Summary
We are revising an earlier proposed airworthiness directive (AD) for certain The Boeing Company Model 737-200, -200C, -300, -400, and -500 series airplanes. That NPRM proposed to require inspections for cracking and corrosion under the number 3 very high frequency (VHF) antenna, and corrective actions if necessary; and, for certain airplanes, replacing bonded skin panels with solid skin panels if not previously accomplished. That NPRM was prompted by reports of cracks in the skin and surrounding structure under the number 3 VHF antenna on the lower external surface of the airplane at buttock line 0.0, aft of the main landing gear wheel well. This action revises that NPRM by adding an optional preventive modification, which would terminate the inspection requirements for certain airplanes; changing certain repairs; and adding inspections. We are proposing this supplemental NPRM to detect and correct cracks and corrosion of the skin and surrounding structure under the number 3 VHF antenna, which could result in separation of the antenna from the airplane, and rapid depressurization of the airplane. Since these actions impose an additional burden over that proposed in the original NPRM, we are reopening the comment period to allow the public the chance to comment on these proposed changes.