More than 2,300 U.S.-registered Robinson R22- and R44-model helicopters must continue inspecting the outboard sections of the helicopter's metal main rotor skins for signs of debonding before each flight, a requirement that also applies to new factory models with modified blades. The checks are part of an AD issued by the FAA this month, prompted by 11 reports of blade debonding, some of which occurred in flight and caused the pilot "to feel excessive vibrations," according to the FAA. The AD also requires owners who have not completed earlier service bulletins issued by Robinson, calling for the pre-flight checks as well as a one-time detailed inspection, to perform a similar intensive survey within 10 hours time-in-service starting 18 January. That check includes a 10X magnification inspection of the skin-to-spar bond line on the lower surface of the blade, a "tap test" to detect skin-to-spar bond separation in the same area, and removal of both main rotor tip covers to check for corrosion or other issues that could cause debonding. MORE