The Washington Redskins added a bit of relatively reasonable health insurance at tight end yesterday when they traded a pair of eighth-round draft choices to the Miami Dolphins for veteran Jim Mandich.

The Dolphins received eigth-round picks in the 1979 and 1980 drafts for the 29-year-old Mandich, a lightweight tight end at 6-foot-2 and 215 pounds. He is known primarily for his clutch catches and acrobatic pass-receiving skills in eight seasons with the Dolphins. Mandich signed a three-year contract in the $70,000-a-year range.

General Manager Bobby Beathard said yesterday the Redskins obtained Mandich because there are still some doubts about the physical condition of starter Jean Fugett and veteran Tom Mitchell, recently acquired in a trade with the 49ers.

Fugett underwent knee surgery to remove damaged cartilage March 29 and "there's still a question whether Jean will be ready by the start of the season," Beathard said.

Mitchell played the 1977 season with a weak knee, and there is now some question as to whether he will be able to pass a physical.

"We had known about Tom's condition," Redskin Coach Jack Pardee said yesterday. "He played with that knee last year, but it's not in that good shape. That really leaves us with only one healthy tight end, Reggie Haynes (a rookie on the injured reserve list a year ago), and that's a little scary.

"Mandich is experienced, in the Jerry Smith mold. He's not an overpowering blocker, but he's an excellent receiver. We got him to make sure that we're set at the position and not exposed in case the other two don't come around."

Mandich spent most of the 1977 season on the Miami bench, playing behind Andre Tillman and Loaird McCreary. He caught only six passes for 6 yeards.

Mandich's most productive season was in 1974, when he caught 33 passes, six for touchdowns. Going into the 1977 season, one of every five completions to Mandich went for a touchdown.

"He's going to be an asset," Beathard said. "He's not a big strong blocking tight end, but he's a fighter, a pesky receiver who can also do a good job on the special teams. He makes big plays, and he'll help us.

"I don't think Jean's knee is going to be a problem. But anyone who has surgery as late in that year as he did, you have to be concerned. I felt we had to cover ourselves, and getting Jim at that price was a bargain."

Beathard also said he had spoken with Billy Kilmer Wednesday and the veteran quarterback told him that he would definitely not report to the Redskins' minicamp starting Thursday unless he has signed a new two-year contract.