The International Brotherhood of Teamsters lost its bid to represent more than 7,000 fleet service workers at USAir Group Inc., handing the carrier a victory after a year-long bout with the union over its organizing drive.

It was the Teamsters' second attempt to organize the carrier's baggage and cargo workers, coming after the union successfully appealed the results of a January representation election, which the Teamsters also lost.

The latest vote is a double blow for the Teamsters -- not only did the union lose the right to bargain for additional workers, it lost the right to represent the approximately 4,000 workers it previously had represented at the carrier.

The union had represented USAir's fleet service workers before its merger with Piedmont Airlines in August 1989.

When the union sought to broaden its representation to include the newly acquired Piedmont workers, the National Mediation Board ordered an election in which USAir campaigned hard against Teamster representation.

Since the first loss for the Teamsters, USAir -- which generally enjoys some of the best labor relations in the airline industry -- had announced it was cutting approximately 3,600 jobs from its work force of 54,000 people.

The layoffs included approximately 2,100 fleet service, customer service and reservations workers.

Even so, fewer than 35 percent of the workers eligible to vote in the election cast ballots to be represented by the Teamsters.

Under the law governing labor relations in the airline industry, a majority of those eligible must vote in favor of representation for the union to be certified. Only 2,475 employees cast their ballots in favor of the Teamsters.

After the Teamsters lost the first election last January, the union charged that USAir had interfered with its organizing drive.

USAir denied any wrongdoing, but the mediation board found that the election results were "tainted" and cleared the way for a second election.

Until the mediation board certifies yesterday's results, the Teamsters will continue to represent the employees for whom it has bargained in the past.