Fleetwood Enterprises Inc., the nation's largest maker of mobile homes, built about 20,000 homes that fail to meet federal safety and construction standards, the government charged in a lawsuit filed against the company last week.

The suit, filed in U.S. District Court in Wilmington, seeks a $1,000 fine for each alleged violation of standards in the homes manufactured by Fleetwood plants in nine states, including Virginia.

In addition to the nearly 20,000 homes cited in the lawsuit, other models built as early as 1976 may not conform to federal regulations established by the Department of Housing and Urban Development, according to the department.

Because of the large number of homes involved, the penalties could add up to millions of dollars if the government wins the lawsuit.

According to the lawsuit, support walls and straps designed to hold down roofs in the mobile homes are faulty, putting the structures in danger of damage from leaky roofs, high winds, cracking of interior walls and separation between walls and the roof.

HUD establishes and administers construction and safety standards for the mobile homes under the National Manufactured Housing Construction and Safety Standards Act of 1974. The lawsuit caps four years of federal efforts to compel the manufacturer to meet the federal standards the government alleges were violated by Fleetwood.

Fleetwood contends that the differences between HUD and the company involve conflicting interpretations of engineering standards and that the company has had "no significant consumer complaints" about homes manufactured during the period covered by the suit.

The lawsuit charged that structures called "shearwalls," which are supposed to transfer wind-produced forces onto ceilings, floors and chassis, were not designed or built using "engineering analysis or tests which simulate actual loads."

At least one shearwall in more than half of the homes covered by the suit is incapable of sustaining "design loads established by federal manufactured home construction and safety standards" and at least one fastener between a shearwall and the floor system in these homes will be "overstressed" under loads specified in the federal standards, the suit alleged.

In addition, the government said, design flaws between floors and the chassis could lead to "wind overturning and sliding" the mobile home when it is subjected to design loads specified in the federal standards.

In other homes covered by the lawsuit, "uplift straps and fasteners" are not strong enough to withstand federal load requirements, according to the suit.

"An unknown number of additional homes constructed by Fleetwood" contain the same violations of standards as the nearly 20,000 specified in the lawsuit, the suit charged.

The Justice Department, which filed the suit for HUD, asked the court to order Fleetwood to identify other houses built under the design HUD believes is faulty, Assistant U.S. Attorney Richard C. Stearns said.

A Fleetwood official said the company is "pleased that we are finally going to get a chance to tell our side of the story" in court.

David R. Marriner, the company's treasurer and spokesman, said the manufacturer expects to defend its "interpretations" of the engineering standards and win the case.

The suit is not the first court action to grow out of the dispute between HUD and the manufacturer.

Fleetwood sued HUD nearly two years ago after the department scheduled a hearing on alleged violations in another 4,000 homes made by the company. The manufacturer argued that HUD did not have authority to schedule formal, open hearings if the company objected, and filed the lawsuit in an effort to block the hearings.

HUD held the hearings. Afterward, a New Orleans federal appeals court last year ordered Fleetwood to notify the owners of the 4,000 dwellings that their homes do not meet federal standards.

The company eventually won a lower court order requiring HUD to accept more evidence in the administrative proceedings in the case. The case is now before the New Orleans court again, as a result of a HUD appeal.