From Associated Press:
ATLANTA -- The Federal Aviation Administration is ordering U.S. airlines to conduct safety inspections to look for cracking on overwing frames on certain MD-80 series aircraft, a directive that could be a headache for an industry reeling from soaring fuel prices.

The airworthiness directive, listed in the Federal Register on Tuesday, affects 670 MD-81, MD-82, MD-83, MD-87 and MD-88 aircraft registered in the United States.

American Airlines, a unit of Fort Worth, Texas-based AMR Corp., has 212 MD-82s and 86 MD-83s, while Atlanta-based Delta Air Lines Inc. has 117 MD-88s.

Representatives of both carriers said their airlines would comply with the directive, which requires the inspections on the affected aircraft and all applicable corrective actions to be completed within two years or before the accumulation of 20,000 total flight cycles, whichever occurs later. Repeat inspections will be required at regular intervals.

The directive, which the FAA estimates will cost U.S. operators $214,400 per inspection cycle, resulted from reports of cracked overwing frames. It takes effect Aug. 12.

The FAA says such cracking could sever the frame, increase the loading of adjacent frames, and result in damage to adjacent structures and loss of overall structural integrity of the plane.

In April, American grounded its MD-80 fleet for inspections related to electrical wiring. Those inspections were the result of an FAA safety audit. More than 3,000 flights were canceled, costing the airline tens of millions of dollars in lost ticket sales. At the time, Alaska Air Group Inc.'s Alaska Airlines, Midwest Air Group Inc.'s Midwest Airlines and Delta each canceled a small number of flights on MD-80 series aircraft.

The Air Transport Association, on behalf of American, told the FAA as it was considering the directive that a 24-month compliance period for the initial inspections would be overly burdensome. The group requested doubling the compliance period to 48 months.

The FAA disagreed, arguing that the 24-month period is "considered appropriate in light of the characteristics of crack growth, the probability of crack initiation, and the ability of the operators to integrate the required actions into established maintenance practices."

The notice of the airworthiness directive says the action is interim. It says the manufacturer is developing a modification that will address the unsafe condition identified in the directive. Once the modification is available, the FAA may consider additional rulemaking.