Summary
This document extends the comment period for the above- referenced NPRM, which proposes the adoption of a new airworthiness directive (AD) that applies to certain Boeing Model 737-600, -700, - 700C, -800, and -900 series airplanes. The NRPM would require various repetitive inspections to detect cracks along the chemically milled steps of the fuselage skin or missing or loose fasteners in the area of the preventative modification or repairs, replacement of the time- limited repair with the permanent repair if applicable, and applicable corrective actions if necessary, which would end certain repetitive inspections. The NPRM results from a fatigue test that revealed numerous cracks in the upper skin panel at the chemically milled step above the lap joint. This extension of the comment period is necessary to ensure that all interested persons have ample opportunity to submit any written relevant data, views, or arguments regarding the NPRM.