A Falls Church man who was arrested at National Airport on Tuesday when police discovered a shotgun and ammunition in his luggage pleaded guilty yesterday to carrying a weapon onto the airport grounds, according to a prosecutor in the U.S. attorney's office in Alexandria.

Kamal Abou-Zakia, a waiter at a Georgetown restaurant who was traveling with his family to their native Beirut when Federal Aviation Administration police discovered a 12-gauge pump-action shotgun, a BB gun, 48 rounds of shotgun ammunition and 150 rounds of .45-caliber pistol ammunition in his bags, was fined $100 and given a 60-day suspended sentence by U.S. Magistrate Quin S. Elson.

First Assistant U.S. Attorney Thomas Berger said Abou-Zakia, who could have received a maximum sentence of six months in jail and a $500 fine, was "checked out thoroughly with our intelligence sources, and as a result we let him plead to the offense."

Abou-Zakia was charged with carrying a dangerous article upon the airport grounds without prior permission of the airport manager, a federal offense. As part of his plea agreement, he forfeited ownership of the guns and ammunition, and Magistrate Elson also ordered that he not possess any firearms during his one-year, unsupervised probation.

Last night Abou-Zakia, a naturalized U.S. citizen, said that the weapons had been intended as a gift for a friend in Beirut and that the incident was "blown out of proportion." He said he plans to leave for Beirut with his wife and children on Saturday to visit other family members.