A group of aviation industry and government safety experts recommended Tuesday $800 million worth of mandatory work on older airliners to ensure safety of the nation's aging airliner fleet.

The unprecedented program, if adopted by the Federal Aviation Administration, would affect more than 1,300 early Boeing 747, 737 and 727 models at a cost of more than $600,000 each.The Aging Aircraft Task Force's working group on older Boeing airliners drew up its final recommendations Tuesday morning just prior to a news conference releasing the details. The Air Transport Association, which represents major airlines, organized the task force.

Clyde Kizer, an ATA vice president, said none of the recommended work, which would involve planes flown by foreign carriers as well as U.S. airlines, was considered urgent. "There are no dangerous aircraft out there flying right now," he told reporters.

Representatives of Delta and United, who also participated in the news conference, said much of the work had already been done on their airliners and they anticipated no immeidate large expenses.

Some other major airlines also have made many of the changes recommended by the task force.

"Widescale modification or replacement of structural material, fittings and skin are being recommended on the basis of service experience," said a final draft of the report, which follows nine months of meetings and examination of more than 700 service bulletins issued by Boeing.

The recommendations adopt 150 of the bulletins and consolidate them into the form of one massive service bulletin to be issued by Boeing and presented to the FAA for possible adoption as an airworthiness directive.

The difference between a manufacturer's bulletin and an FAA airworthiness directive is that FAA orders are mandatory. Airliner operators will be given varying times by which to accomplish the changes, based on the amount of service an aircraft has had.

Other groups from the task force are looking at service recommendations affecting McDonnell Douglas DC-9s, DC-8s and DC-10s and airliners manufactured abroad to see what modifications will be needed to maintain their safety. Results of their work are expected before the end of the year.

The average age of the nearly 3,000 U.S. airliners is about 13 years, with half the planes in many major airlines' fleets well over 15 years old, according to Avmark, an appraisal and consulting firm.