A highly regarded principal of a model Ann Arundel County elementary school has become the second Maryland principal in less than two years to leave his post after improprieties in the administration of standardized tests were uncovered.

The sudden retirement of the principal at Brooklyn Park Elementary School who had been three times selected as Maryland's Elementary School Principal of the Year followed reports that students were given too much time to finish the tests, thus artificially boosting scores.

George E. Surgeon had been "an outstanding principal for many years," county school Supt. Edward J. Anderson said yesterday from a state education conference in Easton. "This whole chain of events is very unfortunate for everyone concerned."

The purpose of testing, Anderson said, is not to compare schools or students but to provide information to better meet student's educational needs.

"This business of making comparisons between schools is causing unhealthy situations to develop. This would be one of them," he said.

Rivalry between school principals has sparked similar but infrequent episodes of rule-bending in the administration of the so-called Iowa tests given to measure student skills in reading, vocabulary and math. One such incident was uncovered a few years ago in New York City when principals of rival schools complained about suspiciously high scores, according to testing officials.

Another occurred in 1977 when impressive test scores from a small, low-income Worcester County school be-dazzled urban educators until it was learned that the students had been "pretested." Facing departmental discipline, the principal resigned.

In the case of Surgeon, his retirement July 1 after 24 years as principal of Brooklyn Park, officially for health reasons, placed him beyond the school board's jurisdiction. "Once retired what can you do?" Anderson said. "I'm not sure any law as broken," he added. Surgeon could not be reached for comment.

According to county officials, Surgeon's problems arose from the administration of the so-called Iowa tests to his students in the middle-class suburb just south of Baltimore. The tests are not valid unless they are given without variation across the country.

In this case, officials said, students were given more time than allowed to finish test segments.

"In previous years," according to Dr. Timothy Dangel, county testing coordinator, Brooklyn Park scores had been "very acceptable given the ability of students." In absolute figures, he said, the school had ranked in the middle of the county system. When compared with the students' ability as measured by the tests, Brooklyn Park students had the highest ranking in the county, he said.

Scores for tests administered last spring to Brooklyn Park third and fifth graders were flagged before their general release "because procedures were not followed," Dangel said.

"If we see scores beyond predictability, what'd you'd expect knowing the youngsters in the school, we check," said Deputy Superintendent Berry Carter. "We talked with people about how the tests were administered. We retested."

When the tests are given, Carter said, "You can't answer questions. You can't give additional time. If you do, you give youngsters an advantage and invalidate the test."