A federal grand jury charged yesterday that an Arlington businessman made illegal car payments in 1977 on behalf of a Senate aide in an attempt to influence the government's purchases of soap products.

The indictment, returned in U.S. District Court in Alexandria, alleged John F. Bowles, former head of National Cleansing Products Corp., made five leasing payments of $312 each for a 1977 Cadillac driven by then-Senate aide Francis J. Brizzi Sr.

In return, the jury said, Brizzi -- a stockholder in Bowles' firm and staff director of the Senate Committee on Veterans Affairs -- was expected to help win General Services Administration approval of the company's products.

Bowles' lawyer, William B. Cummings, branded the indictment a "desperate, 11th-hour case. He's totally innocent. It's a far-reaching harassment attempt on the part of the government."

The grand jury charged Bowles' alleged payments to the car-leasing firm, Allstate Leasing Inc., occurred between February and June 1977. Cummings and a Senate official said yesterday Brizzi left the Senate payroll on Feb. 15 of that year. Four of the five payments in question were made after Brizzi was no longer a Senate employe, Cummings said.

Assistant U.S. Attorney Joseph J. Aronica said yesterday the now-defunct company's products were placed on a list of GSA-approved items, but "not personally" because of intervention by Brizzi.