When Frank C. Carlucci was brought in to rescue the National Security Council staff from itself last January, he asked a holdover official why the place had so many secretaries. "I was told we needed all of them because we worked in shifts through the weekends," Carlucci said in an interview last week. "I said the hell we do. We probably worked two or three weekends during the year. Most nights, I went home by 6 o'clock."

This dedication to normalcy is a useful clue to the character of Carlucci, whose calm professionalism has made him an accomplished trouble-shooter through seven presidencies.

When Carlucci became President Reagan's fifth national security adviser in six years, he entered a White House shaken by revelations of the Iran-contra affair. The NSC staff was demoralized and divided between factions labeled "ideologues" and "pragmatists." Outsiders viewed the staff as a government within a government, epitomized by the messianic exploits of Lt. Col. Oliver L. North. Insiders noted the insecurities and scapegoating displayed by survivors of the unfolding scandal.

This portrait may have been unfair to dozens of hard-working men and women on the NSC staff who were not part of the North cabal and didn't share his zealotry. Many of them had performed professionally under a bewildering succession of bosses and a president whose answer to a charge of misconduct was basically a plea of ignorance.

But there is no doubt that the NSC staff had wandered far afield from its legitimate function of providing impartial advice on conflicting policy options. The report of the congressional committees on the Iran-contra affair observed that national security adviser John M. Poindexter misinformed Reagan that Iraq was winning its war against Iran in an effort to encourage the arms-for-hostages swap. It also found that the NSC staff had provided covert assistance that the CIA "could not or would not furnish" and concluded that this was "a dangerous misuse of the NSC staff."

Long before this report, Carlucci had reached many of the same conclusions and acted on them. As a veteran bureaucrat, he realized the importance of capitalizing quickly on the political mandate for change. The backlash against the Iran-contra affair had forced Reagan to prohibit further covert actions by the NSC staff, and Carlucci also did away with oral or retroactive "findings" of the sort used to justify the arms deal.

Within the NSC staff, Carlucci swiftly abolished the political-military unit that had served as North's launching pad. "I could never figure out what it did," he said. "In any case, it made no sense to me because almost everything we do involves political and military affairs. The way it was set up simply invited trouble, and, of course, trouble came along."

As he had done in other assignments, Carlucci brought in his own trusted team, including Army Lt. Gen. Colin L. Powell, now his designated successor. He fired some people and transferred others. He left open the door to his office, a symbolic act that to the White House staff signified the end of the separate worlds of "NSC and non-NSC."

Above all, he restored an everyday sense of normalcy in which NSC analysts were encouraged to give sensible, professional advice rather than engage in private crusades to save the world.

"We set out to restore the credibility of the institution, to restore it to its proper role as an interagency body," Carlucci said. "That is its honest broker role, and we set out to reestablish it. We took the NSC out of operations."

Carlucci has met many challenges during his productive government career. Some would say that he performed his most vital service as ambassador to Portugal in 1975 when he led the effort to keep that nation in the democratic camp after Secretary of State Henry A. Kissinger had abandoned the task. Now, Carlucci faces another challenge at the Defense Department as Reagan struggles to leave a legacy of nuclear arms reduction.

However this comes out, Carlucci demonstrated in a tumultuous year at the NSC that professionalism and common sense are more valuable in the pursuit of national security than unrestrained ideological fervor. It would have been better had Ollie North worked fewer weekends.

Reaganism of the Week: Speaking to supporters here last Monday, the president said his missile-defense plan would provide protection from "outlaw regimes" and added: "We've had madmen come to power before in countries in the world."