Battalion Chief Hugh Clarke had just moved onto the second story of the burning rowhouse when the floor gave way.

"I tried to catch hold of something, and when I realized I couldn't, I figured the best thing to do was to relax and see what happens," Clarke recalled in an interview last week.

"In other tight situations over the years I had always come out smelling like a rose," he said.

This time Clarke landed head first on a sink, then toppled onto his oxygen tank, breaking his back.

Clarke spent six weeks in a hospital and six more months recuperating before he returned to full duty last fall. "I feel this is a worthwhile thing to be doing. I like my job, and that's why I came back," Clarke said in the same matter-of-fact tones as those with which he recalled his accident.

Clarke, 49, is among a number of Washington's firefighters and police officers who apparently could have retired with a tax-free disability pension but chose instead to return to work.

Now, amid publicity about recent disability retirements of top police and fire officials and with Congress scrutinizing the city's pension system, many of the men who have returned to the force are wondering what will happen to their benefits.

"It makes you wonder . . ." said firefighter John Stelmack, 40, who recuperated for six months from burns incurred over much of his body when he was trapped in a basement fire. "You wonder whether all the publicity about a few guys going out is gonna ruin it for guys when they're really injured," he said.

"It takes a lot of nerve to run into a burning building," said firefighter James Short, 31, who suffered a broken neck when part of a building fell on him two years ago. "I'll do it again, but you like to know if you wind up really disabled (that) you kids will be taken care of," he said.

"The stories (about the disability retirement system and the contentious claims of top officials) hurt every policeman," said one officer, who was shot twice in the chest, and by exercising rigorously, was able to return to work in seven weeks.

"People look at you now and say, "Oh, you're a policeman, one of those people who is going to take disability pay." The fact is, I never even thought about a disability retirement. I came back because I wanted to be a policeman. That's why I took the job, not because I was looking for a free ride. I don't think any real policeman is," he said.

Newspaper articles about the disability retirements of Police Chief Maurice J. Cullinane injured (knee), Fire Chief Burton W. Johnson (injured back) and Assistance Police Chief Tilmon B. O'Bryant (hypertension) have drawn new attention recently to the entire disability system.

Sen. Thomas F. Eagleton (D-Mo.) whose subcommittee is among those studying the system, has decried publicly what he termed abuses in a system where more than 80 percent of all policemen and firemen retire on disability. Eagleton, Rep. Romano L. Mazzoli (D-Ky.) and Sen. Charles Mc. Mathias (R-Md.) have promised reform.

Local police organizations have joined the criticism, charging that preferential treatment is given to high-ranking officials at the expense of rank-and-file members who must wait indefinitely for their disability claims to be processed.

Other members of Congress are speaking out, increasing the pressure to make changes. "In good conscience, how can I or other senators who are watchful of their constituents' limited pocketbooks, vote for continued appropriations for the District while abuses like this are allowed to continue?" Sen. John H. Chafee (R-R.I.) wrote Eagleton this week.

Proposed congressional changes would limit the amount of money awarded for a relatively minor injury but would not effect disability retirement benefits for police officers and firefighters who are 100 percent disable, according to Leslie Edwards of Eagleton's staff.

The number of police officers and firefighters who have suffered disabling injuries and returned to work is hard to estimate, partly because many of them refuse to discuss it. Most seem to know, or have heard about, at least one or two persons like themselves.

Several police officers have been shot and have returned to duty. One officer lost an arm during a hunting accident but insisted on coming back and was made a dispatcher. Officers with more serious injuries have wept upon being told they would have to retire.

One fireman broke his back when a ladder fell on him; one ruptured discs while pulling people onto a ladder from a burning building, and another suffered a broken neck when he tried to break the fall of a person jumping to escape a fire. All returned to duty.

Battalion Chief Clarke now inspects Metro installations. Recently he ran into a member of the Police and Firemen's Retirement and Relief Board who asked when Clarke would be coming before the board to seek a disability pension. That board member, Clarke said, "was shocked when I said I was back on duty. Usually, when you break a back, you're finished."

Firefighter Stelmack, whose burn scars turn blue and begain to ache after 15 minutes in the cold, nevertheless is on duty again."They tried to put me on a desk job, but I'm not cut out for that," he said."