As a result of the AD, Decathlon planes -- any model no. 8KCAB equipped with part number 4-2142 exposed balance ailerons -- now require “fabrication and installation of a placard to prohibit aerobatic flight,” which limits aerobatic flight for the 10 flight hours allowed prior to an inspection of the aileron hinge rib and support. If no cracks are found during the inspection, the placard can be removed and aerobatic flight can be continued. If cracks are discovered, aerobatic flight is prohibited until an FAA-approved repair is performed. American Champion Aircraft issued a service letter in February, requiring “repetitive inspections”; however, the letter does not require a placard, and inspection results would go to the company and not the FAA.