Team Proposes Plan to Fix C-17 Wing : Aircraft: McDonnell Douglas says costs to add metal reinforcement to the cargo jet would fall within reserves.

The Air Force’s independent team examining the test failure of the McDonnell Douglas C-17 cargo jet wings has recommended a fix-it plan that will add 600 to 700 pounds of metal reinforcement to the plane, a company official said.

The wing failed last year during a ground test to determine if it met Air Force standards requiring it to bear 150% of anticipated flight loads. It broke at 128%, well short of the goal.

Although the Air Force must formally approve the recommendation, Pentagon officials said it was unlikely they would challenge the independent team’s report. Sources said a key Air Force official has informally endorsed the McDonnell plan, one of several options under consideration.

Ken Francis, McDonnell executive vice president, said cost of the wing fix will easily fall within a $269-million reserve taken in 1992 to cover existing and future C-17 problems. Knowledgeable sources said the fix would cost about $50 million, putting it at the very low end of early estimates.

Francis said the wing broke because of a specific computational error by engineers, the effects of which were magnified by other assumptions about how flight loads would be distributed in the wing’s structure.

McDonnell also examined the entire C-17 aircraft to determine if similar mistakes had occurred elsewhere. As a result, other areas of the wing were beefed up, but the rest of the plane passed the review, Francis said.

“This is not a threatening redesign at all,” Francis said. “It was a very straightforward failure and a very straightforward fix.”

The fix to the wings will involve strengthening areas around access holes on existing wings and eventually producing a stronger redesigned wing, he said. The test aircraft that broke last year will be fixed and retested, starting in July, Francis said.

A member of the Air Force’s independent review team, speaking not for attribution, confirmed Francis’ assessment.

Engineers got “too close to the edge” in trying to minimize the wings’ weight--a key concern in any aircraft design and particularly the C-17. McDonnell separately plans to add 600 pounds to the trailing edge of the C-17’s flaps to redress cracking.

Not including the extra weight for the fixes, the C-17 weighs about 268,000 pounds empty of fuel or cargo, compared to the original goal of 245,000 pounds. The plane weighed 265,000 pounds in 1988. A McDonnell spokesman said the company is studying how to shave weight off the aircraft.