Airworthiness Directives; Boeing Model 737-300, -400, and -500 Series Airplanes

[Federal Register Volume 70, Number 122 (Monday, June 27, 2005)]
[Rules and Regulations]
[Pages 36821-36823]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-12514]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2004-19533; Directorate Identifier 2004-NM-31-AD; 
Amendment 39-14164; AD 2005-13-27]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-300, -400, and -500 
Series Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain Boeing Model 737-300, -400, and -500 series airplanes. This AD 
requires repetitive inspections for cracking of the crown area of the 
fuselage skin, and corrective actions if necessary. This AD is prompted 
by a Model 737 fuselage structure test and fatigue analysis that 
indicate fuselage skin cracking could occur between 21,000 and 42,000 
total flight cycles. We are issuing this AD to detect and correct 
fatigue cracking of the fuselage skin, which could cause the fuselage 
skin to fracture and fail, and could result in rapid decompression of 
the airplane.

DATES: This AD becomes effective August 1, 2005.
    The incorporation by reference of a certain publication listed in 
the AD is approved by the Director of the Federal Register as of August 
1, 2005.

ADDRESSES: For service information identified in this AD, contact 
Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-
2207.
    Docket: The AD docket contains the proposed AD, comments, and any 
final disposition. 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 U.S. 
Department of Transportation, 400 Seventh Street SW., room PL-401, 
Washington, DC. This docket number is FAA-2004-19533; the directorate 
identifier for this docket is 2004-NM-31-AD.

FOR FURTHER INFORMATION CONTACT: Sue Lucier, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
917-6438; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION: The FAA proposed to amend 14 CFR part 39 
with an AD for certain Boeing Model 737-300, -400, and -500 series 
airplanes. That action, published in the Federal Register on November 
5, 2004 (69 FR 64534), proposed to require repetitive inspections for 
cracking of the crown area of the fuselage skin, and corrective actions 
if necessary.

Comments

    We provided the public the opportunity to participate in the 
development of this AD. We have considered the comments that have been 
submitted on the proposed AD.

Request to Incorporate Revised Repair and Preventive Modification 
Procedures

    One commenter, the airplane manufacturer, requests that the 
proposed AD be revised to include the instructions provided to airplane 
operators in Boeing Communication System Activity 1-VN5QD. This Boeing 
Communication revises the repair and preventive modification procedures 
in Boeing Special Attention Service

[[Page 36822]]

Bulletin 737-53-1234, dated June 13, 2002 (which is cited as the 
appropriate source of service information for the proposed AD). The 
revised procedures reduce the number of fasteners common to the first 
fastener row at the tear straps. The commenter states that the fastener 
size and pattern in the tear straps that are part of the procedures in 
the original issue of the service bulletin will not be consistent with 
future structural repair manual (SRM) repairs. These SRM repairs are 
currently being developed for Model 737-300, -400, and -500 series 
airplanes, with 20-inch tear strap spacing. The commenter explains that 
the fastener pattern and size difference in the SRM is being 
incorporated in an effort to maximize the ``fail safety'' of the repair 
by increasing the net area across the tear strap at the critical rows 
of the repair. The commenter points out that the procedures in the 
original issue of the service bulletin are adequate and do not contain 
an unsafe repair; however, there is a potential inconsistency between 
the service bulletin and the SRM. The commenter feels that this 
inconsistency would not represent best design practices given the 
potential number of repairs that could be required if a significant 
amount of chem-mill cracking occurs. The commenter further states that 
it is planning to revise Boeing Special Attention Service Bulletin 737-
53-1234 to incorporate the instructions in Boeing Communication System 
Activity 1-VN5QD.
    We partially agree with the commenter. We agree with the request to 
incorporate best design practices for repairs to the fuselage, because 
mandating an action with known obsolete information ultimately requires 
additional work for the industry. However, we disagree with including a 
Boeing Communication as part of the AD, because multiple sources of AD-
mandated instructions can increase the potential for misinterpretation 
and non-compliance. In addition, since the time the comments were made, 
the commenter (the airplane manufacturer) has revised the repair 
information in the service bulletin to include the information in 
Boeing Communication System Activity 1-VN5QD. We have included this 
revision of the service bulletin (Boeing Special Attention Service 
Bulletin 737-53-1234, Revision 1, dated March 31, 2005) in the final 
rule as the appropriate source of service information for accomplishing 
the AD actions. Revision 1 adds no further work to the original issue 
of the service bulletin, but incorporates the information in Boeing 
Communication System Activity 1-VN5QD. The final rule mandates the 
revised service bulletin. We have also added a new paragraph (l) to the 
final rule, which allows credit for actions done in accordance with the 
original issue of the service bulletin. We have re-identified 
subsequent paragraphs accordingly.

Request to Fix Typographical Error

    The same commenter requests that we fix the typographical error 
``appropriateaction'' in paragraph (j) of the proposed AD.
    We have changed paragraph (j) of the final rule to read 
``appropriate action'' instead of ``appropriateaction.''

Explanation of Changes Made to This AD

    We have revised paragraph (j) of the final rule to allow any crack 
in the subject area to be repaired according to data that conform to 
the airplane's type certificate and that are approved by an Authorized 
Representative for the Boeing Delegation Option Authorization 
Organization whom we have authorized to make such findings.
    We have revised paragraphs (i)(1), (i)(2)(i), and (i)(2)(ii) of the 
final rule to remove references to the notes in Part 2 and Part 3 of 
the Work Instructions in the original issue of the service bulletin. 
The notes are no longer in those parts of Revision 1 of the service 
bulletin. The information in the referenced notes is still required by 
this AD, but in Revision 1 of the service bulletin this information has 
been incorporated into the procedures of Part 2 and Part 3.

Conclusion

    We have carefully reviewed the available data, including the 
comments that have been submitted, and determined that air safety and 
the public interest require adopting the AD with the changes described 
previously. We have determined that these changes will neither increase 
the economic burden on any operator nor increase the scope of the AD.

Costs of Compliance

    There are about 579 airplanes of the affected design in the 
worldwide fleet. The following table provides the estimated costs for 
U.S. operators to comply with this proposed AD.

                                                                     Estimated Costs
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                                                                                                           Cost per
                                                                                       Average labor    airplane, per   Number of U.S.-  Fleet cost, per
                               Action                                   Work hours     rate per hour      inspection       registered       inspection
                                                                                                            cycle          airplanes          cycle
--------------------------------------------------------------------------------------------------------------------------------------------------------
Inspections........................................................              94              $65           $6,110              175       $1,069,250
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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 AD will not have federalism 
implications under Executive Order 13132. This AD will 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 this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866;
    (2) Is not a ``significant rule'' under 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 36823]]

under the criteria of the Regulatory Flexibility Act.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this 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, Incorporation by 
reference, Safety.

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
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]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive (AD):

2005-13-27 Boeing: Amendment 39-14164. Docket No. FAA-2004-19533; 
Directorate Identifier 2004-NM-31-AD.

Effective Date

    (a) This AD becomes effective August 1, 2005.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 737-300, -400, and -500 
series airplanes, certificated in any category; as identified in 
Boeing Special Attention Service Bulletin 737-53-1234, Revision 1, 
dated March 31, 2005.

Unsafe Condition

    (d) This AD was prompted by a Model 737 fuselage structure test 
and fatigue analysis that indicate fuselage skin cracking could 
occur between 21,000 and 42,000 total flight cycles. We are issuing 
this AD to detect and correct fatigue cracking of the fuselage skin, 
which could cause the fuselage skin to fracture and fail, and could 
result in rapid decompression 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.

Service Bulletin References

    (f) The term ``service bulletin,'' as used in this AD, means 
Boeing Special Attention Service Bulletin 737-53-1234, Revision 1, 
dated March 31, 2005.

Initial and Repetitive Inspections

    (g) At the later of the times specified in paragraphs (g)(1) and 
(g)(2) of this AD, perform detailed and eddy current inspections for 
cracking of the crown area of the fuselage skin in accordance with 
Part 1, including the ``Note,'' of the Work Instructions of the 
service bulletin, except as provided by paragraph (j) of this AD.
    (1) Before the accumulation of the applicable total flight 
cycles specified in the ``Threshold'' column of Table 1 of Figure 1 
of the service bulletin.
    (2) Within 4,500 flight cycles after the effective date of this 
AD.
    (h) Repeat either the detailed or eddy current inspections 
specified in paragraph (g) of this AD at the applicable intervals 
specified in paragraph (h)(1) or (h)(2) of this AD until paragraph 
(i)(1) or (i)(2) of this AD has been done, as applicable.
    (1) Repeat the detailed inspections thereafter at intervals not 
to exceed 1,200 flight cycles.
    (2) Repeat the eddy current inspections thereafter at intervals 
not to exceed 3,000 flight cycles.

Permanent or Time-Limited Repair

    (i) If any cracking is found during any inspection required by 
paragraph (g) or (h) of this AD, do the actions specified in 
paragraph (i)(1) or (i)(2) of this AD in accordance with the service 
bulletin, except as provided by paragraphs (j) and (k) of this AD.
    (1) Before further flight, do a permanent repair (including 
related investigative actions and applicable corrective actions) in 
accordance with Part 2 of the Work Instructions of the service 
bulletin. Doing a permanent repair ends the repetitive inspections 
required by paragraph (h) of this AD for the repaired area only.
    (2) Do the actions specified in paragraphs (i)(2)(i) and 
(i)(2)(ii) of this AD at the time specified in the applicable 
paragraph. Doing a time-limited repair ends the repetitive 
inspections required by paragraph (h) of this AD for the repaired 
area only.
    (i) Before further flight, do a time-limited repair (including 
related investigative actions and applicable corrective actions) in 
accordance with Part 3 of the Work Instructions of the service 
bulletin.
    (ii) At the times specified in Figure 8 of the service bulletin, 
do the related investigative and corrective actions in accordance 
with Part 3 of the Work Instructions of the service bulletin.

Contact the FAA

    (j) Where the service bulletin specifies to contact Boeing for 
appropriate action: Before further flight, repair according to a 
method approved by the Manager, Seattle Aircraft Certification 
Office (ACO), FAA; or according to data meeting the certification 
basis of the airplane approved by an Authorized Representative for 
the Boeing Delegation Option Authorization Organization who has been 
authorized by the Manager, Seattle ACO, to make those findings. For 
a repair method to be approved, the approval must specifically 
reference this AD.

No Reporting

    (k) Although the service bulletin specifies reporting certain 
information to Boeing, this AD does not require that action.

Actions Accomplished According to Previous Issue of Service Bulletin

    (l) Actions done before the effective date of this AD in 
accordance with Boeing Special Attention Service Bulletin 737-53-
1234, dated June 13, 2002, are acceptable for compliance with the 
corresponding actions required by this AD.

Alternative Methods of Compliance (AMOCs)

    (m) 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.

Material Incorporated by Reference

    (n) You must use Boeing Special Attention Service Bulletin 737-
53-1234, Revision 1, dated March 31, 2005, to perform the actions 
that are required by this AD, unless the AD specifies otherwise. The 
Director of the Federal Register approves the incorporation by 
reference of this document in accordance with 5 U.S.C. 552(a) and 1 
CFR part 51. To get copies of the service information, contact 
Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 
98124-2207. To view the AD docket, go to the Docket Management 
Facility, U.S. Department of Transportation, 400 Seventh Street SW., 
room PL-401, Nassif Building, Washington, DC. To review copies of 
the service information, go to the National Archives and Records 
Administration (NARA). For information on the availability of this 
material at the NARA, call (202) 741-6030, or go to http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

    Issued in Renton, Washington, on June 15, 2005.
Kevin M. Mullin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-12514 Filed 6-24-05; 8:45 am]
BILLING CODE 4910-13-P

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