Only nine months have passed since Congress authorized a $10.8 billion shot in the arm for the ailing savings and loan industry. Even so, this nation's lawmakers need to ride to the rescue of the same industry again - and they had better not drag their feet in doing so.

That, in essence, is the recommendation this week from Congress' own auditing arm, the General Accounting Office. But it really should not take considerable prodding from the GAO to bestir Congress again; the unadorned facts and figures of the situation tell a clear story with an unmistakably plain moral.The basic fact is that the Federal Savings and Loan Insurance Corp., the fund that insures deposits in the nation's 3,120 savings institutions, is hemorrhaging badly. By the end of 1987, the liabilities of the FSLIC exceeded its assets by $13.7 billion - double the deficit of $6.3 billion a year earlier. All projections point to even more red ink in the future.

The persistence of the problem makes the White House look like it had better judgment on this matter than Congress. The administration wanted $15 billion a year ago to rescue the FSLIC, but Congress came through with only $10.8 billion through the sale of bonds over three years.

Though the problem arises mainly because the S&L industry has been hit hard by the collapse of oil and real estate markets in the Southwest, the rest of the country can't ignore it without inviting serious trouble all over the nation.

How serious? Well, if healthy S&Ls must increase their payments to the FSLIC to help overcome the deficits, many are bound to resent being forced to pay for others' mistakes and can be expected to leave the FSLIC to avoid the higher costs. Guess what that would do to public confidence in and patronage of the savings and loan industry.

Ordinarily, federal bailouts should be avoided. But the country simply cannot afford to let the $900 billion savings and loan industry collapse in a crisis of confidence. This is one case where withholding federal help would incur worse problems than providing it. Let's get on with the job.