When the Capitals skate onto the ice tonight in Winnipeg, Manitoba, leading Washington scorer Dennis Maruk will be listening via bedside radio at Arlington Hospital.

Maruk is not playing tonight, and most likely not for the rest of the season. He underwent surgery yesterday for a torn ligament in his right knee. s

Maruk -- and Washington's loyal core of fans -- will be listening rather than watching on television because prohibitive line charges prompted WDCA-TV-20 to scrap the scheduled telecast.

It is a game worth watching, too, because Winnipeg left wing Bobby Hull, one of the great players in National Hockey League history, will be making his first NHL appearance since April 23, 1972.

Hull, who defected to the World Hockey Association in 1972, last played for the Jets on Oct. 18, 1978. He has been working out twice a day and said, "I hope to be out there, if (Tom) McVie doesn't kill me first."

McVie, the former Washington coach and disciplinarian, will be leading his Jets against the Capitals for the first time in a regular-season game. Although Winnipeg, the last champion of the WHA under McVie's guidance, was denuded in the NHL expansion draft, the Jets have posted a 4-5-1 record and are only two points out of first place in the Smythe Division.

A couple of Capitals will be making their season debuts tonight. Right wing Mark Lofthouse and center Claude Noel were called up from the Hershey farm club, with right wing Tony Cassolato sent back after posting one assist in four games.

Lofthouse, a familiar figure here over the last two seasons, recorded seven goals and three assists in nine AHL games to earn his promotion. Noel, who had four goals and three assists, formerly played for Hershey as a Buffalo farmhand. He signed a Washington contract in August.

Maruk is the latest in a long line of Capitals to suffer a disabling injury, following the examples of Greg Joly (twice), Jim Hrycuik, Willy Brossart, Blair Stewart (three times), Ace Bailey, Mike Lampman, Yvon Labre (twice), Jack Lynch, Bill Riley, Rick Green, Pete Scamurra, Greg Polis, Ryan Walter and Bob Sirois.

When the Caps were beset with a series of annoying but minor injuries this fall, it was hoped they might avoid the more crippling variety. However, Maruk took what appeared to be a routine check from Thomas Gradin in the closing minutes of Saturday's game at Vancouver, felt considerable pain the next day and on Tuesday learned from arthroscopic examination that a medical collateral ligament had been torn in his right knee. e

It was a shocking development for both the Capitals and Maruk, who had not suffered a major injury during a long junior career and four previous NHL seasons. His only operation had been the result of an appendicitis attack as a child.

Maruk scored eight goals in eight games and seemed headed for a sensational season. Even his defensive play had perked up, and he was one of the team's few plus players, at plus two.

"The way it appears, any games we get out of Dennis the rest of this year will be a bonus," said General Manager Max McNab."It will take a miracle healing process to get him back. He'll be in a cast six to eight weeks and the nature of this injury calls for a long rehabilitation period.

"It's a terrible shame for Dennis. With . . . the supporting cast behind him he seemed sure to get over 100 points this year. And the play seemed so inconsequential. With a guy like Gradin, you know it's no hatchet job or malice aforethought, just an unfortunate accident."

The supporting cast provides the only consolation for the Capitals. In another season, the loss of a scorer like Maruk would have spelled instant disaster. Now, however, Washington has many players who can score. The victory over Edmonton and tie against Montreal without both Maruk and Sirois, who is still ailing indicate the team is capable of playing well in the absence of top players.

Hull is returning to the Jets at age 40 not to hype attendance, but to give a surprising team the benefit of his experience and potect slap shot.

The last thing snow-covered Winnipeg needs right now is more hockey fans. The Winnipeg Arena has been rebuilt to boost seating capacity about 14,000, but 3,000 balcony seats have been questioned as unsafe and they will be empty tonight.

One of the big reasons for the excellent play by a team that was generally consigned to the NHL depths has been the low goals-against figure, only 31 in 10 games compared to Washington's 46. Goalie Gary Smith, the former Capital bust, is among the NHL leaders with a 2.63 mark and has been in the nets for all four victories.

"With an expansion hockey club the first thing you have to do is watch the goals against," McVie said. "But here we're watching it so close we've forgotten to get any goals for. It's like a cave-in in a mine. You hold the wall, then run to another side to stop the flood, and then you run back."