Aloysius (Pete) Kilgallen, 73, a retired research and development engineer with the Navy Department's bureau of weapons, died Wednesday at Arlington Hospital after a stroke.

He had retired from the bureau's naval weapons system office in 1966 after 27 years with the bureau.

Mr. Kilgallen then served as a consulting engineer to a number of Defense Department contractors in research and development of tactical weapons systems. He retired for a second time two years ago.

Born in Pittsburgh, he received a degree in electrical engineering from the University of Pittsburgh in 1925.

He worked for the Westinghouse Electric Co. in Pittsburgh and then as an engineer for the state of pennsylvania in Harrisburg before coming here in 1939 to join the bureau of naval weapons.

His position included head of the radar development section, senior systems engineer of surface-launched weapons system and assistant technical director for engineering in the research group of the weapons system office.

Mr. Kilgallen had traveled extensively to England, France, Italy and the Netherlands in his work.

He took advanced courses at George Washington University and Johns Hopkins University, and wrote numberous papers on missiles and missile systems.

He is survived by his wife, Grace Mcbride Kilgallen, of the home in Arlington; three children, Patrick A., of Los Angeles, Mary Macmanus, of LaDue, Mo., and Grace Post, of Buffalo, N.Y.; two brothers, John, of St. Petersburg, Fla., and Raymond, of New York City; a sister, Mary K. Hale, of Arlington, and 10 grandchildren.

The family suggests that expressions of sympathy may be in the form of contributions to the Msgr. Taylor Memorial Fund of the Cathedral of St. Thomas More in Arlington.