In recent days, a Portland television station has aired two reports about the business practices of a wealthy congressional aide so prominent back home that he is sometimes called "Oregon's third senator."

KATU-TV reported that Gerald W. Frank, longtime administrative assistant to Sen. Mark O. Hatfield (R-Ore.), was for 25 years a director of an Oregon savings and loan that later collapsed at a cost to taxpayers of $113 million.

Reporter Mark Hass also disclosed that Frank's official travel in the last four years included 52 visits to New York, where he publishes an annual New York City travel guide that has earned him more than $1 million in the last six years.

Although the reports surfaced in the context of Hatfield's reelection campaign and one was distributed by the Associated Press, they were not covered by the Oregonian, the state's largest newspaper, which pays Frank $22,000 a year to write a weekly column.

Frank, 67, who has been a Hatfield aide for 23 years and is paid $85,000 a year, called the allegations "crap politically inspired by our opponent," Democrat Harry Lonsdale.

Frank, a millionaire whose family founded the Northwest's largest department store chain, said in a telephone interview from Salem that "I don't need to do this job. I do it as a public service. I am a personality in my own right. . . . I am a fourth-generation Oregonian. I have a credibility second to none in this state."

Frank said his "Friday Surprise" column poses no conflict because he does not write about politics and never mentions Hatfield's name. Two recent columns were about the Persian Gulf crisis, and a third, which mentioned his New York guidebook, was about that city's "brighter side," although he acknowledged it is "consumed by fear."

Oregonian Editor William Hilliard said he challenged anyone "to show where the public makes any connection between Gerry Frank and his column in the Oregonian, and Gerry Frank and Mark Hatfield." He said the column in no way "gives readers the impression that the Oregonian is favoring Mark Hatfield," although "the perception can be other than what is real."

Hilliard said the paper would look into the allegations about Frank's travel expenses and, "if we find out there's something there, we're going to report it."

Managing Editor Peter Thompson said the Portland paper was first to report Frank's service at American Federal Savings and Loan last year, when it broke the story that Rep. Denny Smith (R-Ore.) was a director at the same thrift. "We don't react to every single thing that's on local television," he said.

In the article last December, Frank's involvement is mentioned on Page G6 in the 45th and 46th paragraphs of a story that started on Page G1.

Frank, who was paid $4,800 a year at the S&L in Salem, remains a paid director of another bank and an insurance company and serves as a retail consultant. He said he had been "critical of the management" at American Federal and resigned in 1987, shortly before the collapse, because he was "disgusted" with its practices.

Under Senate rules, Frank is permitted to remain on corporate boards that he joined before becoming a Senate employee. He said he never discusses his business activities with Hatfield.

In an unusual arrangement, Frank lives in Oregon and commutes to Washington about twice a month. He has received $49,000 in travel reimbursements in the last six years, including 52 side trips to New York and 26 to Los Angeles that typically lasted two or three days, according to KATU's review of Senate records.

Frank said he does some Senate business in New York, although he also works on updating his guidebook, "Where to Find It, Buy It, Eat It in New York." He said that he pays for his daily expenses there but that it is often cheaper for the taxpayers if he flies back to Oregon from New York or through Los Angeles.

"I will admit to you there is the appearance of an oddity, but it's done within the rules of the Senate," said Bill Calder, a spokesman for Hatfield.

Frank added that any criticism is unfounded because he worked without pay for his first six years on Hatfield's staff and devotes substantial time to such civic organizations as UNICEF and the Boy Scouts.

Lonsdale has criticized Frank's S&L connection and the Oregonian's coverage. "Every time Mark Hatfield burps, it's on the front page of the Oregonian," he told KATU. "When we announced our campaign back in March, we were on the obituary page."

Mike Devlin, the station's managing editor, said the newspaper's jealousy of television may have diminished the story's impact. "You have an entrenched senator and a single paper in town with no competition," he said.