[Federal Register: December 16, 2004 (Volume 69, Number 241)]
[Proposed Rules]
[Page 75280-75282]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr16de04-18]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2004-19891; Directorate Identifier 2004-NM-136-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-300, -400, and -500
Series Airplanes Modified in Accordance With Supplemental Type
Certificate (STC) ST00127BO
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 Boeing Model 737-300, -400, and -500 series airplanes modified in
accordance with STC ST00127BO. This proposed AD would require
installation of bonding straps to the safe side harnesses of the
digital transient suppression device of the fuel quantity indicating
system. This proposed AD is prompted by the results of fuel system
reviews conducted by the STC holder. We are proposing this AD to
prevent unsafe levels of current or energy from entering the fuel tank,
due to hot short faults or threat conditions associated with the safe
side harness assembly, which could result in a fire or explosion of the
fuel tank.
DATES: We must receive comments on this proposed AD by January 31,
2005.
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
Goodrich Fuel & Utility Systems, Goodrich Corporation, 100 Panton Road,
Vergennes, Vermont 05491.
You can examine the contents of this AD docket on the Internet at
http://dms.dot.gov, or in person 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. This
docket number is FAA-2004-19891; the directorate identifier for this
docket is 2004-NM-136-AD.
FOR FURTHER INFORMATION CONTACT:
Technical information: Richard Spencer, Aerospace Engineer, Boston
Aircraft Certification Office, ANE-150, FAA, Engine and Propeller
Directorate, 12 New England Executive Park, Burlington, Massachusetts
01803; telephone (781) 238-7184; fax (781) 238-7170.
Plain language information: Marcia Walters, marcia.walters@faa.gov.
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 relevant written data, views, or
arguments regarding this proposed AD. Send your comments to an address
listed under ADDRESSES. Include ``Docket No. FAA-2004-19891;
Directorate Identifier 2004-NM-136-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
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
[[Page 75281]]
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.
As a result of fuel system reviews associated with SFAR 88, the STC
holder determined that the existing design of the safe side harness for
the digital transient suppression device (DTSD) does not incorporate a
method of positively bonding the harness shields to the airframe on
certain Boeing transport category airplanes that have been modified in
accordance with STC ST00127BO. The DTSD is designed to limit current
and energy present during external threat (lightning/electromagnetic
interference (EMI)) conditions from being introduced to the fuel
quantity indicating system (FQIS) wiring. Bonding of the shielded safe
side wire harnesses that extend from the DTSD to the fuel tank entry is
essential to ensure that any induced threats or hot short faults are
limited to safe levels. Unsafe levels of current or energy entering the
fuel tank, due to hot short faults or threat conditions associated with
the safe side harness assembly, if not corrected, could result in a
fire or explosion of the fuel tank.
Relevant Service Information
We have reviewed Goodrich Service Bulletin 737-300766-28-2,
Revision 2, dated July 28, 2004. The service bulletin describes
procedures for:
1. Installing bonding straps on each safe side harness.
2. Modifying each safe side harness connector backshell at the tank
penetrations and at the DTSDs.
3. Replacing only the backshell for all circular tank and center
tank penetrations and DTSD connections that use a short 90 degree
connector backshell.
4. Replacing the whole backshell for all rectangular wing tank
penetrations that use a long 90 degree connector backshell.
5. Installing ground bracket(s) at the wing tank penetration(s).
6. Installing a ground bracket at the center tank penetration.
7. Installing a ground bracket at wing station DTSD locations.
8. Installing a ground bracket at center tank DTSD location.
9. Installing fuel quantity warning labels of the safe side
harnesses.
10. Modifying part number labels for the safe side harness.
11. Bonding verification.
12. Ensuring each safe side harness meets the requirements for
minimum clearances from other airplane equipment.
Accomplishing the actions specified in the service information is
intended to adequately address the unsafe condition. The Goodrich
service bulletin specifies that the actions must be accomplished within
the ``applicable AD compliance period.''
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 accomplishing the actions specified in the service
information described previously.
Costs of Compliance
There are about 404 airplanes of the affected design in the
worldwide fleet. This proposed AD would affect about 2 airplanes of
U.S. registry. The proposed actions would take about 9 work hours per
airplane, at an average labor rate of $65 per work hour. For airplanes
equipped with a Cinch rectangular connector, required parts would cost
about $1,650 per airplane. For all other airplanes, required parts
would cost about $1,500 per airplane. Based on these figures, the
estimated cost of the proposed AD for U.S. operators is between $2,085
and $2,235 per airplane.
Authority for This Rulemaking
The FAA's authority to issue rules regarding aviation safety is
found in Title 49 of the United States Code. 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.
This rulemaking is promulgated under the authority described in
subtitle VII, part A, subpart III, section 44701, ``General
requirements.'' Under that section, the FAA is charged with promoting
safety 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 AD.
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 75282]]
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-2004-19891; Directorate Identifier 2004-NM-
136-AD.
Comments Due Date
(a) The Federal Aviation Administration (FAA) must receive
comments on this AD action by January 31, 2005.
Affected ADs
(b) None.
Applicability
(c) This AD applies to Boeing Model 737-300, -400, and -500
series airplanes modified in accordance with Supplemental Type
Certificate (STC) ST00127BO, certificated in any category.
Unsafe Condition
(d) This AD was prompted by the results of fuel system reviews
conducted by the STC holder. We are proposing this AD to prevent
unsafe levels of current or energy from entering the fuel tank, due
to hot short faults or threat conditions associated with the safe
side harness assembly, which could result in a fire or explosion of
the fuel tank.
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.
Modification
(f) Within 12 months after the effective date of this AD, modify
the safe side harness connectors at the tank penetrations and the
digital transient suppression devices, in accordance with the
Accomplishment Instructions of Goodrich Service Bulletin 737-300766-
28-2, Revision 2, dated July 28, 2004.
Parts Installation
(g) As of the effective date of this AD, no person may install a
safe side harness, Part Number 50357-01XX, on any airplane, unless
that safe side harness has been modified in accordance with Goodrich
Service Bulletin 737-300766-28-2, Revision 2, dated July 28, 2004.
Alternative Methods of Compliance (AMOCs)
(h) The Manager, Boston 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 December 3, 2004.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 04-27519 Filed 12-15-04; 8:45 am]
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