COEUR d’ALENE — A lawsuit was filed Monday in 1st District Court in Kootenai County against the Hayden Chamber of Commerce for tens of thousands of dollars owed by an airshow infamously known as Thunder Over the Prairie.

The June 2004 event is remembered for racking up $238,000 in debt.

The plaintiffs in the case, Solar G. Larsen and Dana N. Larsen, are trustees of the Larsen Revocable Living Trust. They are the sons of Bjarne B. Larsen, who loaned the chamber $50,000 for the air show.

The Larsens said in the lawsuit that the chamber agreed to an interest assessment of $15,000 by June 30, 2004. The lawsuit said interest after that date started accruing at 12 percent annually.

The lawsuit said the chamber made six payments over the years totaling $18,100.

The chamber “owes to plaintiffs the unpaid principal balance of $50,000 plus accrued interest in the sum of $64,856.60,” according to the suit documents.

The Larsens sent a demand letter to the chamber in November, but said the chamber refused to pay up. They said the chamber has been “unjustly enriched.”

In the lawsuit, the family also is asking for attorney fees.

Bjarne Larsen was, at the time of the airshow, a Hayden chamber board member and landlord for the nonprofit.

“This show was to put Hayden on the map,” Larsen told the Press for a July 2004 article. “Obviously we got on the map for the wrong reasons.”

Neither Judi Cronin, the current president of the chamber’s board of directors, nor Sean Moglia, vice president of the board, could immediately be reached for comment Thursday.

Mark Ellingsen, a Coeur d’Alene attorney for the Larsens, is out of the office this week and unavailable for comment.