Federal income tax returns being mailed from Billings to Ogden, Utah, made up much of the mail on a light airplane that crashed in Idaho recently, Postal Service officials in Billings said Monday.

By Monday, postal officials said all but 8 pounds of the 387 pounds of mail on the flight to Salt Lake City had been recovered.Ted Blazina, director of marketing for the Billings post office, said 80 percent of the recovered mail was damaged, some beyond recognition.

The twin-engine Aero Commander 680 left Billings Logan International Airport at 8:03 p.m. last Friday with two men aboard.

Killed in the crash were pilot Dave Clark of Billings and mechanic Clarence Preble of Salt Lake City.

The airplane was owned by Corporate Air, which contracts with the U.S. Postal Service to fly mail. Both men were employed by the firm.

Postal Service employees from Pocatello went to the crash site Monday to collect the mail.

A portion of the mail on the plane was income tax returns mailed at Billings collection boxes on Friday, Blazina said. The tax returns were bound for the regional Internal Revenue Service in Ogden.

The damaged mail was taken to Salt Lake City, where Postal Service employees will attempt to piece the shredded mail back together. Blazina said they were unable to determine yet how much of it eventually can be sent to its destination.