Consumers would have an easier time evaluating the financial condition of savings and loans, but sick S&Ls still would be able to use controversial bookkeeping techniques to meet regulatory standards, according to new federal rules proposed this week.

The Federal Home Loan Bank Board, which regulates thrift institutions, proposed requiring the nation's 3,200 S&Ls to publish financial statements two ways: using generally accepted accounting principles and using more lenient regulatory accounting rules.

Today only the 250 thrifts that are publicly traded must report both ways, making it hard for depositors to assess the true health of most S&Ls without performing tricky arithmetic.

As part of the rule change, bank board Chairman Edwin J. Gray and the two other board members also proposed that S&Ls double their net worth -- the difference between assets and liabilities -- to 6 percent of assets during six years. The higher percentage would strengthen the balance sheets of healthy thrifts.

But the proposed rule would continue to permit ailing S&Ls to meet net worth rules by using controversial regulatory accounting.

Regulatory accounting principles are much more liberal than principles used by the Securities and Exchange Commission and by most companies.

Regulatory accounting rules have been created since the early 1980s by the bank board to let sick thrifts meet federal standards and stay open. Criticism of the novel bookkeeping techniques has grown recently. The General Accounting Office and several former regulators have said such methods can mask and prolong a thrift's problem.

Under existing rules, all federally insured thrifts must file a quarterly financial statement with the bank board using regulatory accounting rules. Only those thrifts that are traded on stock exchanges -- a small portion of the nation's total -- also must state results under general accounting principles.

The bulk of the nation's S&Ls, which must publish their quarterly results in newspapers or in leaflets handed over the counter, use only regulatory rules.

The difference between the two accounting methods can be stark.

At the end of 1985, for example, National Permanent Bank, the District's second-largest thrift, posted net worth of $1,000 using accounting rules used by thrift regulators.

Though not great, the slim results look far better than the $80 million loss the ailing savings institution would have posted under generally accepted rules. National Permanent has plenty of company.

The General Accounting Office calculates that, for the first half of 1985, only 88 S&Ls appeared to be insolvent, meaning they had a net worth of zero or less. The number would have risen to 461 if generally accepted principles had been used, the GAO said.

If the bank board's new proposals are adopted, such differences will be more apparent to more customers.

Noel Fahey, a spokesman for the U.S. League of Savings Institutions, a powerful industry lobby, said the league has not yet had time to study the proposals. "But I personally don't see what good this will do," he said.

Regulatory accounting allows S&Ls to count as assets many items that would not be permitted under generally accepted rules.

Among the items are bank board certificates that S&Ls have used to boost assets and, therefore, net worth by a total of $2.5 billion. Those certificates, which critics say amount to worthless paper promises, would not be affected by the rules proposed Thursday.

But the proposed rules would phase out several less controversial regulatory accounting techniques, including the practice of counting as assets funds intended to cover loan losses.

With interest rates falling and criticism of the techniques rising, Gray has said it is time to move S&Ls back to mainstream accounting. The bank board will accept comments for 60 days before taking a final vote on the proposals.