Three years after Air Florida Flight 90 struck the 14th Street Bridge and plunged into the Potomac River, killing 78 persons and unleashing a wave of sorrow, sympathy and blame, the legal aftermath of the mishap has dwindled to a single, unresolved lawsuit still pending in U.S. District Court here.

The sole remaining case was filed last year by Air Florida stewardess Kelly Duncan, one of five survivors of the crash on Jan. 13, 1982, and the only crew member rescued from the icy waters.

Duncan, 26, now married to a Florida tennis pro, has been unable to work because of the psychological trauma associated with the crash, including guilt feelings about having survived it, according to her lawyer, Jeffrey A. Tew of Miami.

Duncan tried to work again with Air Florida a few months after the incident, but she found that she was too afraid of flying, a psychiatrist who examined Duncan said in court papers. The doctor said Duncan wept uncontrollably on one aborted flight after an engine caught fire.

Duncan, who lives in Miami, is unwilling to be interviewed, her lawyer said.

Tew said he is preparing a proposed settlement that will be submitted within 30 to 60 days to the defendants in Duncan's lawsuit. They are American Airlines, whose personnel de-iced the plane before takeoff from National Airport, the Boeing Co., maker of the plane, and the United States government, which owns National Airport.

By law, Duncan could not sue her employer, Air Florida. The airline has since filed for reorganization under the Bankruptcy Act.

Of the 87 lawsuits filed after the crash, few went to trial. Virtually all were settled in pretrial conferences here presided over by U.S. District Judge Joyce Hens Green. Of those tried in court, two are on appeal in Texas and Florida, according to a New York law firm representing the airline.

A bid by the District of Columbia to recover from Air Florida the costs of emergency services provided immediately after the crash and the cleanup and repair of the bridge was denied recently by the U.S. Court of Appeals.

All of the individual plaintiffs received some compensation, according to Donald W. Madole, a Washington lawyer appointed by Green to represent the relatives of crash victims. Madole will not say how much money was paid, although the total has been estimated at well over $50 million.

"There's no question that there were many, many seven-figure settlements," Madole said. "A lot of them."