For the third time in four years, the Naval Academy has lost a starting quarterback during a season. Junior Bill Byrne underwent emergency surgery to remove his torn spleen late Saturday night, only hours after he set six school passing records.

Navy officials said yesterday it isn't certain how Byrne suffered the injury, and it probably never will be. Byrne was eating dinner at about 8:30 p.m. Saturday when he began experiencing spasms in his shoulders, Navy Coach Gary Tranquill said.

Byrne asked to be taken to sick bay, where he was examined by the team's physician, Lt. Cmdr. Tom Harries. Byrne immediately was taken to Anne Arundel General Hospital, where the surgery took place.

Tranquill said he went to the hospital about noon yesterday, and although he didn't see Byrne, understood he was in good condition and spirits.

"Billy's mom and dad are here and they said he was doing okay," Tranquill said.

Byrne had to leave last week's game at Notre Dame after a hard tackle. "But he didn't have any difficulties during the week," Tranquill said. Byrne wore his flak jacket as usual Saturday in a game against Syracuse that Navy lost, 24-20, in Annapolis although Byrne threw for 399 yards in the most prolific passing day ever for a Navy quarterback.

The Midshipmen were attempting a comeback when Byrne was knocked out of the game on the next-to-last play.

"You take another bump or jolt and it could have had a big effect," Tranquill said. "But it looked like he got hit almost in the head. He had his bell rung, which is why we had to take him out. It's just impossible to tell."

Tranquill, following another close loss, obviously was in low spirits. He said Bob Misch, who replaced Byrne in the final four games last season, would become the starting quarterback.

Byrne completed 37 of 52 passes Saturday.

Byrne's injury puts Tranquill and the Midshipmen in a familiar position. In each of Tranquill's four years as head coach at Navy, the starting quarterback has been knocked out in the second half of the season. Three of those times, he didn't return.

In 1982, Tranquill's first season, Marco Pagnanelli suffered a broken leg in the seventh game of the season, against The Citadel, and was out for the rest of the year.

In 1983, Ricky Williamson injured his knee against South Carolina and limped through the final game against Army.

Last season, Byrne suffered a broken ankle in the seventh game, against Notre Dame, and missed the final four games.

"Every year, every single year," Tranquill said, his voice trailing off.