[Federal Register: December 20, 2005 (Volume 70, Number 243)]
[Proposed Rules]
[Page 75428-75430]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr20de05-25]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2005-23357; Directorate Identifier 2005-NM-207-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 777-200 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 777-200 series airplanes. This proposed AD
would require installing a new washer between the lower wing surface
and the jam nut of the sump drain valve assembly. This proposed AD
results from fuel system reviews conducted by the manufacturer. We are
proposing this AD to prevent energy from a lightning strike on the
bushing for the sump drain valve from arcing to the inside of the
center fuel tank wall, which could create an ignition source in the
fuel tank and result in a fuel tank explosion.
DATES: We must receive comments on this proposed AD by February 3,
2006.
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
[[Page 75429]]
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: Margaret Langsted, Aerospace Engineer,
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification
Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone
(425) 917-6500; 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-2005-
23357; Directorate Identifier 2005-NM-207-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
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 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 failure 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 small gaps may be present
between the bushing of the sump drain valve and the lower wing surface
in the center fuel tank, on certain Boeing Model 777-200 series
airplanes. If a lightning strike occurs on the bushing, arcs can go
across the small gaps between the bushing and the lower wing surface,
and into the inside of the fuel tank wall. The bushing does not have an
engineered bond path to the wing surface. In addition, the layer of
sealant between the bushing and the inner surface of the fuel tank
could be too thin to contain the energy in the arcs. This condition, if
not corrected, could create an ignition source in the center fuel tank
and result in a fuel tank explosion.
Relevant Service Information
We have reviewed Boeing Special Attention Service Bulletin 777-28-
0045, dated September 1, 2005. The service bulletin describes
procedures for installing a new washer between the lower wing surface
and the jam nut of the sump drain valve assembly. 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 88 airplanes of the affected design in the
worldwide fleet. This proposed AD would affect about 22 airplanes of
U.S. registry. The proposed actions would take about 4 work hours per
airplane, at an average labor rate of $65 per work hour. Required parts
would cost about $360 per airplane. Based on these figures, the
estimated cost of the proposed AD for U.S. operators is $13,640, or
$620 per airplane.
Authority for This Rulemaking
Title 49 of the United States Code specifies the FAA's authority to
issue
[[Page 75430]]
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-2005-23357; Directorate Identifier 2005-
NM-207-AD.
Comments Due Date
(a) The FAA must receive comments on this AD action by February
3, 2006.
Affected ADs
(b) None.
Applicability
(c) This AD applies to Boeing Model 777-200 series airplanes,
certificated in any category; as identified in Boeing Special
Attention Service Bulletin 777-28-0045, dated September 1, 2005.
Unsafe Condition
(d) This AD results from fuel system reviews conducted by the
manufacturer. We are issuing this AD to prevent energy from a
lightning strike on the bushing for the sump drain valve from arcing
to the inside of the center fuel tank wall, which could create an
ignition source in the fuel tank and 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
(f) Within 60 months after the effective date of this AD,
install a new washer between the lower wing surface and the jam nut
of the sump drain valve assembly in both wings, in accordance with
the Accomplishment Instructions of Boeing Special Attention Service
Bulletin 777-28-0045, dated September 1, 2005.
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) 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 December 13, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 05-24243 Filed 12-19-05; 8:45 am]
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