[Federal Register Volume 69, Number 151 (Friday, August 6, 2004)]
[Proposed Rules]
[Pages 47814-47816]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-17990]



[[Page 47814]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2004-18729; Directorate Identifier 2004-NM-24-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-100 and -200B Series 
Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain Boeing Model 747-100 and -200B series airplanes. This 
proposed AD would require installing bonding clips and bonding jumpers 
from the housing of each fuel pump to airplane structure outside the 
fuel tanks. This proposed AD is prompted by the results of fuel system 
reviews conducted by the manufacturer. We are proposing this AD to 
ensure adequate electrical bonding between the housing of each fuel 
pump and airplane structure outside the fuel tanks. Inadequate 
electrical bonding, in the event of a lightning strike or pump 
electrical fault, could cause electrical arcing and ignition of fuel 
vapor in the wing fuel tank, which could result in a fuel tank 
explosion.

DATES: We must receive comments on this proposed AD by September 20, 
2004.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
     DOT Docket Web site: Go to
http://dms.dot.gov and follow the instructions for sending your 
comments electronically.
     Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility, U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, room PL-401, 
Washington, DC 20590.
     By fax: (202) 493-2251.
     Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    For service information identified in this proposed AD, contact 
Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-
2207.
    You can examine the contents of this AD docket on the Internet at 
http://dms.dot.gov, or at the Docket Management Facility, U.S. 
Department of Transportation, 400 Seventh Street, SW., room PL-401, on 
the plaza level of the Nassif Building, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Dan Kinney, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone 
(425) 917-6499; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Docket Management System (DMS)

    The FAA has implemented new procedures for maintaining AD dockets 
electronically. As of May 17, 2004, new AD actions are posted on DMS 
and assigned a docket number. We track each action and assign a 
corresponding directorate identifier. The DMS AD docket number is in 
the form ``Docket No. FAA-2004-99999.'' The Transport Airplane 
Directorate identifier is in the form ``Directorate Identifier 2004-NM-
999-AD.'' Each DMS AD docket also lists the directorate identifier 
(``Old Docket Number'') as a cross-reference for searching purposes.

Comments Invited

    We invite you to submit any written relevant data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2004-18729; 
Directorate Identifier 2004-NM-24-AD'' in the subject line of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the proposed AD. We will 
consider all comments submitted by the closing date and may amend the 
proposed AD in light of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this proposed AD. Using the search function of 
that Web site, anyone can find and read the comments in any of our 
dockets, including the name of the individual who sent the comment (or 
signed the comment on behalf of an association, business, labor union, 
etc.). You can review DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or you 
can visit http://dms.dot.gov.
    We are reviewing the writing style we currently use in regulatory 
documents. We are interested in your comments on whether the style of 
this document is clear, and your suggestions to improve the clarity of 
our communications that affect you. You can get more information about 
plain language at http://www.faa.gov/language and http://www.plainlanguage.gov.

Examining the Docket

    You can examine the AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Management Facility office 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The Docket Management Facility office (telephone (800) 647-
5227) is located on the plaza level of the Nassif Building at the DOT 
street address stated in the ADDRESSES section. Comments will be 
available in the AD docket shortly after the DMS receives them.

Discussion

    We have examined the underlying safety issues involved in recent 
fuel tank explosions on several large transport airplanes, including 
the adequacy of existing regulations, the service history of airplanes 
subject to those regulations, and existing maintenance practices for 
fuel tank systems. As a result of those findings, we issued a 
regulation titled ``Transport Airplane Fuel Tank System Design Review, 
Flammability Reduction and Maintenance and Inspection Requirements'' 
(67 FR 23086, May 7, 2001). In addition to new airworthiness standards 
for transport airplanes and new maintenance requirements, this rule 
included Special Federal Aviation Regulation No. 88 (``SFAR 88,'' 
Amendment 21-78, and subsequent Amendments 21-82 and 21-83).
    Among other actions, SFAR 88 requires certain type design (i.e., 
type certificate (TC) and supplemental type certificate (STC)) holders 
to substantiate that their fuel tank systems can prevent ignition 
sources in the fuel tanks. This requirement applies to type design 
holders for large turbine-powered transport airplanes and for 
subsequent modifications to those airplanes. It requires them to 
perform design reviews and to develop design changes and maintenance 
procedures if their designs do not meet the new fuel tank safety 
standards. As explained in the preamble to the rule, we intended to 
adopt airworthiness directives to mandate any changes found necessary 
to address unsafe conditions identified as a result of these reviews.
    In evaluating these design reviews, we have established four 
criteria intended to define the unsafe conditions

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associated with fuel tank systems that require corrective actions. The 
percentage of operating time during which fuel tanks are exposed to 
flammable conditions is one of these criteria. The other three criteria 
address the failure types under evaluation: single failures, single 
failures in combination with another latent condition(s), and in-
service failure experience. For all four criteria, the evaluations 
included consideration of previous actions taken that may mitigate the 
need for further action.
    Based on this process, we have determined that the actions 
identified in this proposed AD are necessary to reduce 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.
    As a result of fuel system reviews associated with SFAR 88, the 
airplane manufacturer determined that the electrical bonding at the 
interface of the housings for the main fuel pumps and the fuel tanks is 
not adequate on certain Boeing Model 747-100 and -200B series 
airplanes. The eight main fuel boost pumps currently rely on a bolted 
connection to provide the required low electrical resistance between 
the pump housing and the fuel tank structure. However, on the affected 
airplanes, a special corrosion protection finish used on the fuel tank 
acts as a partial insulator. Given a lightning strike or pump 
electrical fault, arcing can occur at this existing interface, which is 
inside the fuel tank. This condition, if not corrected, could result in 
ignition of fuel vapor in the fuel tanks, which could result in a fuel 
tank explosion.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 747-28A2033, 
Revision 1, dated December 18, 2003, which is divided into two parts. 
Part 1 of the service bulletin describes procedures for installing 
bonding clips and bonding jumpers from the housing of each fuel pump to 
airplane structure outside the fuel tanks, including installing 
``caution'' markers next to each pump, and measuring the resistance 
between the mounting flanges of each fuel pump and the airplane 
structure. Part 2 of the service bulletin is optional and describes 
procedures for removing existing bonding jumpers from the housing of 
each fuel pump, and applying a corrosion resistant finish. 
Accomplishing the actions specified in Part 1 of the service 
information is intended to adequately address the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to exist or develop on other airplanes 
of this same type design. Therefore, we are proposing this AD, which 
would require installing bonding clips and bonding jumpers from the 
housing of each fuel pump to airplane structure outside the fuel tanks. 
The proposed AD would require you to use Part 1 of the service 
information described previously to perform these actions.

Costs of Compliance

    This proposed AD would affect about 158 airplanes worldwide. The 
following table provides the estimated costs for U.S. operators to 
comply with this proposed AD.

                                                                     Estimated Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                          Number of U.S.-
                         Action                             Work hours     Average labor       Parts         Cost per       registered      Fleet cost
                                                                           rate per hour                     airplane        airplanes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Installation of Bonding Clips/Jumpers...................               8             $65              $0            $520              23         $11,960
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Regulatory Findings

    We have determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would not 
have a substantial direct effect on the States, on the relationship 
between the national Government and the States, or on the distribution 
of power and responsibilities among the various levels of government.
    For the reasons discussed above, I certify that the proposed 
regulation:
    1. Is not a ``significant regulatory action'' under Executive Order 
12866;
    2. Is not a ``significant rule'' under the DOT Regulatory Policies 
and Procedures (44 FR 11034, February 26, 1979); and
    3. Will not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this proposed AD. See the ADDRESSES section for a location 
to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec.  39.13  [Amended]

    2. The FAA amends Sec.  39.13 by adding the following new 
airworthiness directive (AD):

    Boeing: Docket No. FAA-2004-18729; Directorate Identifier 2004-
NM-24-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this AD action by September 20, 2004.

Affected ADs

    (b) None.
    Applicability: (c) This AD applies to Boeing Model 747-100 and -
200B series airplanes having line numbers 1 through 167 inclusive, 
certificated in any category.

Unsafe Condition

    (d) This AD was prompted by the results of fuel system reviews 
conducted by the manufacturer. We are issuing this AD to ensure 
adequate electrical bonding between the housing of each fuel pump 
and airplane structure outside the fuel tanks. Inadequate electrical 
bonding, in the event of a lightning strike or pump electrical 
fault, could cause electrical arcing and ignition of fuel vapor in 
the wing fuel tank, which could result in a fuel tank explosion.
    Compliance: (e) You are responsible for having the actions 
required by this AD performed within the compliance times specified, 
unless the actions have already been done.

Installation of Bonding Clips and Bonding Jumpers

    (f) Within 60 months after the effective date of this AD, 
install bonding clips and bonding jumpers from the housing of each 
fuel pump to airplane structure located

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outside the fuel tanks by doing all of the actions in Part 1 of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 747-
28A2033, Revision 1, dated December 18, 2003.

Actions Done in Accordance With Previous Service Bulletin Revision

    (g) Installations done before the effective date of this AD in 
accordance with Boeing Service Bulletin 747-28-2033, dated December 
15, 1971, are acceptable for compliance with the requirements of 
this AD.

Alternative Methods of Compliance (AMOCs)

    (h) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, has the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.

    Issued in Renton, Washington, on July 29, 2004.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 04-17990 Filed 8-5-04; 8:45 am]
BILLING CODE 4910-13-P