Action
Notice of proposed rulemaking (NPRM).
Summary
We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD would require installing an automatic shutoff system for the center and auxiliary tank fuel boost pumps, as applicable, and installing a placard in the airplane flight deck if necessary; replacing the P5-2 fuel system module assembly; and installing the un-commanded on (UCO) protection system for the center and auxiliary tank fuel boost pumps, as applicable. This proposed AD would also require revisions to the Limitations and Normal Procedures sections of the airplane flight manual to advise the flightcrew of certain operating restrictions for airplanes equipped with an automatic shutoff system. This proposed AD would also require revising the maintenance program by incorporating new airworthiness limitations for fuel tank systems to satisfy Special Federal Aviation Regulation No. 88 requirements. This proposed AD was prompted by fuel system reviews conducted by the manufacturer. We are proposing this AD to prevent operation of the center and auxiliary tank fuel boost pumps with continuous low pressure, which could lead to friction sparks or overheating in the fuel pump inlet that could create a potential ignition source inside the center and auxiliary fuel tanks. These conditions, in combination with flammable fuel vapors, could result in a fuel tank explosion and consequent loss of the airplane.