[4910-I3-PI

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39 .•.n'

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proposing this supplemental NPRM to prevent electrical current from flowing through

fuel tank. This condition, in combination with flarrunable fuel vapors, could result in a

MOY actuator into a fuel tank, which could create a potential ignition source inside the

electrical bond resistance between the motor operated valve (ivIOV) actuators and

airplane structure for the main, ~enter, auxiliary, and horizontal stabilizer fuel tanks, as

applicable, and corrective action!if necessary. The original NPRM also required a

revision to the maintenance pro~'am to incorporate airworthiness limitation (AWL)

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No. 28-AWL-21 or AWL No. 28-AWL-27, as applicable. The original NPRM resulted

from fuel system reviews condJtcd by the manufacturer. This supplemental NPRl\1

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would revise the original NPRM by adding airplanes to the applicability, and would

require replacing Production-ins~alled laminate phenolic spacers with metallic spacers

between the fuel jettison MOV and the airplane structure, as applicable. We are

SUMMARY: We are revising an earlier proposed airworthiness directive (AD) for

certain Model 747 airplanes. The original NPRM would have required measuring the

ACTION: Supplemental notice of proposed rulemaking (NPRM); reopening of comrne

period.

AGENCY: Federal Aviation Administration (FAA), DOT.

Ainvorthiness Directives; 'I:he Boeing Company Model 747 Airplanes

fuel tank explosion and consequent loss of the airplane.

IDocket No. FAA-2008-0090; Directorate Ideotifier 2007-NM-312-ADI

RlN 2120-AA64

DATES: We must receive cO.Qllllcnts on this supplemental NPRM by [INSERT DATE

2S DAYS AFTER DATE OF PUBLICATION INTIIE FEDERAL REGISTER].
(4910·13·PI

DEPARTMENT OF TRANSPORT AnON

Federal Aviation Adminis:tnltion

I

1.4CFR Part 39

[Doc,ket No. fAA-201O-++++j Directorate Identifier 2007-Ni\'1-31!-AD]

RlN 2120·AA64

Ainvorthiness Directives; The Boeing Company Model 747 Airplanes

AGENCY: Feder.nl Aviation Administration (FAA)) DOT.

ACTION: Supplemental notice of proposed rulemaking (NPRM); rcopeni.ng of comme

period.

SUMMARY: We are revising an earlier proposed aif\"'onhiness directive (AD) for

cenain Model 747 airplanes. The original NPRM would have required measuring the

electrical bond resistance bcr""cill the motor operated valve (MOV) aClual'Or5 and

airplane structure for the main, center, auxiliary, and horizontal stabilizer fuel tanks. as

appJjcablc. and corrective action if necessary. The original NPRM also required a

revision to the maintenance prog~al11to incorporate airworthiness limitation (A WL)

No. 28-A WL-21 or AWL No. 28-A WL-27, as applicable. The original NPRM resulted

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from fuel syslem reviews, conduyed by the manufacturer. This supplemental NPRlvt

would revise the original NPRM by adding airplanes to the applicability, and would

require replacing production-installed laminate phenolic spacers with metallic spacers

between the fuel jenison MOV and the airplane structure. as applicable. We are

proposing this supplemental NPR.~I to prevent electrical current from fJawing through a

MOV actuator into a fuel tank, which could create a pOlential ignition source inside the

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fuel tank. This condition. in combination with flammable fuel vapors, could result ill a

fuel tank explosion and consequent loss of the ai.rplane. .

DATES: We must receive commbnts on this supplemental NPRM by [INSERT DATE

25 DAYS AFTER DATE OF PUBUCATION TN THE FEDERAL REGISTER).

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14910-13-1'1

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 eFR Pari 39

IDocke! No. FAA~2010-++++: Directorate Identifier 2007-N!\1-312-ADJ

RIN 2) 20-AA64

Airworthiness Directives; The Boeing Company Model 747 Airplanes

AGENCY: Federal Aviation Adminislration (FAA), DOT.

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ACTION: Supplemental notice of proposed mlernak.ing (NPRM); reopening of comme { '" 'lC/=>.c>

period.

SUMMAR Y: \Vc arc revising :m earlier proposed airworthiness directive (AD) for

certain Model 747 airplanes_ The original NPRM would have required measllring the

electrical bond resistance between the motor operated valve (MOV) aclUators .md

<lirplanc stnlcture for the main, center. auxiliary, and horizoll1al stabilizer fllel tanks, tiS

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applic:lble, and con"cctive action if necessary. The original NPRM also requir>.-"'da

revision to the maintenance program to Incorporate airworthiness llmitation (A WL)

No. 28·AWL-2J or AWL No_ 28-AWL-27, as applicable. Theorigmal NPRIv1 resulted

frolll fuel ~ystcm rcvic",,·s conducted by the manufacturer. This supplemental NPRIvl

would revise the onginal NPRM by adding airplanes to the applicability. and would

require replacing productioll-lIlstal1ed lamill3te phenolic spacers with metallic spilcers

bCl\vecn the fuel jettison MOV and the airplane structure, as applicable. ,",Veare

proposing this supplemcnl<ll NPR1vl to prevent electrical curren! from flowing through a

MOV actuaLor inio a fuel tank, which could create a potential ignition source inside the

fuel tank. This condition, in combination with flammable fuel vapors, could result in a

(tIe! t<lnkexp losion and 'consequent loss of the lIlrplane.

DATES: We must receive comments on Ihis supplemental NPRM by [INSERT DATE

25 DAYS ArTER DATE OF PUBLICATION IN THE FEDERAL HEGlSTER].

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