David Chambers who directed "The National Health" for the opening of the Arena Stage season will be in charge of production at the theater for the 1978-'79 and '79-'80 seasons.

Chambers' appointment as associate producing director of Arena was announced yesterday by producing director Zelda Fichandler co-founder of the theater which opened in 1950. Fichandler has planned every one of the Arena seasons since but feels that attention must be paid to the institution's and her own creative futures.

"The post of an associate producing director for Arena Stage, once held by Edwin Sherin, has been standing open for a number of years waiting for the right person to come along." Fichandler observed "David has been working with the Arena family for three years now and we share a common outlook on basic Arena principals."

Thomas C. Fichandler the huaband from whom Zelda is separated will continue in his post as executive director of the theater. He is heartily in ravor of the new appointment seeing Chambers' record as indicative of the theater's immediate future.

A 32 year old graduate of the Yale University School of Drama, Chambers previously staged "A History of the American Film," "Streamers," "Forever Yours, Marie-Lou" and "What the Babe Said" on Arena's three stages. His direction of "Medal of Honor Rag," for the Folger Theater Group, was his Washington introduction and he also re-staged at Ford's Theater "The Portable Pioneer and Prairie Show," which he had written and produced for the Tyrone Guthrie Theater, Minneapolis.

Besides directing fof the New York Shakespeare Festival, the Manhattan Theater Club and the Theater Company of Boston, Chambers has taught at Brooklyn College and the State University of New York at Buffalo and created scripts for the CBS-TV Bicentennial Minutes series and for the National Park Service.

Zelda Fichandler will resume full production responsibilities for the 1980-'81 season and very possibly will direct one or two productions for the seasons she has not planned. Next March she will move from her present office in the Kreeger Theater wing of the building to the one she occupied in the Arena wing before the Kreeger was built in 1970.

"What will happen," she wa s asked yesterday, "should you attend a rehearsal of a Chambers production and disagree with how it's being done?"

"David and I now have worked together so closely," she responded, "that I suspect he would see a certain expression in my eyes and ask: 'What is it that bothers you?' And I'd tell him.

"I'm not even certain that would happen," she continued. "They will be his seasons and I just may not always go to rehearsals.

"The entire point of this is to infuse new blood into the institution and selfishly perhaps, into my mind. I was 25 when I began working on the idea of Arena and though I've tried to take time off in the past, once 11 years ago and again in '73, I never really did so.The first time there were the Kreeger plans, the second time involved preparing for our tour to the Soveit Union.

"Now it's a different world, changes all the time and I'm not thinking of this as a sabbatical nor a leave-of-absence.

"David's appointment means I won't have to think of the planning a year in advance. I will be able to go around and see things, what others are doing and also be free to accept some of the directing asignments I'm offered. I want to expand my thinking and my activities.

"But I'll be taking in impressions for Arena. It is certainly, where my heart and mind are and probably always will be. I'd thought of resigning, leaving completely, but I knew that would never satisfy me.

"It's the board to whom I am grateful. It has accepted my recommendations for a Literary Manager, the post Douglas C. Wager has taken on. It has encouraged me to fill the vacant post of associate director. David and I have talked of this since last March, agreeing on the company idea, the kind of repertory that best expresses a contemporary theater and its connection with life.

Chambers won't move into Fichandler's office until March. He first will stage "Green Pond," by Robert Montgomery and Mel Marvin. Off-Boardway return to Arena to direct Trevor Griffiths "Comedians" and then stage Christopher Durangs "A History of the American Film," which he directed last season at Arena, for Broadway.