Charlton Heston is a hard act to follow. But Richard Brandt, newly elected chairman of the American Film Institute's board of trustees, is planning a major role.

The 55-year-old chief executive officer of Trans-Lux Corp.--the Connecticut-based telecommunications firm that owns a large chain of movie theaters--is the first exhibitor to fill the top position; but then, Brandt says, "There haven't been too many people in the past to have held it."

The AFI has had four chairmen since its founding in 1967: Gregory Peck; Roger Stevens (now head of the Kennedy Center); and Heston, who had served from 1972 until he resigned last year to devote more time to other pursuits.

Brandt, an AFI trustee since 1971 and vice chairman since 1981, will preside over his first board meeting next month with a full roster of projects--each of which demands a major fund-raising effort.

"There are three items that are particularly important right now," he says. One is to secure the future of the industry's endangered artifacts. "It has been declared that the '80s will be the decade of preservation," he says, and "it's an emergency. If we don't preserve them in the next few years, we're going to lose a lot of film that is wasting away and is going to deteriorate. We're particularly concerned with the nitrate films of the '20s and '30s--which is not only explosive but deteriorates--and with the earlier color films of the '40s and '50s," many of which are fading badly.

Copying these decaying originals on modern stock, he estimates, will cost about $200 million and involve a joint effort among universities, archives and the Library of Congress, all coordinated by the AFI.

Another goal: Adequate financing for the AFI's recently acquired West Coast campus, a former Catholic school which houses the growing Center for Advanced Film Study. "We need funding both for the purchase price and for renovations," Brandt says, as well as for increased enrollment. "It'll mean a special fund-raising job among private donors and corporations as well as our 140,000 members."

Brandt also wants to oversee "the spread of the institute on a national basis. We are perceived as a Washington and Los Angeles operation, and admittedly a lot of our activities take place there. What is not perceived is that lots of the work in our outreach program takes place elsewhere--seminars, presentations at colleges, media centers supported by the National Endowment for the Arts--as we attempt to bring the art, culture and educational side of film throughout the nation. We're not doing it well enough. It takes a good deal of bucks. But along with that, it takes the energy."

As an example of this cinema evangelism, Brandt cites the coming October premiere of "The Right Stuff," which will be held first in Washington, then in Atlanta and Dallas.

This is national outreach? "Well, basically that's a fund-raising event," he says. "But it's also a motion-picture event--and in cities that don't traditionally have these events."

Earlier this summer, AFI director Jean Firstenberg announced that budget considerations had forced a board-mandated cutback in staff positions. Yet Brandt is unabashedly optimistic about the financial future. "Up to now, we've been a fairly young organization. But we're entering our mature teen-age period. My goal is to create an endowment. Most schools have them, but don't get them right away--it took Harvard and Yale centuries to do it."

That kind of stability is especially attractive since at present one-third of AFI's yearly expenditures of about $9.4 million comes from the NEA and is thus subject to the vagaries of congressional largesse.

Brandt isn't worried: "I believe government funding for the arts is here to stay. Sure, we've been through a tremendous recession, and we're going to have to re-examine our priorities--the arts against, say, food stamps. But in the long run, government--that is, all of us as individuals--need to be in the arts. The Medicis don't exist. My suspicion is that the arts budget will grow over the next 10 years. And as the major 20th-century art form, film will participate in that growth." Nonetheless, he looks forward to the day when "the largest part of our budget would be supplied by invested funds."

That means squeezing the studios. They've been "very supportive," he says, "but the industry is never generous enough." This despite the fact that the movie market has "grown fairly nicely over the last four or five years," broadening its range of target audiences and "beginning to bring back into the theaters the older generations that had been lost." Why? In part, he says, "it has something to do with the advent of cable, especially for-pay cable. Much more film is being watched. And much of what was viewed 10 years ago for free is now being paid for. Because there are so many kinds of outlets, there's more need for film, for scripts of all sorts aimed at different kinds of audiences. It's a very exciting trend."

And as the studios prosper, he says, so will AFI: "We're not part of the film industry, and so we have to stand in line. I just hope to be at the front of that line."