Not very often is a powerful 12-term congressman confronted by a tiny 8-year-old child lobbyist, but it has happened on the oldest of issues -- the automobile safety airbag.

The confrontation matches Rep. John D. Dingell (D-Mich.) against Yvonne Frazier in one of the more emotional legislative skirmishes of recent weeks.

Yvonne, daughter of Mr. And Mrs. Victor Grabis of Oxon Hill, Md., was saved from injury by an auto airbag in a severe accident two years ago in Florida.

The National Committee for Automobile Crash Protection, a coalition of medical, insurance and consumer groups, has had Yvonne on Capitol Hill in recent days as part of a campaign to thwart Dingell.

The campaign reached fever pitch yesterday just before the House was Scheduled to debate a Dingell amendment to the Department of Transportation appropriations bill, banning spending for a year on passive automobile safety devices, such as airbags.

The House postponeed action on the DOT bill, but by later afternoon both sides in the debate were hurling verbal bombs at each other.

It went this way:

Dingell called a news confernce to accuse DOT of withholding from Congress and the public information about the risk of exploring and burning airbags.

Joan Claybrook, head of DOT's National Highway Traffic Safety Administration, wrote Dingell at length describing cooperation her staff had given him. She told reporters he was raising "trumped-up charges" and pushing "a phony issue."

Claybrook joined Reps. Bob Eckhardt (D-Tex.) and James H. Scheuer (D-N.Y.) at a news conference, with Yvonne in the wings, to call for defeat of the Dingell amendment.

Ralph Nader, whose crusades made auto safety a way of life, said of Dingell's charges: "It's another in a long series of spectacular deceptions and distortions by Dingell to defeat a proven and major live-saving technology for our motor vehicles."

The basic of Dingell's allegations was that NHTSA had suppressed deliberately films of airbag tests in which a dummy representing a child was burned when a bag exploded.

His aim was a generate House support for the amendment that he and Rep. James Broyhill (R-N.C.) want on the DOT spending bill -- banning NHTSA from acting on passive safety restraints for a year.

Automobile manufacturers by law still have begin installing the passive restraints -- airbags, automatic seat belts or other approved devices -- in some of their 1982 model fleets.

Claybrook said the film Dingell referred to involved a "red herring." She said the tests had nothing to do with the inflators used on airbags.

Claybrook said that automakers and suppliers are at a crucial point in their 1982 designs. If the House bans spending by DOT for a year, she said, the industry could back away from airbags.

The crash-protection committee and DOT, with the help of Yvonne Frazier and other motorists who were saved by airbags, all have been on the Hill telling their story. Yvonne's grandmother happened to have purchased one of 10,000 special equipped GM vehicles marketed during 1974-76.

How did it feel when the airbag inflated? Yvonne was asked. "Like a pillow flight," she said. CAPTION: Picture, Rep. JOHN D. DINGELL . . . says DOT withheld safety data