AD 2020-24-05 Prompted By Reports Of Corrosion Found In An Area Of The Main Wing Spar Not Easily Accessible For Inspection

The FAA is adopting a new airworthiness directive (AD) for certain Piper Aircraft, Inc. (Piper) Models PA-28-140, PA-28-150, PA-28-160, PA-28-180, PA-28-235, PA-32-260, and PA-32-300 airplanes.

This AD was prompted by reports of corrosion found in an area of the main wing spar not easily accessible for inspection. This AD requires inspecting the left and right main wing spars for corrosion, and, if corrosion is found, taking all necessary corrective actions. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective December 28, 2020.

Supplementary Information: The FAA issued a supplemental notice of proposed rulemaking (SNPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain serial-numbered Piper Models PA-28-140, PA-28-150, PA-28-160, PA-28-180, PA-28-235, PA-32-260, and PA-32-300 airplanes. The SNPRM published in the Federal Register on August 4, 2020 (85 FR 47118). The FAA preceded the SNPRM with a notice of proposed rulemaking (NPRM) that published in the Federal Register on November 7, 2017 (82 FR 51583).

The NPRM proposed to require installing inspection access panels in the lower wing skin near the left and the right main wing spars (if not already there), inspecting for corrosion, and taking all necessary corrective actions if corrosion is found. The NPRM was prompted by reports of significant corrosion found in an area of the main wing spar not easily accessible for inspection.

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. 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.

Corrosion of the main wing spar, if not detected and corrected, could cause the main wing spar to fail with consequent loss of control of the airplane. The FAA is issuing this AD to address the unsafe condition on these products.

FMI: www.regulations.gov