Rep. Claude Pepper (D-Fla.), chairman of the House Select Committee on Aging, called yesterday for a grand jury investigation of the conduct of the District of Columbia government in licensing homes for the elderly, and he denounced city fire officials as incompetent and unprofessional.

Pepper angrily told D.C. Fire Chief Jefferson W. Lewis' aides that the 10 elderly people who died in fires this month, in an unlicensed Lamont Street home for mental outpatients and at The Roosevelt for Senior Citizens, are "testimony" to the "bungling, red tape, administrative incompetence and confusion" in the city government. Nine of the 10 died at the Lamont Street home.

"That chief is a dumbbell," Pepper said to the committee's staff director during a recess in the daylong hearing.

As he left the Caucus Room of the Cannon Office Building, a shaken Chief Lewis told reporters, "My department has been unfairly attacked."

Battalion Chief Richard M. Hubscher, who serves as the department's official spokesman, said "Yes, I agree" to a radio reporter's suggestion that "you have egg on your face."

There was no suggestion during the two hours of grilling Lewis, Hubscher and Fire Marshal Lt. Jack Fletcher that the city's firefighters had failed to enforce any codes or properly fight the two fires.

What was at issue for most of the discussion was Pepper's contention that fire inspectors should have demanded that the proper city departments reclassify The Roosevelt from its status as a residential hotel to that of a senior citizen home.

At the scene of Tuesday's early morning fire at The Roosevelt, Hubscher said that smoke detectors "could have possibly saved the life" of Terrell H. Pick, 629 The fire broke out in Pick's one-room efficiency on the top floor of the building.

The 60-year-old Roosevelt, an eight-story brick building at 2101 6th St. NW, is classified for inspection purposes as a residential hotel. It has been a senior citizen's center for several years.

Pepper's anger grew out of repeated attempts to get Chief Lewis to say whose responsibility it was to see that the property was reclassified to account for its present use, an action that could have required the owners to install smoke detectors and a sprinkler system.

The three fire officials repeatedly replied, when they answered at all, that they did not know whose responsibility it was. Further, the chief said, fire department inspectors did not know the building was no longer a hotel.

"It says Roosevelt Senior Center printed right in front of the building on 16th Street," said Pepper, who went to the fire scene Tuesday.

Rep. Mario Biaggi (D-N.-Y.), a former New York City policeman, told the fire officials, "Gentlemen, I'm partial to the uniformed forces, but yours has been a dismal and unprofessional performance here today."

Lewis, 59, a 32-year veteran of the department, moved up to chief from deputy chief 13 months ago. His selection by then-mayor Walter E. Washington was criticized at the time by the D.C. Fire Fighters Association, which asserted that Lewis lacked the necessary administrative skills to run the 1,450-member department.

In the style of the Watergate hearings, Rep. Marc L. Marks (R-Pa.) demanded that the officials tell "how many meetings you had and who you met with" in preparing for the hearing.

Hubscher said he, Fletcher and the chief met together in the morning "but we were unkowledged about what your questions would be. We tried to surmise waht you would ask."

At a second meeting prior to the hearing, the fire officials talked to city communications director Alan Grip, "who gave us the city's outlook," Hubscher said.

"He told you what to say," Mark said.

"Guided us," corrected Hubscher.

Contacted after the hearing, Grip said he met with Lewis and his aides to "make sure" they were prepared for their appearance before the committee, especially because they had not been asked to present testimony and were not given questions in advance.

"I played Claude Pepper and presented hypothetical question," Grip said. The Barry administration, he added, "is not in the business of programming, or even guiding," its department heads.

Pepper called the hearing in the wake of recent fires in the District, Montgomery County, Connellsville, Pa., and Farmington, Mo., that killed a total of 45 elderly paitents and injured 30.

While the District was being criticized from all sides, Montgomery County officials were praised for the handling of a fire on April 13 at the University Nursing Home in Wheaton.

Gordon F. Vickery, the U.S. fire administrator, told the committee that "I have no doubt that as many as 20 people would have been killed had it not been for key safety factors." Two patient died after the Wheaton home was evacuated.

Vickery said that while federal investigators found "various violations" in similar fires in the District, and in Farmington, Mo., and Connellsville, Pa., "prompt and efficient tactics" by the Silver Spring Fire Department, coupled with efficient action of the home's trained staff," minimized the damage to life and property.

Lt. LeRoy R. Oettinger of the Silver Spring Fire Department testified that "the dramatic difference between the [Wheaton] fire and others you have heard of today can, in part, be attributed to safety standard imposed by the U.S., Maryland and Montgomery County regulations.

"We intend to press for federal minimum fire-safety standards for all group housing facilities which maintain individuals whose stay is paid for by the federal government through programs such as supplementary security income, veterans benefits, Medicare and Medicaid," Pepper said.

Rep. Marks said that 120 of the 360 or so residents of The Roosevelt receive federal assistance and that the owners purchased the building with the help of a loan from the Department of Housing and Urban Development. CAPTION: Picture 1, FIRE CHIEF JEFFERSON LEWIS . . . department "unfairly attacked"; Picture 2, D.C. Fire Chief Jefferson Lewis, right, and Lt. Jack Fletcher wait to testify before House committee. By James K. W. Atherton-The Washington Post