

[Federal Register: December 6, 2007 (Volume 72, Number 234)]
[Proposed Rules]               
[Page 68764-68766]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr06de07-11]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-0289; Directorate Identifier 2007-NM-208-AD]
RIN 2120-AA64

 
Airworthiness Directives; Boeing Model 757 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 757 series airplanes. This proposed AD would 
require sealing the fasteners on the front and rear spars inside the 
left and right main fuel tanks and on the lower panel of the center 
fuel tank. This proposed AD would also require inspections of the wire 
bundle support installations to verify if certain clamps are installed 
and if Teflon sleeving covers the wire bundles inside the left and 
right equipment cooling system bays, on the left and right rear spars, 
and on the left and right front spars; and corrective actions if 
necessary. This proposed AD results from a fuel system review conducted 
by the manufacturer. We are proposing this AD to prevent improperly 
sealed fasteners in the main and center fuel tanks from becoming an 
ignition source, in the event of a fault current, which could result in 
a fuel tank explosion and consequent loss of the airplane.

DATES: We must receive comments on this proposed AD by January 22, 
2008.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov.
 Follow the instructions for submitting comments.

     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays.
    For service information identified in this AD, contact Boeing 
Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov
; or in person at the Docket Management Facility 

between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Office (telephone 800-647-5527) is in the 
ADDRESSES section. Comments will be available in the AD docket shortly 
after receipt.

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 send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2007-0289; 
Directorate Identifier 2007-NM-208-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will

[[Page 68765]]

consider all comments received by the closing date and may amend this 
proposed AD because of those comments.
    We will post all comments we receive, without change, to http://www.regulations.gov
, including any personal information you provide. We 

will also post a report summarizing each substantive verbal contact we 
receive about this proposed AD.

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 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.
    Boeing has found that it is possible for some fuel tank fasteners, 
in the event of a fault current, to become an ignition source on Boeing 
Model 757 series airplanes. This condition, if not corrected, could 
result in a fuel tank explosion and consequent loss of the airplane.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 757-57A0064, dated 
July 16, 2007. The service bulletin describes procedures for sealing 
the fasteners on the front and rear spars inside the left and right 
main fuel tanks and sealing the fasteners on the lower panel of the 
center fuel tank. The service bulletin also describes procedures for 
doing general visual inspections of the wire bundle support 
installations to verify if certain full cushion clamps are installed 
and to confirm if the wire bundles are covered in Teflon sleeving at 
the following locations: Inside the left and right equipment cooling 
system bays, on the left and right rear spars, and on the left and 
right front spars. The service bulletin also describes procedures for 
doing corrective actions if necessary, which include replacing any 
incorrect clamps with certain full cushion clamps and installing any 
missing Teflon sleeving. 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, except as discussed under 
``Difference between the Proposed AD and Service Bulletin.''

Difference Between the Proposed AD and Service Bulletin

    The compliance table in paragraph 1.E. of the service bulletin 
recommends accomplishing the corrective actions (clamp replacement and 
installation of Teflon sleeving) within 5 years of the date on the 
service bulletin. This AD, however, would require accomplishing the 
corrective actions, if necessary, before further flight after 
accomplishing the inspections. We have coordinated this difference with 
Boeing.

Costs of Compliance

    There are about 1,049 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 539 airplanes of 
U.S. registry. The proposed actions would take up to 545 work hours per 
airplane depending on the airplane configuration, at an average labor 
rate of $80 per work hour. Required parts would cost about $325 per 
airplane. Based on these figures, the estimated cost of the proposed AD 
for U.S. operators is up to $23,675,575, or up to $43,925 per airplane.

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

[[Page 68766]]

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-2007-0289; Directorate Identifier 2007-NM-
208-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by January 
22, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 757-200, -200CB, -200PF, and 
-300 series airplanes, certificated in any category; as identified 
in Boeing Alert Service Bulletin 757-57A0064, dated July 16, 2007.

Unsafe Condition

    (d) This AD results from a fuel system review conducted by the 
manufacturer. We are issuing this AD to prevent improperly sealed 
fasteners in the main and center fuel tanks from becoming an 
ignition source, in the event of a fault current, which could result 
in a fuel tank explosion 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 Sealing and Inspections

    (f) Within 60 months after the effective date of this AD, seal 
the applicable fasteners and do the general visual inspections of 
the wire bundle support installations, and do all the applicable 
corrective actions before further flight, by accomplishing all of 
the applicable actions specified in the Accomplishment Instructions 
of Boeing Alert Service Bulletin 757-57A0064, dated July 16, 2007.

Alternative Methods of Compliance (AMOCs)

    (g)(1) The Manager, Seattle Aircraft Certification Office, 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 November 23, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E7-23639 Filed 12-5-07; 8:45 am]

BILLING CODE 4910-13-P
