WASHINGTON (AP) _ Defense Secretary Les Aspin fired an Air Force general Friday for mismanagement in the C-17 cargo plane program, insisting there must be ''accountability at all levels'' of the Pentagon's multi-billion dollar weapons programs.

Aspin also disciplined two other generals and a civilian in connection with the aircraft, which has been plagued by $1.5 billion in overruns and wings that failed stress tests.

Aspin directed that Maj. Gen. Michael M. Butchko Jr., be relieved as commander of the Air Force Development Test Center in Florida ''based on his performance when he was the C-17 system program director,'' the Pentagon said in a statement.

''Gen. Butchko was the person in charge as program director and bears the chief responsibility,'' Aspin said of the two-star general.

In a memo to the acting secretary of the Air Force, Aspin cited ''the need for accountability at all levels.''

''If the system is to work, then those charged with the responsibility for the management of billion-dollar systems must perform to the highest standard,'' he said.

Butchko said he would retire a year early, effective June 1, and added, ''I walk away with full integrity.''

He denied any wrongdoing and said, ''When you sign up to be program director, if accolades arrive you catch them; if spears arrive, you try to dodge them, but you catch them. That comes with the territory.''

Aspin's action came in response to a January report by Pentagon deputy inspector general Derek Vander Schaaf that recommended disciplinary action against several Air Force officials, whom he did not identify, in connection with the program.

Vander Schaaf's report raised questions about the management and the financial integrity of the program, specifically about the Air Force officials' actions to provide financial assistance to the aircraft's producer in late 1990.

Critics in Congress have charged that the Air Force funneled some $450 million in program payments to McDonnell Douglas at a time when the company was in severe financial distress. The lawmakers have contended the payments were premature, improper and possibly illegal.

McDonnell officials said Friday the C-17's problems are in the past and assured stockholders the program will turn a profit this year.

''The airplane is doing extremely well in the flight test program,'' company chairman and chief executive John F. McDonnell told the company's annual stockholders' meeting in St. Louis.

The Army says it needs the aircraft to replace some of the military's aging transports, such as the C-141 and C-5. The new plane is supposed to have greater cargo capacity and the ability to land on short runways.

But some in Congress have called for suspending production.

Rep. John Conyers, D-Mich., chairman of the House Government Operations subcommittee on legislation and national security, applauded Aspin's decision as sending a message to stop ''business as usual'' practices in Pentagon acquisition.

Conyers has investigated the C-17 program and held several hearings on the issue.

''During the last year of our investigation, Defense Department and Air Force officials repeatedly assured us that they had done nothing wrong, but these assurances proved unfounded,'' Conyers said in a statement.

Butchko is in charge of the Air Force's weapons testing center at Eglin Air Force Base in Florida.

Aspin also directed that three men no longer work in the acquisition of weaponry for the Pentagon. They are:

-Lt. Gen. Edward Barry, Jr., formerly the C-17 program executive officer, now commander of the Space and Missile Systems Center.

-Brig. Gen. John Nauseef, the deputy chief of staff, financial management and comptroller at the headquarters of the Air Force Material Command.

-A. Allen Hixenbaugh, former C-17 program deputy director for contracting and now special assistant to the director of contracting, Aeronautical Systems Center, Air Force Material Command.

The actions taken against all the generals are severe enough to spell the end of their careers in the military. Oftentimes, officers of that rank retire if they are so disciplined. And since their specialties are in acquisition, it is unlikely they could switch to other job areas.

Aspin has placed both the management of the C-17 program and its financial operations under a longer-term review.

''The Air Force found that some management actions, while questionable, were within the range of normal management discretion. I disagree with this judgment,'' Aspin's statement said.

The Air Force originally planned to buy 210 of the transport planes, which are supposed to be able to carry large cargo loads over long distances without refueling. In April 1990, Defense Secretary Dick Cheney reduced the purchase to 120 aircraft.