An Eastern Airlines executive testified today that "apparently there is some confusion" among the airline's maintenance personnel as to who was responsible for ensuring proper installation of engine oil seals on its L1011 jumbo jets.

James Foucault, director of line maintenance for Eastern, made that statement in response to questioning at the National Transportation Safety Board's investigation into the failure of all three engines on an Eastern L1011 May 5.

The plane, carrying 172 people from Miami to Nassau, made an emergency landing in Miami after the crew restarted one stalled engine and avoided ditching in the Atlantic Ocean.

It was discovered that oil had leaked from all engines because the seals were missing on a bolt penetrating the oil system. That bolt is changed daily on each engine, and Eastern procedures require installation of new seals, called O-rings.

Two mechanics who worked on the airplane testified Monday that they never replaced the seals, that seals were attached to the bolts when the mechanics picked them up at a supervisor's station. Daniel R. Ormson, an Eastern technical foreman, testified today that he and his assistants never replaced the seals, that it was the mechanics' job.

The confusion helps explain 12 events on Eastern L1011s dating to September, 1981. Since that time, according to Federal Aviation Administration records introduced today, engines on the airline's L1011s have shut down in flight on six occasions. Four times the oil seals were missing; two times the seals were damaged.

Damaged seals caused major oil leaks on two other occasions, and in four instances the bolt was missing. The engines did not shut down on these six occasions, however.

FAA inspectors discussed each event with Eastern, but took no formal action until after the May 5 incident, when it initiated investigations against the two mechanics. They subsequently received 30-day suspensions.

On one day, Jan. 14, 1982, two L1011 engines were shut down because of missing seals. At that time the FAA threatened to impose its own maintenance system on Eastern mechanics if the problems did not stop, according to Samuel Anderson, the FAA's principal inspector for Eastern.

Between then and May 5 there were no more engine shutdowns traced to missing seals, but there were some damaged seal cases, Anderson said. The FAA took no disciplinary actions, because Eastern had either suspended or reprimanded mechanics, he said.

Safety board Chairman Jim Burnett asked Anderson if FAA inspectors had visited the maintenance line to view the process of changing bolts and seals.

"We made contact at the vice-president level," Anderson said.

"Vice presidents are not putting on O-rings," Burnett said.

The FAA traditionally has been reluctant to dictate specific maintenance procedures and is moving even more in that direction with a proposed program called Regulation by Objective, where each airline establishes its own procedures to meet FAA standards.

Anderson also told Burnett he had not learned until after May 5 of a change to the L1011 oil seal system that Pan American World Airways made on its L1011s after several of the bolts came out, as has happened four times at Eastern. A major concern of aviation safety specialists is that problems discovered and repaired by one airline are not transmitted by the FAA to other airlines.