"Amazing Grace," the mini-series currently being heard on "Children's Radio Theatre," is a bit of a departure for the Peabody Award-winning program, heard on WPFW every Saturday at 8 a.m. "We wanted to do something a little more serious," says CRT director Joan Bellsey. "I had an idea a few years ago about a mother and daughter team, and at first the idea was to do them as sort of superheroines. But as time went on we changed it to deal with more serious topics and social issues that we hadn't dealt with before. It went through a lot of transformations.

"I also wanted to do something for the actors," she adds. "They were tired of playing animal parts." In the series, which will run through Dec. 29, the mother-daughter team confronts a number of community problems. The first program dealt with an old sea captain's coming to terms with the whales he has always hunted. "Silent Water," this week's show, is about a deaf girl who is unhappy at school and feels at a disadvantage because of her deafness. "One of her classmates gets stuck in a manhole after chasing a ball on the playground and she decides to go down after him," Bellsey says. "It's a way for her to get the respect of her class; her deafness means she won't be distracted by the sounds underground. And she ends up saving his life, getting the respect and being very proud of herself."

Other programs deal with students banding together to head off a parents group trying to remove controversial books from the school library, a boy's acceptance of his grandmother's impending death and a father-son struggle for mutual respect and understanding. Cassettes of these shows, and all of CRT's fine programs, are available by mail order. For a catalogue, write to Children's Radio Theatre, 1314 14th St. NW, Washington, D.C. 20005.