EASA 2023-0007

Requires a one-time detailed inspection of the horizontal stabilizer central box, reporting of the results to Piaggio Aerospace for determination of the severity level of the corrosion; depending on the outcome, repetitive detailed inspections of the central box; and any necessary corrective action(s). For airplanes found to have level 3 corrosion is found, AD requires repair or replacement of the horizontal stabilizer, which terminates the repetitive inspections. Prompted by an occurrence where, during scheduled maintenance, corrosion was found inside the horizontal stabilizer central box. Subsequent investigation and inspection of 16 other airplanes representative of the the complete P.180 fleet revealed corrosion at different levels of severity on the various aluminium alloy reinforcements in the horizontal stabilizer central box. This corrosion was caused by formation of a humid environment inside the box due to water ingress and/or condensation, which promoted galvanic phenomena. Further investigation revealed that airplanes subjected to prolonged inactivity and parked outside are more prone to suffer from corrosion damage.