[Federal Register: August 6, 2004 (Volume 69, Number 151)]
[Proposed Rules]
[Page 47814-47816]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr06au04-21]
[[Page 47814]]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2004-18729; Directorate Identifier 2004-NM-24-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 747-100 and -200B Series
Airplanes
AGENCY: Federal Aviation Administration (FAA), 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 747-100 and -200B series airplanes. This
proposed AD would require installing bonding clips and bonding jumpers
from the housing of each fuel pump to airplane structure outside the
fuel tanks. This proposed AD is prompted by the results of fuel system
reviews conducted by the manufacturer. We are proposing this AD to
ensure adequate electrical bonding between the housing of each fuel
pump and airplane structure outside the fuel tanks. Inadequate
electrical bonding, in the event of a lightning strike or pump
electrical fault, could cause electrical arcing and ignition of fuel
vapor in the wing fuel tank, which could result in a fuel tank
explosion.
DATES: We must receive comments on this proposed AD by September 20,
2004.
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.
By 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.
For service information identified in this proposed AD, contact
Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-
2207.
You can examine the contents of this AD docket on the Internet at
http://dms.dot.gov, or at the Docket Management Facility, U.S.
Department of Transportation, 400 Seventh Street, SW., room PL-401, on
the plaza level of the Nassif Building, Washington, DC.
FOR FURTHER INFORMATION CONTACT: Dan Kinney, Aerospace Engineer,
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification
Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone
(425) 917-6499; fax (425) 917-6590.
SUPPLEMENTARY INFORMATION:
Docket Management System (DMS)
The FAA has implemented new procedures for maintaining AD dockets
electronically. As of May 17, 2004, new AD actions are posted on DMS
and assigned a docket number. We track each action and assign a
corresponding directorate identifier. The DMS AD docket number is in
the form ``Docket No. FAA-2004-99999.'' The Transport Airplane
Directorate identifier is in the form ``Directorate Identifier 2004-NM-
999-AD.'' Each DMS AD docket also lists the directorate identifier
(``Old Docket Number'') as a cross-reference for searching purposes.
Comments Invited
We invite you to submit any written relevant data, views, or
arguments regarding this proposed AD. Send your comments to an address
listed under ADDRESSES. Include ``Docket No. FAA-2004-18729;
Directorate Identifier 2004-NM-24-AD'' in the subject line 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 submitted 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 can review DOT's complete Privacy Act Statement in the
Federal Register published on April 11, 2000 (65 FR 19477-78), or you
can visit http://dms.dot.gov.
We are reviewing the writing style we currently use in regulatory
documents. We are interested in your comments on whether the style of
this document is clear, and your suggestions to improve the clarity of
our communications that affect you. You can get more information about
plain language at http://www.faa.gov/language and http://www.plainlanguage.gov.Examining
the Docket
You can 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 DMS receives them.
Discussion
We have 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
[[Page 47815]]
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.
Based on this process, 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.
As a result of fuel system reviews associated with SFAR 88, the
airplane manufacturer determined that the electrical bonding at the
interface of the housings for the main fuel pumps and the fuel tanks is
not adequate on certain Boeing Model 747-100 and -200B series
airplanes. The eight main fuel boost pumps currently rely on a bolted
connection to provide the required low electrical resistance between
the pump housing and the fuel tank structure. However, on the affected
airplanes, a special corrosion protection finish used on the fuel tank
acts as a partial insulator. Given a lightning strike or pump
electrical fault, arcing can occur at this existing interface, which is
inside the fuel tank. This condition, if not corrected, could result in
ignition of fuel vapor in the fuel tanks, which could result in a fuel
tank explosion.
Relevant Service Information
We have reviewed Boeing Alert Service Bulletin 747-28A2033,
Revision 1, dated December 18, 2003, which is divided into two parts.
Part 1 of the service bulletin describes procedures for installing
bonding clips and bonding jumpers from the housing of each fuel pump to
airplane structure outside the fuel tanks, including installing
``caution'' markers next to each pump, and measuring the resistance
between the mounting flanges of each fuel pump and the airplane
structure. Part 2 of the service bulletin is optional and describes
procedures for removing existing bonding jumpers from the housing of
each fuel pump, and applying a corrosion resistant finish.
Accomplishing the actions specified in Part 1 of 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. Therefore, we are proposing this AD, which
would require installing bonding clips and bonding jumpers from the
housing of each fuel pump to airplane structure outside the fuel tanks.
The proposed AD would require you to use Part 1 of the service
information described previously to perform these actions.
Costs of Compliance
This proposed AD would affect about 158 airplanes worldwide. The
following table provides the estimated costs for U.S. operators to
comply with this proposed AD.
Estimated Costs
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Number of U.S.-
Action Work hours Average labor Parts Cost per registered Fleet cost
rate per hour airplane airplanes
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Installation of Bonding Clips/Jumpers................... 8 $65 $0 $520 23 $11,960
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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. 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 FAA amends Sec. 39.13 by adding the following new
airworthiness directive (AD):
Boeing: Docket No. FAA-2004-18729; Directorate Identifier 2004-
NM-24-AD.
Comments Due Date
(a) The Federal Aviation Administration (FAA) must receive
comments on this AD action by September 20, 2004.
Affected ADs
(b) None.
Applicability: (c) This AD applies to Boeing Model 747-100 and -
200B series airplanes having line numbers 1 through 167 inclusive,
certificated in any category.
Unsafe Condition
(d) This AD was prompted by the results of fuel system reviews
conducted by the manufacturer. We are issuing this AD to ensure
adequate electrical bonding between the housing of each fuel pump
and airplane structure outside the fuel tanks. Inadequate electrical
bonding, in the event of a lightning strike or pump electrical
fault, could cause electrical arcing and ignition of fuel vapor in
the wing fuel tank, which could 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 of Bonding Clips and Bonding Jumpers
(f) Within 60 months after the effective date of this AD,
install bonding clips and bonding jumpers from the housing of each
fuel pump to airplane structure located
[[Page 47816]]
outside the fuel tanks by doing all of the actions in Part 1 of the
Accomplishment Instructions of Boeing Alert Service Bulletin 747-
28A2033, Revision 1, dated December 18, 2003.
Actions Done in Accordance With Previous Service Bulletin Revision
(g) Installations done before the effective date of this AD in
accordance with Boeing Service Bulletin 747-28-2033, dated December
15, 1971, are acceptable for compliance with the requirements of
this AD.
Alternative Methods of Compliance (AMOCs)
(h) 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.
Issued in Renton, Washington, on July 29, 2004.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 04-17990 Filed 8-5-04; 8:45 am]
BILLING CODE 4910-13-P