Federal judges surveyed across the country report that about 9 percent of the lawyers appearing before them performed inadequately. Far short of the highly publicized charge by Chief Justice Warren E. Burger that between one-third and one-half of all trial lawyers are unqualified.

Forty-one percent of 366 federal judges felt that inadequate legal representation was "a serious problem" in their courts, according to the survey released yesterday by the Federal Judicial Center, created by Congress 10 years ago to streamline the work of the federal courts.

This new study is almost certain to fire up the feud between Burger and lawyers across the country who are unhappy with his cahrges against their trial ability.

Burger, however, has made it clear in speeches and private conversations that he is less concerned with the numbers game - whether 10 percent or 50 percent of lawyers taking cases to court are unqualified - than with developing a system to improve the ability of the nation's lawyers to handle trials.

"Any problem in the courts which 39 percent the final survey figure came to 41 percent of the judges characterize as serious demands our attention, no matter how many or how few of these advocates merit the label of incompetent," he told the American Bar Associatin in February.

One reason for the difference between Burger's estimate - based, he said, on conversations with trial judges - and the study findings is that the chief justice was referring to lawyers in state and local as well as federal courts while the Federal Judicial Center surveyed only federal court judges. Lawyers practicing in the federal courts are generally considered to be of higher quality than those practicing in state or local courts.

A survey of Maryland judges, however, found that 10 percent - about the same as the 8.6 percent reported by the federal judges - of the lawyers practicing in that state's courts were "habitual or chronic incompetents."

In the federal court study, the judges thought the major consequence of the inadequate performance by lawyers was "failure to fully protect the interest of their clients."

The judges, as well as a special sample of experienced trial lawyers, blamed the inadequate performances on a lack of trial skills and on poor preparation. Some lawyers don't even know how to conduct a proper crossexamination of a witness, the survey found, while others lacked the "skill and judgement" to develop an overall strategy for a case.

Experience seemed to be a key element in handing a trial well. The survey found more inadequate performances among lawyers under 30 and those practicing on their own than in older lawyers and those working for large firms which offer more backup help to the trial attorney.

Moreover, the survey found that the best rated lawyers had graduated from a list of nine of the nation's most prestigious law schools. None of the graduates from those schools was rated inadequate, while 10 percent of those from other law schools had inadequate performances reported.

Some judges used far stiffer criteria than others in evaluating the lawyers in their courts, and those were the judges who felt the inadequate performances by lawyers was a serious problem in their courts. If their criteria had been applied across the board, the study estimated that 13 percent of the lawyers' performances would have been called inadequate.

U.S. District Court judges in Washington were more concerned than their colleagues across the country about the problem. And federal appeals court judges found fewer inadequate performances than the trial judges did.