(4910-I3-P)

DEPARTMENT OF TRANSPORT ATlON Federal Aviation Administration 14CFR Part 39 2-010- 

## D03S- (DocketNo. FAA-~-l IIII; Directorate Identifier 2009-NM-066-AD) RlN 2120-AA64 Ainvorthiness Directives; Boeing Model 747-400, 747-400D, and 747-400F Series Airplanes AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice ofproposed rulcmaking (NPRM). /305 SUMMARY: We propose to adopt anew ainvorthiness directive (AD) for Boeing Mod flTIAL G O~'E
proposed AD results from fuel system reviews conducted by the manufacturer. We are proposing this AD to prevent an electrical hot short from-asource outside the FQIS toth O<JTl~G~t16OL01 densitometer wiring from causing failure ofthe FQIS densi~ometer resistors, which coul 

# t!:,~-.J6 result in an ignition source inside the center orhorizontal stabilizer fuel tanks. An 

## ~vJ 747-400, 747-400D, and 747-400F series airplanes. This proposed AD would require installing ahot short protector (lISP) for the fuel quantity indicating system (FQIS) oft center fuel tank, and for certain airplanes, the horizontal stabilizer fuel tank. This

ignition source, incombination with flammable fuel vapors, could result in afuel tank explosion and consequent loss ofthe airplane. DATES: Wemust receive comments on this proposed AD by [insert date 45 days after date ofpublication inthe FEDERAL REGISTER]. ADDRESSES: You may send comments by any ofthe following methods:
• Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments. "

• Fax: 202-493-2251. .)-. {O(4910-I3-P]

DEPARTMENT OF TRANSPORTATION Federal Aviation Administration



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## ,,~ RIN 2120-AA64 Airworthiness Directives; Boeing Model 747-400, 747-400D, and 747-400F Series Airplanes AGENCY: Federal Avialion Administration (FAA), DOT. ACTION: Notice ofproposed rulemaking (NPRM).

result inan ignition source inside the center orhorizontal stabilizer fuel tanks. An ignition source, incombination with flammable fuel vapors, could result in afuel tank proposed AD results from 

### fuel system reviews conducted,

### by the manufacturer. We are proposing this AD to prevent an electrical hot short from a source outside the .FQISto t densitometer wiring from causing failure ofthe FQIS densitometer resistors, which coul 747-400, 747-400D, and 747-400F series airplanes. This proposed AD would require installing ahot short protector (HSP) for the fuel quantity indicating system (FQIS) oft center fueltank, and forcertain airplanes, the horizontal stabilizer 

### fuel tank. This {= SUMMARY: We propose to adopt anew airworthiness directive (AD) for Boeing Mod 

## r <: G 14CFR Part 39 IDocket No. FAA-2009-1 I r I I; Directorate Identifier 2009-NM-866-AD]

explosion and consequent loss ofthe airplane. I<mALSISIG DATES: We mllstreceive comments on this proposed AD by [insert date 45 days after m. dale ofpublication inthe FEDERAL REGISTER]. ADDRESSES: You may send comments by any ofthe following methods:
• Federal eRulemaking Portal: Go to http://W\vw.regulations.gov. Follow the 

### , instructions for submitting comments. ~
• Fax: 202493-2251.

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