Summary
This document extends the period for public comment on the above-referenced NPRM. The proposed AD would require repetitive inspections of the upper and lower main wing spar cap angles for cracks and/or corrosion and installing inspection access panels. The proposed AD would also require replacing the wing spar cap angles if moderate or severe corrosion is found and applying corrosion inhibitor. The proposed AD was prompted by reports of intergranular exfoliation and corrosion of the upper and/or lower wing main spar cap angles found on the affected airplanes. We are proposing this AD to detect and correct cracks, intergranular exfoliation and corrosion in the wing main spar cap angles, which could result in reduced strength of the wing spar and the load carrying capacity of the wing. This could lead to wing failure and consequent loss of control. This extension of the comment period is necessary to assure that all interested persons have ample opportunity to present their views on the proposed requirements of the NPRM.