Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 737-8, 737-9, and 737-8200 airplanes. This proposed AD was prompted by a determination that a new airworthiness limitation is necessary to require periodic replacement of the oxygen sensor of the nitrogen generation system (NGS). This proposed AD would require revising the existing maintenance or inspection program, as applicable, to incorporate the new airworthiness limitation. The FAA is proposing this AD to address the unsafe condition on these products.