[Federal Register Volume 69, Number 226 (Wednesday, November 24, 2004)]
[Proposed Rules]
[Pages 68268-68270]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-26031]



[[Page 68268]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2004-19682; Directorate Identifier 2004-NM-88-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800 
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 737-600, -700, -700C, and -800 series 
airplanes. This proposed AD would require inspecting/measuring the 
length of the attachment fasteners between the nacelle support fittings 
and the lower wing skin panels, and related investigative/corrective 
actions if necessary. This proposed AD is prompted by a report from the 
manufacturer that in production, during the installation of certain 
attachment fasteners for the nacelle support fittings, only one washer 
was installed instead of two. We are proposing this AD to prevent 
inadequate fastener clamp-up, which could result in cracking of the 
fastener holes, cracking along the lower wing skin panels, fuel leaking 
from the wing fuel tanks onto the engines, and possible fire.

DATES: We must receive comments on this proposed AD by January 10, 
2005.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
    <bullet> DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
    <bullet> Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
    <bullet> Mail: Docket Management Facility, U.S. Department of 
Transportation, 400 Seventh Street SW., Nassif Building, Room PL-401, 
Washington, DC 20590.
    <bullet> By fax: (202) 493-2251.
    <bullet> 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: Robert Hardwick, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
917-6457; 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-2004-19682; 
Directorate Identifier 2004-NM-88-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 website, 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.
    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 may examine the AD docket 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 received a report indicating that, during the production of 
certain Boeing Model 737-600, -700, -700C, and -800 series airplanes, 
it was discovered that certain attachment fasteners that attach the 
nacelle support fittings to the lower wing skin panels were improperly 
installed. The affected fasteners were installed during production with 
only one washer instead of two, which could cause the nut to tighten 
against the thread runout on the fastener shank rather than clamping 
the joint. This condition can be identified by checking the thread 
protrusion between the top of the nut and the end of the fastener to 
determine if the thread protrusion is outside of the limits specified 
by the manufacturer. Discrepant thread protrusion could indicate 
inadequate clamp-up between the nacelle support fittings and the lower 
wing skin panels. Adequate clamp-up compresses the components together, 
which assists in preventing cracking. Inadequate clamp-up, if not 
corrected, could result in cracking of the fastener holes, cracking 
along the lower wing skin panels, fuel leaking from the wing fuel tanks 
onto the engines, and possible fire.

Relevant Service Information

    We have reviewed Boeing Service Bulletin 737-57-1275, dated 
September 4, 2003. The service bulletin describes procedures for 
inspecting/measuring the thread protrusion of certain attachment 
fasteners between the lower wing skin panels and the nacelle support 
fittings, marking fasteners with measurements outside of the specified 
thread protrusion limits, and related investigative and corrective 
actions. For fasteners with measurements outside of

[[Page 68269]]

the specified limits, the related investigative actions include reaming 
the affected fastener holes and doing a high frequency eddy current 
inspection of the complete fastener hole stack-up for cracking. If no 
cracking is found, the corrective actions include reaming the holes to 
the next nominal diameter and installing new fasteners. If cracking is 
found, the service bulletin specifies contacting Boeing for repair 
information. For repaired areas, the service bulletin also specifies 
doing fuel leak inspections. Accomplishing the actions specified in the 
service bulletin will 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 inspecting/measuring the length of the attachment 
fasteners between the nacelle support fittings and the lower wing skin 
panels, and related investigative/corrective actions if necessary. The 
proposed AD would require you to use the service information described 
previously to perform these actions, except as discussed under 
``Differences Between the Proposed AD and Service Information.''

Differences Between the Proposed AD and Service Information

    The service bulletin states that the inspection/measurement should 
be done within 30,000 flight cycles or 30,000 flight hours from 
airplane delivery, whichever is first. For airplanes not modified by 
Supplemental Type Certificate (STC) ST00830SE, this proposed AD 
specifies doing the inspection/measurement prior to the accumulation of 
30,000 total flight cycles or 30,000 total flight hours, whichever is 
first. For airplanes modified by that STC, the proposed AD specifies 
doing the inspection/measurement prior to the accumulation of 25,000 
total flight cycles or 25,000 total flight hours, whichever is first. 
The STC is an airplane modification that installs winglets. We have 
determined that airplanes with winglets have increased wing loads, 
which could result in cracking at a lower threshold than airplanes 
without winglets.
    The service bulletin also specifies that you may contact the 
manufacturer for instructions on how to repair certain conditions, but 
this proposed AD would require you to repair those conditions in one of 
the following ways:
    <bullet> Using a method that we approve; or
    <bullet> Using data that meet the type certification basis of the 
airplane, and that have been approved by a Boeing Company Designated 
Engineering Representative who has been authorized by the FAA to make 
such findings.

Costs of Compliance

    This proposed AD would affect about 751 airplanes worldwide. The 
following table provides the estimated costs for U.S. operators to 
comply with this proposed AD.

                                                                     Estimated Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                        Number of U.S.-
                Action                    Work hours     Average labor               Parts                 Cost per        registered       Fleet cost
                                                         rate per hour                                     airplane        airplanes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Inspection/Measurement...............              12              $65   Nominal.....................            $780              302         $235,560
--------------------------------------------------------------------------------------------------------------------------------------------------------

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-2004-19682; Directorate Identifier 2004-NM-
88-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this AD action by January 10, 2005.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 737-600, -700, -700C, and -
800 series airplanes; line numbers 1 through 761 inclusive, except 
for line numbers 596, 683, 742, 749, 750, 751, 754, 755, 759, and 
760; certificated in any category;

Unsafe Condition

    (d) This AD was prompted by a report from the manufacturer that 
in production, during installation of certain attachment fasteners 
for the nacelle support fittings, only one washer was installed 
instead of two. We are issuing this AD to prevent inadequate 
fastener clamp-up, which could result in cracking of the fastener 
holes, cracking along the lower wing skin panels, fuel leaking from 
the wing fuel tanks onto the engines, and possible fire.

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.

Inspection/Measurement and Related Investigative and Corrective Actions

    (f) At the applicable time specified in paragraph (f)(1) or 
(f)(2) of this AD: Inspect/measure the length of certain attachment 
fasteners between the lower wing skin panels and the nacelle support 
fittings. Do the inspection/measurement, and all applicable

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related investigative and corrective actions, in accordance with the 
Accomplishment Instructions of Boeing Service Bulletin 737-57-1275, 
dated September 4, 2003, except as provided by paragraph (g) of this 
AD.
    (1) For airplanes modified by Supplemental Type Certificate 
(STC) ST00830SE as of the effective date of this AD: Prior to the 
accumulation of 25,000 total flight hours or 25,000 total flight 
cycles, whichever is first.
    (2) For airplanes not modified by STC ST00830SE as of the 
effective date of this AD: Prior to the accumulation of 30,000 total 
flight hours or 30,000 total flight cycles, whichever is first.
    (g) If accomplishing a corrective action as required by 
paragraph (f) of this AD, and the service bulletin specifies to 
contact Boeing for repair information: Before further flight, do the 
repair in accordance with a method approved by the Manager, Seattle 
Aircraft Certification Office (ACO), FAA; or in accordance with data 
meeting the type certification basis of the airplane approved by a 
Boeing Company Designated Engineering Representative (DER) who has 
been authorized by the Manager, Seattle ACO, to make such findings. 
For a repair method to be approved, the approval must specifically 
reference this AD.

Alternative Methods of Compliance (AMOCs)

    (h)(1) The Manager, Seattle ACO, FAA, has the authority to 
approve AMOCs for this AD, if requested using the procedures found 
in 14 CFR 39.19.
    (2) An AMOC that provides an acceptable level of safety may be 
used for any repair required by this AD, if it is approved by a 
Boeing Company DER who has been authorized by the Manager, Seattle 
ACO, to make such findings. For a repair method to be approved, the 
approval must specifically refer to this AD.

    Issued in Renton, Washington, on November 10, 2004.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 04-26031 Filed 11-23-04; 8:45 am]
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