The government is proposing modifications to older Boeing 737s to help the aging aircraft stand up against the corrosion and crack problems discovered after the breakup of an Aloha Airlines jet last month.

The Federal Aviation Administration on Thursday issued two proposed "airworthiness directives" designed to serve as long-term solutions to the structural problems identified after a 20-foot section of the Aloha plane tore away during flight on April 28.While some ongoing intensified inspections would be required under the proposed rules, airlines could avoid even more intensive and costly inspections once they completed the modifications.

"We're giving the airlines what we call a `terminating action,' something they can do so they don't have to continue to do these very expensive, repetitive inspections," FAA spokesman Fred Farrar said of the proposed modifications.

The rules cover, in varying degrees, the first 464 of the 737s built, but only an estimated 100 of those aircraft now are being operated by U.S. airlines.

The repairs were expected to take about 2,000 work hours per plane, with the total cost for work on the 100 planes operated by U.S. carriers estimated at $8 million.

"This proposal is prompted by reports of numerous cracks found during inspections of airplanes that have accumulated more than 40,000 landings," one of the FAA proposals states. "This condition, if not corrected, could result in rapid decompression of the airplane."

The Aloha jetliner was 19 years old and had made nearly 89,000 landings.