The Federal Home Loan Bank Board gave final approval this week to a regulation liberalizing restrictions on real estate loans issued by federally chartered savings and loan associations.

The new rules, possible because of revision of banking laws passed earlier this year by Congress, removes all dollar limits on home loans and allows thrifts to make consumer loans, 40-year mortgages, home improvement and second-lien home loans.

Before the restrictions were lifted, federally chartered S&Ls were only allowed to make consumer loans for mobile homes, home improvement or educational purposes.

The removal of the first-lien restriction will give flexibility in high-cost areas to consumers who wish to purchase a two-to four-family dwelling. While approval of the 40-year mortgage conceivably could help first-time home buyers negotiate lower initial payments, it doesn't necessarily mean that lenders will be willing to finance a loan for 40 years at the same low rate.

The bank board heard some objection to the 40-year plan from those who argued that the initial decrease in monthly payments would be slight, while the total increase in interest payments over the longer term would be substantial.

The amendment also decreases the loan-to-value requirement for loans on multi-family housing units and commercial properties and removes restrictions on the geographical areas where federally chartered S&Ls are allowed to make loans. This will help buyers in areas where mortgage money is not readily available by attracting money from areas with money to lend.

The bank board also withdrew a proposal to liberalize requirements for private mortgage insurance on loans exceeding 90 percent of the value of the property, emphasizing the unwillingness of the FHLBB to encourage high-risk loans.