The Federal Aviation Administration told Congress this week that it soon will order more than 160 structural changes in Boeing Co. planes and more later for other manufacturers to deal with America's aging aircraft.

Anthony Broderick, the FAA's associate administrator for regulation and certification, said his agency hopes by the end of 1990 to have added nearly 1,000 inspectors, bringing its total to nearly 3,000.Broderick testified before the Aviation Subcommittee of the Senate Commerce, Science and Transportation Committee about steps being taken by the FAA, by airlines and by manufacturers to ensure the safety of older planes.

The problems of aging aircraft were highlighted a year ago when a 19-year-old Aloha Airlines Boeing 737 lost a part of its upper fuselage in flight, causing the death of a flight attendant. Incidents since then have fueled debate.

The FAA already has ordered rivets installed on the first 291 of the Boeing 737s produced, replacing a "cold bonding" process on fuselage skins, and it has ordered rivet replacements in the 727-model planes.

"Late this month or early next month we should issue the first required series of changes stemming from" a joint FAA-industry study of replacing various inspections with design modifications or repairs, Broderick told senators Tuesday. "Over 160 structural changes will be proposed for Boeing 727, 737 and 747 aircraft."

Broderick said as study groups finish examining other aircraft, such as the models produced by Douglas, Lockheed, Fokker, Airbus, Convair and British Aircraft Corp., changes also will be ordered for their older planes.

He said the FAA is working on a supplemental inspection program for corrosion, a particular problem for planes operated in salt air environments such as the Aloha aircraft.

The average age of the world's airline jet fleet has risen from eight years in 1980 to 12 years in 1988, and it is projected to reach about 15 years by the turn of the century.