The FAA recently published an airworthiness directive—2020-26-16—covering many single-engine Pipers that carry either a PA-28 or PA-32 model number. “This AD was prompted by a report of a wing separation caused by fatigue cracking in a visually inaccessible area of the lower main wing spar cap,” the directive said. “This AD requires calculating the factored service hours for each main wing spar to determine when an inspection is required, inspecting the lower main wing spar bolt holes for cracks, and replacing any cracked main wing spars. The FAA is issuing this AD to address the unsafe condition on these products,” adding that failure to comply with the directive could lead to failure of a main wing spar.
The AD will require the installation of inspection panels close to the main wing spars to give technicians access to that area when searching for corrosion. “After the NPRM was issued, Piper revised its service information to add a minimum thickness dimension for the top inboard wing skin and to include procedures for reapplying corrosion preventive compound if removed during the inspection,” the AD continued. “Also, at the request of some commenters, the FAA replaced the proposal in the NPRM to install access panels for the visual inspection with optional access methods: The use of existing access panels, installation of access panels, accessing the area during a concurrent inspection, or using a borescope through existing holes or openings. In the SNPRM, the FAA proposed to inspect the left and right main wing spar for corrosion, and, if corrosion is found, take all necessary corrective actions.”