[Federal Register: June 5, 2007 (Volume 72, Number 107)]
[Proposed Rules]
[Page 30996-30998]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr05jn07-16]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2007-28348; Directorate Identifier 2007-NM-060-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800
and -900 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 737-600, -700, -700C, -800 and -900 series
airplanes. This proposed AD would require sealing the fasteners on the
front and rear spar inside the main fuel tank and on the lower panel of
the center fuel tank, inspecting the wire bundle support installation
in the equipment cooling system bays to identify the type of clamp
installed and determine whether the Teflon sleeve is installed, and
doing related corrective actions if necessary. This proposed AD results
from a design review of the fuel tank systems. We are proposing this AD
to prevent arcing at certain fuel tank fasteners, in the event of a
lightning strike or fault current event, which, in combination with
flammable fuel vapors, could result in a fuel tank explosion and
consequent loss of the airplane.
DATES: We must receive comments on this proposed AD by July 20, 2007.
[[Page 30997]]
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: Kathrine Rask, Aerospace Engineer,
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification
Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone
(425) 917-6505; 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-
28348; Directorate Identifier 2007-NM-060-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''
(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 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.
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.
Boeing determined during the SFAR 88 review that certain non-
conductive fasteners, which penetrate the main and center fuel tanks,
could be subject to lightning strikes or fault currents induced by
short circuits. During a lightning strike or fault current event,
electrical current may be conducted to those non-conductive fasteners,
which if unsealed could create arcing inside the fuel tanks. 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 737-57A1279, dated
January 24, 2007. The service bulletin describes procedures for the
following actions (depending on airplane configuration):
Sealing the fasteners on the front and rear spar inside
the main fuel tank and on the lower panel of the center fuel tank;
Inspecting the wire bundle support installation in the
equipment cooling system bays to identify the type of clamp installed
and determine whether the Teflon sleeve is installed;
Replacing any incorrect clamp with a new correct clamp;
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.
[[Page 30998]]
Costs of Compliance
There are about 1,754 airplanes of the affected design in the
worldwide fleet; of these, 645 airplanes are U.S. registered. The
following table provides the estimated costs for U.S. operators to
comply with this proposed AD, at an average hourly labor rate of $80.
Estimated Costs
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Number of
Work Average Cost per U.S.-
Action Group hours hourly airplane registered Fleet cost
labor rate airplanes
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Sealant application......................... 1 62 $80 $4,960 586 $2,906,560
2 28 80 2,240 44 98,560
3 28 80 2,240 15 33,600
Inspection.................................. 1 3 80 240 586 140,640
2 3 80 240 44 10,560
3 2 80 160 15 2,400
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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-2007-28348; Directorate Identifier 2007-NM-
060-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 Model 737-600, -700, -700C, -800 and -900
series airplanes, certificated in any category; as identified in
Boeing Alert Service Bulletin 737-57A1279, dated January 24, 2007.
Unsafe Condition
(d) This AD results from a design review of the fuel tank
systems. We are issuing this AD to prevent arcing at certain fuel
tank fasteners, in the event of a lightning strike or fault current
event, which, in combination with flammable fuel vapors, 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
(f) Within 60 months after the effective date of this AD: Seal
the fasteners on the front and rear spar inside the main fuel tank
and on the lower panel of the center fuel tank, as applicable, in
accordance with the Accomplishment Instructions of Boeing Alert
Service Bulletin 737-57A1279, dated January 24, 2007.
Inspection
(g) Within 60 months after the effective date of this AD:
Perform a general visual inspection of the wire bundle support
installation in the equipment cooling system bays to identify the
type of clamp installed, and determine whether the Teflon sleeve is
installed. Do these actions in accordance with the Accomplishment
Instructions of Boeing Alert Service Bulletin 737-57A1279, dated
January 24, 2007. Do all applicable corrective actions within 60
months after the effective date of this AD in accordance with 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.
(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. E7-10755 Filed 6-4-07; 8:45 am]
BILLING CODE 4910-13-P