[Federal Register Volume 72, Number 107 (Tuesday, June 5, 2007)]
[Proposed Rules]
[Pages 30999-31000]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-10760]



[[Page 30999]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-28349; Directorate Identifier 2007-NM-025-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-100B SUD, 747-200B, 
747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, and 747SP 
Series Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (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 747-100B SUD, 747-200B, 747-200C, 747-200F, 
747-300, 747-400, 747-400D, 747-400F, and 747SP series airplanes. This 
proposed AD would require reconfiguring the clamps of certain wire 
bundles and applying insulating sealant to certain fasteners inside the 
fuel tanks. This proposed AD results from fuel system reviews conducted 
by the manufacturer. We are proposing this AD to prevent arcing inside 
the fuel tanks in the event of a lightning strike or high-powered short 
circuit, which could result in a fuel tank explosion or fire.

DATES: We must receive comments on this proposed AD by July 20, 2007.

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.
     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.
    Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for the service information identified in this 
proposed AD.

FOR FURTHER INFORMATION CONTACT: Sulmo Mariano, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone 
(425) 917-6501; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to submit any relevant written data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed in the ADDRESSES section. Include the docket number ``FAA-2007-
28349; Directorate Identifier 2007-NM-025-AD'' at the beginning 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 received 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 may review DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or you 
may visit http://dms.dot.gov.

Examining the Docket

    You may 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 Docket Management System 
receives them.

Discussion

    The FAA has examined the underlying safety issues involved in 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'' 
(66 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 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 a 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.
    We have determined that the actions identified in this 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.
    We have received a report indicating that a certain type of 
fastener used in the fuel tank walls of Model 747 airplanes is 
insufficiently bonded to the airplane structure. Further, these 
fasteners do not have sufficient electrical insulation applied inside 
the fuel tanks to prevent arcing in the event of a lightning strike or 
high-powered short circuit. This condition, if not corrected, could 
result in a fuel tank explosion or fire.

[[Page 31000]]

Relevant Service Information

    We have reviewed Boeing Special Attention Service Bulletin 747-57-
2326, dated January 4, 2007, which describes procedures for applying 
insulating sealant to certain fasteners inside the main fuel tanks.
    We have reviewed Boeing Special Attention Service Bulletin 747-57-
2327, Revision 1, dated July 10, 2006, which describes procedures for 
reconfiguring the clamps of certain wire bundles by wrapping additional 
Teflon sleeving around the wire bundles, installing new, larger clamps, 
and sealing the ends of certain fasteners inside the auxiliary fuel 
tank, main fuel tanks, and surge tanks.
    Accomplishing the actions specified in 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. For this reason, we are proposing this AD, 
which would require accomplishing the actions specified in the service 
information described previously.

Costs of Compliance

    There are about 707 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 107 airplanes of 
U.S. registry. Depending on airplane configuration, the proposed 
actions would take between 106 and 448 work hours per airplane, at an 
average labor rate of $80 per work hour. Required parts would cost 
between $430 and $2,074 per airplane. Based on these figures, the 
estimated cost of the proposed AD for U.S. operators is between $8,910 
and $37,914 per airplane, or up to $4,056,798 for all airplanes.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
subtitle VII, part A, subpart III, section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

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 and placed it in the AD docket. 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 Federal Aviation Administration (FAA) amends Sec.  39.13 by 
adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2007-28349; Directorate Identifier 2007-NM-
025-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by July 20, 
2007.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 747-100B SUD, 747-200B, 747-
200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, and 747SP 
series airplanes, certificated in any category; as identified in 
Boeing Special Attention Service Bulletin 747-57-2327, Revision 1, 
dated July 10, 2006; and Boeing Special Attention Service Bulletin 
747-57-2326, dated January 4, 2007.

Unsafe Condition

    (d) This AD results from fuel system reviews conducted by the 
manufacturer. We are issuing this AD to prevent arcing inside the 
fuel tanks in the event of a lightning strike or high-powered short 
circuit, which could result in a fuel tank explosion or fire.

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.

Change and Seal

    (f) Within 60 months after the effective date of this AD, do the 
actions required by paragraphs (f)(1) and (f)(2) of this AD.
    (1) Reconfigure the wire bundle clamps and seal the ends of 
certain fasteners inside the auxiliary fuel tank, main fuel tanks, 
and surge fuel tanks; in accordance with the Accomplishment 
Instructions of Boeing Special Attention Service Bulletin 747-57-
2327, Revision 1, dated July 10, 2006.
    (2) Seal the ends of certain fasteners inside the main fuel 
tanks, in accordance with the Accomplishment Instructions of Boeing 
Special Attention Service Bulletin 747-57-2326, dated January 4, 
2007.

Alternative Methods of Compliance (AMOCs)

    (g)(1) 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.
    (2) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Before using any approved AMOC on any airplane to which the AMOC 
applies, notify your appropriate principal inspector (PI) in the FAA 
Flight Standards District Office (FSDO), or lacking a PI, your local 
FSDO.

    Issued in Renton, Washington, on May 25, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E7-10760 Filed 6-4-07; 8:45 am]
BILLING CODE 4910-13-P