[Federal Register Volume 72, Number 82 (Monday, April 30, 2007)]
[Proposed Rules]
[Pages 21166-21169]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-8175]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-28035; Directorate Identifier 2006-NM-293-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 767 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 767 airplanes. This proposed AD would require 
sealing certain fasteners and stiffeners in the fuel tank, and changing 
certain wire bundle clamp configurations on the fuel

[[Page 21167]]

tank walls. This proposed AD results from fuel system reviews conducted 
by the manufacturer. We are proposing this AD to prevent possible 
ignition sources in the auxiliary fuel tank, main fuel tanks, and surge 
tanks caused by a wiring short or lightning strike, which could result 
in fuel tank explosions and consequent loss of the airplane.

DATES: We must receive comments on this proposed AD by June 14, 2007.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
    <bullet> DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
    <bullet> Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
    <bullet> Mail: Docket Management Facility, U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, room PL-401, 
Washington, DC 20590.
    <bullet> Fax: (202) 493-2251.
    <bullet> 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: Judy Coyle, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone 
(425) 917-6497; 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-
28035; Directorate Identifier 2006-NM-293-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.
    A safety assessment by Boeing identified a certain fastener type in 
the fuel tank walls that has an insufficient bond to the structure. 
These fasteners can be a path for electrical energy to enter the fuel 
tank if a wiring short occurs in a wire bundle installed along the fuel 
tank boundary structure, or if lightning strikes a wing surface. If 
energy from a wiring short or lightning strike goes through these 
fasteners, arcing can occur at the ends of the fasteners in the fuel 
tank. The ends of the fasteners in the fuel tank do not have sufficient 
electrical insulation to contain the energy from the arcs. This 
condition, if not corrected, could result in a potential ignition 
source inside a fuel tank.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 767-57A0100, dated 
August 21, 2006. The service bulletin describes procedures for sealing 
the ends of the fasteners on the brackets that hold the vortex 
generators, and, for certain airplanes, sealing the ends of fasteners 
on certain stiffeners on the rear spar.
    We have also reviewed Boeing Alert Service Bulletin 767-57A0102, 
dated October 25, 2006. The service bulletin describes procedures for 
changing the wire bundle clamp configurations at specified locations on 
the fuel tank walls, and sealing the fasteners and certain stiffeners 
at specified locations in the fuel tank.
    Accomplishing the actions specified in the service information is 
intended to adequately address the unsafe condition.

[[Page 21168]]

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 925 airplanes of the affected design in the 
worldwide fleet. The following table provides the estimated costs for 
U.S. operators to comply with this proposed AD. There are no U.S.-
registered airplanes in Group 3 of Service Bulletin 767-57A0102. The 
average labor rate is $80 per work hour.

                                                 Estimated Costs
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                                                                                         Number of
                                                                             Cost per      U.S.-
         Service bulletin              Group      Work hours     Parts       airplane    registered   Fleet cost
                                                                                         airplanes
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767-57A0100.......................            1            6        (\1\)         $480          341     $163,680
                                              2          114        (\1\)        9,120           21      191,520
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767-57A0102.......................            1          246       $1,632       21,312          341    7,267,392
                                              2          874        1,304       71,224           21    1,495,704
                                              3           24          338        2,258            0            0
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(1) Minimal.

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-2007-28035; Directorate Identifier 2006-NM-
293-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by June 14, 
2007.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Model 767-200, -300, -300F, and -400ER 
series airplanes; certificated in any category; as identified in 
Boeing Alert Service Bulletin 767-57A0100, dated August 21, 2006; 
and Boeing Alert Service Bulletin 767-57A0102, dated October 25, 
2006.

Unsafe Condition

    (d) This AD results from fuel system reviews conducted by the 
manufacturer. We are issuing this AD to prevent possible ignition 
sources in the auxiliary fuel tank, main fuel tanks, and surge tanks 
caused by a wiring short or lightning strike, which could result in 
fuel tank explosions and consequent loss of the airplane.

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.

Fastener Sealant Application

    (f) For airplanes identified in Boeing Alert Service Bulletin 
767-57A0100, dated August 21, 2006: Within 60 months after the 
effective date of this AD, seal the ends of the fasteners on the 
brackets that hold the vortex generators, and seal the ends of the 
fasteners on certain stiffeners on the rear spar, as applicable. Do 
the actions in accordance with the Accomplishment Instructions of 
the service bulletin.

Wire Bundle Sleeve and Clamp Installation and Fastener Sealant 
Application

    (g) For airplanes identified in Boeing Alert Service Bulletin 
767-57A0102, dated October 25, 2006: Within 60 months after the 
effective date of this AD, change the wire bundle clamp 
configurations at specified locations on the fuel tank walls, and 
seal the fasteners and certain stiffeners at specified locations on 
the fuel tank. Do the actions in accordance with the Accomplishment 
Instructions of the service bulletin.

Alternative Methods of Compliance (AMOCs)

    (h)(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.

[[Page 21169]]

    (2) Before using any AMOC approved in accordance with Sec.  
39.19 on any airplane to which the AMOC applies, notify the 
appropriate principal inspector in the FAA Flight Standards 
Certificate Holding District Office.

    Issued in Renton, Washington, on April 17, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E7-8175 Filed 4-27-07; 8:45 am]
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