park it in the shade," joked one Pentagon official who has expressed concerns about the problem.

Finding a shady spot to park the aircraft was one initial fix used to avoid overheating, according to Air Force Gen. Mark Welsh, director of global power programs, but other efforts included chilling the plane's fuel supply and scheduling flights during the cool, early morning hours.

Air Force officials say the problem is minor and infrequent. In flight, the F/A-22 is cooled by using airflow. But on the ground, the fighter's gadgets can sometimes generate too much heat during maintenance or air traffic delays in warm weather.

Internal liquid cooling systems are designed to keep the temperature of the F/A-22's high-tech systems at 68 degrees. But once the cooling system transfers heat to some of the plane's gas tanks, the fuel cannot stay cool for prolonged periods while parked on the hot tarmac.

Software solutions for such complications have been installed, and the problem is unlikely to thwart the Air Force's plan to complete operational testing and approve full-scale production of the $72 billion program in January.

The Air Force continues to explore a long-term solution to the problem, including using even more fuel tanks to absorb heat from the cooling system, reducing the amount of heat produced by the avionics, and additional air-cooling capacity with vents in the rear of the aircraft. The cost and feasibility of these options are currently under consideration.

"We're going to fly this airplane where it's hot, so we need to have it fixed," Welsh said.

The F/A-22 has strong support in the House, where rank-and-file members earlier this week sent letters to House Armed Services Chairman Duncan Hunter, R-Calif., and House Defense Appropriations Subcommittee Chairman Jerry Lewis, R-Calif., urging them to fully fund the president's $4.7 billion funding request for the plane in fiscal 2005.

Senate Armed Services member John McCain, R-Ariz., said in April he would consider canceling "this airplane that is going to cost between $250 million and $300 million dollars a copy."