More than 10,000 Washington area families who lived in certain federally subsidized housing projects may be eligible for refunds of up to$500 for illegal rent increases they paid four years ago.

The refunds are part of a $60 million settlement between the Housing and Urban Development Department and a legal services lawyer who filed a class action suit in 1975 on behalf of an estimated 500,000 tenants in 5,000 affected projects across the nation.

Ninety of the projects are in the Washington area, including Edgewood Terrace and Gibson Plaza in the District, Tysons Towers in Vienna, Rock Creek Terrace in Rockville and Capitol View in Landover.

Persons who lived in a so-called Section 236 project between Feb. 1, 1975, and Sept. 30, 1977, may be eligible for refunds but must file claims before next Jan. 31.

The Section 236 program was created by the 1968 Housing Act to provide apartments for families who earned too much to qualify for public housing but too little to be able to afford housing in the private market.

The projects were able to charge low rents because HUD subsidized their mortgages.

"It's been a long, long hard fight," said Patricia Tenoso, the California lawyer who filed suit. The settlement was the largest ever in a consumer class action case, Tenoso said.

"After a four-year struggle, up to a half-million people will finally get back the money they are owed," Tenoso said yesterday.

Tenoso and another legal aid attorney, Jamess Sturdevant, were in Washington yesterday as part of a nationwide tour to publicize the refunds and encourage tenants to file claims.

Tenoso filed the class action suit in U.S. District Court here after HUD refused to obey the law and pay for increased utility costs in the projects.

Since the department would not pay the bills, the project owners and managers increased rents to cover them.

In 1977, while Tenoso's suit was pending, Congress passed a second law, mandating HUD to make the payments for a special reserve fund.

"It's extraordinary for Congress to enact two laws to get HUD to do what (Congress) wants," Tenoso said.

Last year, former HUD secretary Patricia Roberts Harris ordered the department to settle the suit.

Under that settlement, which ws completed in September, five legal services lawyers who filed similar suits will oversee the refunds, and not the federal housing department.

"HUD said they couldn't do it, that it was an administrative nightmare, so we told them we'd do it," Tensos said.

The lawyers have invested the $60 million and the income that it generates will pay for processing the refunds and publicizing them. The lawyers have hired a private firm to handle the refunds and the J. Walter Thompson advertising firm to put together a $150,000 radio and TV campaign. t

HUD has sent claim forms to all the involved projects, but the lawyers estimate that as many as half of those eligible for a refund no longer live in the projects.

Former tenants can obtain a form from their old building or by calling toll free 800-824-7980.

Jerome, Smith, a 44-year-old cabdriver who was the only local tenant to file one of the suits four years ago, helped Tenoso hang a publicity poster in the Immaculate Conception Apartments, 1330 7th St. NW, yesterday.

"It was a long time in coming but it's great," said Smith, who filed suit after receiving a $40-a-month increase in 1975.

Persons who lived in the following projects between Feb. 1, 1975, and Sept. 30, 1977 may be eligible for refunds: DISTRICT

Azeeze Bates Court, Benning Road Apartments, Brentwood Village Apartments, Capitol Manor, Capitol Towers, Capitol View Plaza, Columbia Heights Village, E Street Apartments.

Eastern Avenue Apartments, Edgewood Terrace Apartments, Section II, Fairmont Square, Foster-House, 46th Street Apartments. Gibson Plaza, Glen Arms Apartments, Glendale Gardens Inc.

Golden Rule Apartments, Golden Rule Center, Hedin House, Immaculate Conception Community, Langston Land, Lincoln Apartments, Lincoln-Westmoreland, Mayfair Mansions, Park Road Apartments.

Parkway-Overlood East, Pentacle Apartments, S Street, Samuel Kelsey Garden Apartments, Sayles Place Homes. SCORD I, Valley Wind, Shaw Urban Renewal -- Parcel 15, Southern Avenue Inc.

Stoneridge I & Ii, Trenton Terrace, Twelfth, Street Apartments, Tyler House, Urban Village, Washington Apartments. ALEXANDRIA

Cameron Overlook, Landmark Apartments, Old Town West (Phase I), Pendleton Park Apartments. ARLINGTON Culpepper Gardens. FAIRFAX CITY Suburbia Fairfax Apartments. FAIRFAX COUNTY

Buckman Road Apartments, Chantilly Pines (Herndon Gardens), Elden Terrace, Fellowship House -- Section II, Land Ane, Fox Mill Apartments, Hybia Valley Apartments, Lakeview, Laurel Glade Apartments, Reflection Lake I, Tysons Towers, Wexford Manor Apartments Woodlawn Village, Section 2. MONTGOMERY COUNTY

Amity Gardens, Bauer Park Apartments, Emory Grove Court, Friendly Gardens, Georgian Court Apartments, Great Hope Homes.

Leafy House, Manor Town, Montrose House, Park Montgomery, Rebecca, Rock Creek Terrace, Stewartown Homes.

Suburban Park Village, Towne Center Apartments. The Willows. PRINCE GEORGE'S COUNTY

Arnold Gardens, Birchwood Garden, Capital Towers, Capitol View, Section I & Section II.

Crest Apartments, Eastern Avenue Apartments, Imperial Gardens, Kimberly Gardens, Section I, Laurelwood Mutual Home, Millwood Townhouse, Nalley Apartments, Park 16 Apartments, Quincy Village.