By Mark Alpert

(FORTUNE Magazine) – The top U.S. business schools are starting to focus on an inefficient management system that's uncomfortably close to home: the traditional tenure process for professors. Like their counterparts at other schools, B-school deans find it almost impossible to fire profs. Poor performance -- or even an obsolescent job -- are never sufficient grounds. Many deans are trying to modify this lifetime job system, but tenure is academia's most sacred cow. Says Charles Hickman, a director of the American Assembly of Collegiate Schools of Business: ''The problem has no clear solution, and it's getting harder. It will either make or break us.'' Harvard business school dean John McArthur is said to be particularly concerned; of his 214 faculty members, 91 have tenure. McArthur recently raised the tenure topic in a speech to the school's alumni. He told them that the problems posed by tenure will get worse after the elimination of mandatory retirement. A 1986 amendment to the age discrimination act banned firing for reason of age. But tenured professors were exempted and could be forced out once they reached 70. The exemption expires in 1993. He said the situation will require creative solutions but did not elaborate. He declined to be interviewed. John Rosenblum, dean of the University of Virginia's Darden school, says alternatives to tenure should be explored, such as five-year renewable contracts. Darden, along with most other top business schools, already offers short-term contracts to experienced business and public leaders who turn to teaching. Another proposal comes from Donald Jacobs, dean of Northwestern University's Kellogg school. He says he gets rid of bad profs by simply making them ''uncomfortable and unhappy'' as a result of his annual salary review and assignments. But that may not always work. Says Richard West, dean of New York University's Stern school: ''Unless they have other options, you can't make it bad enough for them to leave.'' West says the only systematic way to get rid of ineffective professors would be to institute a costly and controversial post-tenure review process -- something that universities are loath to consider because, he says, ''It would take a hell of a lot of time and ! energy.''