Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800, and -900 Series Airplanes

Résumé

The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes. This proposed AD 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. This proposed AD results from a fatigue test that revealed numerous cracks in the upper skin panel at the chemically milled step above the lap joint. We are proposing this AD to detect and correct such fatigue-related cracks, which could result in the crack tips continuing to turn and grow to the point where the skin bay flaps open, causing decompression of the airplane.