A survey of working air traffic controllers shows 58 percent opposed unconditionally to rehiring any of the 11,500 controllers fired last August, the Roper Organization reported yesterday.

Burns W. Roper, chairman of the national public opinion research firm, told Congress that comments from a large minority of the responding controllers surveyed during the last month suggested that the air traffic control system is safe now but "severely strained" because it is undermanned. He said the controllers reported that there is a limit to how long they can maintain the schedules and demands imposed on them.

Roper told Congress that a large minority, 31 percent of those polled, felt some controllers should be hired back under certain circumstances and that 10 percent said the fired controllers have "paid the price" for striking and should be rehired, no strings attached.

The findings were reported to the House Public Works and Transportation investigations subcommittee, which commissioned the survey. Questionnaires were sent to 897 controllers randomly selected from the 4,934 who stayed at work last August during the strike of the Professional Air Traffic Controllers Organization. Roper said that 731 controllers, "an almost unprecedented response" rate of nearly 82 percent, returned the questionnaires. Anonymity was assured, Roper said.

The 58 percent who wanted none of the controllers rehired suggested in written comments that the strikers were troublemakers and had broken their oaths. They also said they had been harassed by the strikers before the strike and would be harassed again if strikers were rehired. "A number mentioned that the strikers had engaged in practices that endangered the air control system and would do so again," Roper said.

Meanwhile, the Federal Aviation Administration confirmed rehiring three of the 11,500 controllers who were fired last August for not heeding President Reagan's order to return to work within 48 hours.

FAA spokesman Fred Farrar said that the three were among 1,000 "hardship" cases being reviewed and that others could be reinstated. Farrar and DOT officials said the rehirings did not represent a change in the general policy barring reinstatements, noting that the administration has said all along that it would review cases where controllers contended they were "harassed or intimidated" into joining the strike.

One of the three was Joan Plummer, a controller who worked at the Fort Worth Air Route Traffic Control Center before the strike and will join the Houston center now, Farrar said. "She was able to prove to the satisfaction of the FAA that she was harassed," he said.

Gary Eads, president of the decertified PATCO, said he had no role in the reinstatements. He said PATCO's figures show that about 45 percent of the fired controllers have found new work, and that another 15 to 20 percent would not return to the air control system even if offered reinstatement.