IN AN ACTION unprecedented in the airline industry, a federal grand jury has indicted Eastern Airlines and a number of its top maintenance managers on charges of conspiring to falsify safety maintenance records. The bulk of the 60 counts involves practices said to have occurred before a strike at Eastern that began on March 4, 1989, and before a team of new managers took over the carrier. Prosecutors emphasize that they have no evidence of improprieties at the airline since it came under the trusteeship of Martin Shugrue, who was appointed by a federal bankruptcy judge. Nevertheless, the charges raise highly disturbing questions about the airline's practice during a period of unusually poisonous labor-management relations.

According to U.S. Attorney Andrew J. Maloney, the indictment "is about failure to maintain aircraft -- both regular maintenance and parts that are faulty. The motivation was to get airplanes into the air. An airline only makes money with planes in the air." Mr. Maloney says a 10-month investigation revealed a pattern: top airline managers ordered that maintenance not be performed on aircraft but that records be made to show that it had. All the more chilling is the allegation in the indictment that by tampering with log books, work cards and computerized maintenance records, Eastern "did cause aircraft that were not properly maintained or repaired to fly and carry unsuspecting passengers."

Federal oversight of airline maintenance procedures in general has received increasing attention in recent years and has been more aggressive. As with airport security, there are no foolproof guarantees. Supervision of aircraft inspections cannot involve an on-site, over-the-shoulder check of every maintenance move; it requires an assumption of trust at the same time that it demands extraordinary regulatory scrutiny. In the case of an airline suffering bitter labor-management relations, efforts to ensure that the right maintenance is done become especially delicate.

On the whole, safety records of the airlines have been improving, even in the face of growing numbers of travelers and airplanes in the skies. The question that arises from the Eastern episode is whether maintenance by the carriers as well as surveillance by the regulators is close enough.