Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing Model 727-200 series airplanes. This proposed AD would require deactivation of auxiliary fuel tank systems installed in accordance with Supplemental Type Certificate (STC) SA1350NM. This proposed AD results from fuel tank system reviews conducted by the manufacturer that identified potential unsafe conditions for which the manufacturer has not provided corrective actions. We are proposing this AD to prevent the potential of ignition sources inside fuel tanks, which, in combination with flammable fuel vapors, could result in fuel tank explosions and consequent loss of the airplane.