Five Washington and Baltimore area residents ranging from a smartly dressed hotel office manager to a retired cowboy were placed on probation in federal court here today after pleading guilty to cashing checks in a phony flood insurance reimbursement scheme centered in Bethesda.

The five, part of a group of 16 persons indicted last year on government fraud charges, acknowledged before U.S. District Court Judge Herbert F. Murray that they cashed checks from $2,400 to $4,000 each for the ringleaders in the scheme and kept a small portion for themselves.

Each had pleaded guilty to a misdemeanor charge of making a false demand against the United States.

The FBI estimated that the checks totaled $34,000 over a four-month period last year.

Murray imposed probation on the five defendants today ranging from 18 months to three years each and ordered most to make restitution to the federally run flood insurance program.

The 16, many of whom knew each other socially or professionally, were originally charged in a complex indictment alleging that at least three of the group solicited the others to cash phony reimbursement checks generated by the National Flood Insurance Program in Bethesda.

According to the FBI, Harold Stoner Bynaker, 40, a horse farm operator in Clarksburg, conspired with an employe of Electronic Data Systems, the private firm that processed National Flood Insurance Program checks, to "manipulate the firm's computer" to issue checks in the names of persons furnished by Bynaker.

Bynaker, his nephew, Ira Bynaker of Frederick, Wayne H. Carter of Boyds, and possibly others solicited friends and acquaintances to allow their names and addresses to be used for the phony flood insurance checks, according to prosecutors and the FBI.

Barbara Fourcade, an employe of Electronic Data Systems, then generated checks for those names, the FBI said.

Those persons next cashed the checks, giving most of the money to the Bynakers or others and keeping $100 to $800 of each check for themselves, according to prosecutors.

The FBI was tipped to possible irregularities and began checking records with Electronic Data Systems officials, the FBI said.

"A review of computer information disclosed that numerous fraudulent checks had been issued and that sophisticated entries had been placed into the computer in order to obtain the illegal funds and avoid detection," the FBI said.

Fourcade cooperated with law enforcement authorities, the FBI said, and the indictments followed.

Those sentenced today included Radie Evans, of Potomac, an elderly man who described himself as a former cowboy, and Barbara Egger, of Alexandria, a hotel office manager. Also sentenced were Charles J. Wenner, a carpenter, of Damascus; Clarence Koontz, 69, a retired truck salesman, of Frederick, and Randolph Whitby, an auto dealer and Vietnam veteran, of Frederick.

"Most of you people, other than what I would call the ringleaders, are basically good people," Judge Murray said to Whitby. "You were under economic stress at the time of cashing the check . . . and apparently yielded to temptation."

Of those remaining, four were sentenced earlier, one is a fugitive and the rest--including the Bynakers and Carter--are awaiting trial or have pleaded guilty and await sentencing.