The Federal Aviation Administration has published a proposed airworthiness directive in the Federal Register covering certain Piaggio Model P-180 airplanes, a type now held by Baykar Piaggio Aerospace. The proposal follows a report that corrosion and cracking were discovered near the heads of fasteners that attach external reinforcement doublers to the lower skin of the main wing. Under the proposed rule, operators would have to carry out repeated high frequency eddy current inspections of the lower skin reinforcement area and take corrective measures where the inspections reveal problems.