Montgomery County Executive Sidney Kramer announced yesterday his appointment of an Olney civic activist and a Silver Spring real estate executive to the county Planning Board, saying the executive for the first time will have a voice in important growth decisions made by the board.

Carol G. Henry, former president of the Greater Olney Civic Association, and John P. Hewitt, former executive director of the Maryland-National Capital Park and Planning Commission who runs his family's real estate business, are expected to be approved by the County Council for four-year terms on the influential Planning Board.

The appointments -- the first under controversial state legislation giving the executive power to appoint two of the five board members -- are expected to change the political landscape of the board, which has since 1981 been dominated by Norman L. Christeller, the board's aggressive and persuasive chairman who is the only member to serve full time.

Christeller vigorously opposed the change in state law that was advocated by former executive Charles W. Gilchrist, who believed the executive should have more power over planning decisions.

With two members now appointed -- and, some critics say, answerable -- to the county executive, some observers suggest that factions may be developing between the new members and those members appointed by the seven-member County Council.

The new appointments had been seen as a means of better discerning Kramer's stance on the issue of growth in the county. Kramer has advocated "controlled and staged growth" but the business community's wholesale endorsement of him in the last election makes him suspect to some civic groups who believe he may be too prodevelopment.

Kramer, however, characterized the appointments as showing "balance." Introducing Henry and Hewitt at a morning news conference, Kramer pointed out one is male, the other female; one has a background in business (Hewitt), the other in civic affairs (Henry); one is a Democrat (Henry), the other is Republican (Hewitt); one is upcounty (Henry), the other is downcounty (Hewitt).

Later, in response to questions, Hewitt allowed he was "not a great lover of Art Deco" architecture but Henry said "I like Art Deco." Kramer then ad-libbed: "As you can see, I've given it balance." The Art Deco issue is expected to come into play when the Planning Board decides whether Art Deco-style structures in Silver Spring should be razed to make way for an expected development.

The redevelopment of Silver Spring is one of the controversial questions facing the board in coming months. However, Kramer stressed that Henry and Hewitt are being placed on the board with "no predetermined bias . . . including my own." He said he hoped to have a voice in decisions through his two appointments, but not control. The two, he said, are both "free thinkers" who will make their decisions based on the merits of an individual case.

Some of the tension of past development debates was evident yesterday, as Kramer faulted the Planning Board for not being responsive to both civic groups and business. Kramer said that he has had a problem in working with the current board and defined as his relationship with Christeller as "adequate."

Christeller said he believed the Planning Board has been responsive to the community but that many times the board comes under criticism because it doesn't give everyone everything he wants.

He said he hoped the board would continue its present operation in which "you don't have to be enemies if you disagree."

Henry and Hewitt are expected to assume the $12,600-a-year posts on July 1, succeeding Judith B. Heimann and Betty Ann Krahnke.

Other appointments announced by Kramer yesterday were Waymond D. Bray, a lawyer with McCants & Gerald of Silver Spring, to a $10,000, four-year term on the Washington Suburban Sanitary Commission, and the reappointment of Robert P. Will to the commission.