Summary
The FAA proposes to supersede an existing airworthiness directive (AD) that applies to all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. The existing AD currently requires a one-time inspection for scribe lines and cracks in the fuselage skin at certain lap joints, butt joints, external repair doublers, and other areas; and related investigative/corrective actions if necessary. This proposed AD would expand the area to be inspected and, for certain airplanes, require earlier inspections for certain inspection zones. This proposed AD results from additional detailed analysis of fuselage skin cracks adjacent to the skin lap joints on airplanes that had scribe lines; the analysis resulted in different inspection zones, thresholds and repetitive intervals, and airplane groupings. We are proposing this AD to prevent rapid decompression of the airplane due to fatigue cracks