At 6 o'clock on a Monday morning in 1983, Audrey McGowan was on her way to work. She was 72 years old, but healthy, energetic and alert. She stepped onto an escalator at the Metro Center subway station in downtown Washington. Abruptly, the escalator stopped, throwing her off balance.

McGowan fell most of the way down the malfunctioning escalator's 94-foot slope. She had a heart attack, a broken neck, a fractured wrist, shoulder injuries and, according to a medical report, severe brain damage. She was rushed, unconscious, to a hospital and has not regained her health.

The accident, which led to an $875,000 out-of-court settlement last month by the transit authority and Westinghouse Electric Corp., the escalator's manufacturer, has underscored a key safety issue: Escalators are the chief cause of accidents in the subway system.

Despite repeated attempts by Metro to eliminate hazards, more than 100 passengers are injured each year on escalators, frequently because of falls. In January, a 3-year-old girl was killed after a fall on an escalator when a drawstring on her jacket hood became caught in its treads. Her death was the first on a Metro escalator.

Escalators have caused 70 percent of the injuries sustained by riders since the rail system opened in 1976, according to Metro. The total far exceeds those stemming from train derailments, bumps from subway doors and other accidents on platforms. Transit officials say further measures are needed to ensure safety.

Accidents on escalators have led to investigations, debate and lawsuits against the transit authority, including a $30 million suit pending in U.S. District Court here by the family of the 3-year-old child. Other lawsuits have cited mangled limbs and back injuries along with minor cuts and bruises.

McGowan, now 74, remembers little about the accident that brought a sudden end to her 31-year career as a file clerk for the Navy. She recalls grasping a handrail as she started down the escalator on Sept. 26, 1983.

"I don't know what all happened," she said in a faltering voice in a recent telephone interview from her sister's home in Wexford, Pa., near Pittsburgh. "I woke up in the hospital. Everything happened too fast."

But her lawyer, Kenneth M. Trombly, said he has gathered evidence pointing to negligence by Metro and Westinghouse in the way the escalator had been run.

The escalator, which is at 12th and G streets NW, had repeatedly malfunctioned and should not have been in use that morning, according to Trombly.

A station attendant violated mandatory procedures by turning on the escalator without properly inspecting it or checking a log in which previous breakdowns were noted, Trombly claimed.

He added that Metro and Westinghouse failed to take adequate steps to repair the escalator and ensure safety.

The transit authority, which paid McGowan $850,000, one of the largest payments in an escalator accident here, has not disputed Trombly's key contentions. "We did not follow our own procedures," said Metro general counsel Sara E. Lister. "The procedures were in place. We just did not follow them."

A lawyer for Westinghouse acknowledged that the company has agreed to pay $25,000 to McGowan but declined to comment on the lawsuit.

What caused the escalator to malfunction has not been determined. A gummy, putty-like substance was later found on one of the handrails, and officials said this material may have led to the sudden stop. But Trombly has argued that the substance probably was placed on the rail after the accident.

Unexplained stops are a recurrent problem on Metro escalators. Since 1983, the subway system has reported nearly 1,000 abrupt shutdowns by escalators. Nearly 40 percent of those incidents remain unexplained. The others were attributed to mechanical failures, vandalism and automatic shutoffs by fail-safe mechanisms.

Only a small number of these inadvertent stops result in injuries, Metro officials say. Some occur when no one is on an escalator. In other instances, riders avoid injuries by grasping a railing. But, officials say, the stops may be hazardous for elderly, frail and other persons who do not hold on or who lose their grip.

John F. Nicholson, the attendant on duty when the 1983 accident occurred, has said in a sworn statement that he turned on the escalator and did not "remember examining" the station's log. He claimed no procedures were required before starting an escalator -- a point disputed by Metro officials and by Trombly.

"There was no fault of mine," Nicholson said in a brief telephone interview. "I didn't turn it on when I wasn't supposed to." He refused to elaborate.

According to Metro officials, Nicholson, now 70, retired in May after eight months' medical leave. He had been a station attendant since 1976. No disciplinary action was taken after the 1983 accident, officials said, because Metro could not immmediately establish who turned on the escalator.

Since 1983, the transit system has taken several steps to improve safety on its 436 escalators, including providing more training for attendants at the 57 stations and tightening procedures for reporting breakdowns. Malfunctioning escalators now are inspected and repaired on weekends as well as on weekdays, officials said.

On the Saturday before the 1983 accident, the escalator had been taken out of service after stopping abruptly three times. Because of a lack of repair service on weekends, the escalator had not been inspected or fixed before the station opened on Monday. McGowan was the first person to use it that day.

As a safety measure in 1983, Metro reduced the speed at which escalators move from 120 feet per minute to 90 feet. However, the escalator on which McGowan was injured had been adjusted to the slower speed before the accident, officials said.

These and other moves have led to a marked decrease in accidents, transit officials say. The number of injuries caused by escalators dropped from more than 180 a year in the early 1980s to 158 last year and 102 during the first nine months of this year.

The decrease is significant, Metro officials say, because ridership has risen sharply during that period as the rail system expanded. "The rate of passenger injuries on escalators has decreased from 7.71 per million passengers in 1976 to 1.70 per million passengers in 1984, an improvement of 77.9 percent," the agency said in a safety report.

Westinghouse has recently designed a device aimed at bringing escalators to a more gradual stop. A company spokesman said tests of the equipment, known as a controlled stop brake, will begin shortly. Metro officials say they plan to install the devices as soon as possible to reduce the hazards of sudden stops.

"When that's put in, we're going to reduce this dramatically," said David O. Cooksey, Metro's general maintenance director. "We have matured a lot in how we do business. We learn, unfortunately, from some of the accidents we've had."

On the day of her accident, McGowan was on her way to the Navy Annex on Columbia Pike west of the Pentagon, where she worked as a mail room clerk for the Navy's personnel branch. She had been a quiet, level-headed employe who rarely took a day off and often arrived early, her friends say.

"Really, for 72, I thought she was fairly sharp," said Robert Skelley, her supervisor at the mail room. "She was pretty active herself. She never missed work. She had close to 3,000 hours' sick leave that she had accumulated."

After the accident, she remained unconscious for nearly three weeks at George Washington University Hospital. In all, she spent four months in the hospital undergoing medical treatment at a cost of $200,000. Her brain injuries have led to some loss of memory, nervousness and tremors in her right hand and in her head, her friends say.

"She has to have someone to care for her," said her sister. "She can't turn her head; she has to turn her whole body . . . . It's painful, extremely painful."

She cannot bathe or dress herself, her sister said. She has difficulty breathing. "She was always someone who wrote beautifully," her sister added. Now, she said, "she can't write a letter.

"She was a well person when she went down that escalator," her sister recalled. "The worst thing is she suffers from double vision." The blurred eyesight makes it difficult for her to read or watch television. "I believe it comes from the blow on her head."