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[Federal Register Volume 77, Number 117 (Monday, June 18, 2012)]
[Rules and Regulations]
[Pages 36134-36137]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-14377]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2011-1254; Directorate Identifier 2010-NM-178-AD; 
Amendment 39-17083; AD 2012-12-04]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are superseding an existing airworthiness directive (AD) 
for certain The Boeing Company Model 737-300, -400, and -500 series 
airplanes. That AD currently requires repetitive external detailed 
inspections or non-destructive inspections to detect cracks in the 
fuselage skin along the chem-mill steps at stringers S-1 and S-2R, 
between station (STA) 400 and STA 460, and repair if necessary. This 
new AD adds inspections for cracking in additional fuselage skin 
locations, and repair if necessary. This new AD also reduces the 
inspection thresholds and repetitive intervals for certain airplanes. 
This AD was prompted by reports of additional crack findings of the 
fuselage skin at the chem-mill steps. We are issuing this AD to detect 
and correct fatigue cracking of the fuselage skin panels at the chem-
mill steps, which could result in sudden fracture and failure of the 
fuselage skin panels, and consequent rapid decompression of the 
airplane.

DATES: This AD is effective July 23, 2012.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in the AD as of July 23, 
2012.

ADDRESSES: For service information identified in this AD, contact 
Boeing Commercial Airplanes, Attention: Data & Services Management, 
P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 206-
544-5000, extension 1; fax 206-766-5680; Internet https://www.myboeingfleet.com. You may review copies of the referenced service 
information at the FAA, Transport Airplane Directorate, 1601 Lind 
Avenue SW., Renton, Washington. For information on the availability of 
this material at the FAA, call 425-227-1221.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov; or in person at the Docket Management Facility 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this AD, the regulatory evaluation, 
any comments received, and other information. The address for the 
Docket Office (phone: 800-647-5527) is Document Management Facility, 
U.S. Department of Transportation, Docket Operations, M-30, West 
Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE., 
Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Wayne Lockett, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue SW., Renton, Washington 98057-3356; phone: 425-917-
6447; fax: 425-917-6590; email: wayne.lockett@faa.gov.

SUPPLEMENTARY INFORMATION: 

Discussion

    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 
part 39 to supersede AD 2008-19-03, Amendment 39-15670 (73 FR 56958, 
October 1, 2008). That AD applies to the specified products. The NPRM 
published in the Federal Register on November 28, 2011 (76 FR 72853). 
That NPRM proposed to continue to require repetitive external detailed 
inspections or non-destructive inspections to detect cracks in the 
fuselage skin along the chem-mill steps at stringers S-1 and S-2R, 
between station (STA) 400 and STA 460, and repair if necessary. That 
NPRM also proposed to add inspections for cracking in additional 
fuselage skin locations, and repair if necessary. That NPRM also 
proposed to reduce the inspection thresholds and repetitive intervals 
for certain airplanes.

Comments

    We gave the public the opportunity to participate in developing 
this AD. The following presents the comments received on the proposal 
(76 FR 72853, November 28, 2011) and the FAA's response to each 
comment.

Support for the NPRM (76 FR 72853, November 28, 2011)

    The National Transportation Board supports the NPRM (76 FR 72853, 
November 28, 2011).

Request To Revise Paragraph (j) of the NPRM (76 FR 72853, November 28, 
2011)

    Boeing asked that we include Boeing Alert Service Bulletin 737-
53A1293, Revision 1, dated July 7, 2010, in the exception to the 
service bulletin

[[Page 36135]]

specified in paragraph (j) of the NPRM (76 FR 72853, November 28, 
2011). (Paragraph (j) of the NPRM is identified as paragraph (j)(1) in 
this final rule.) Boeing stated that the compliance times in paragraph 
1.E. ``Compliance'' of Boeing Service Bulletin 737-53A1293, Revision 2, 
dated August 10, 2011, are based on the release date of Boeing Alert 
Service Bulletin 737-53A1293, Revision 1, dated July 7, 2010. Boeing 
added that paragraph (j) of the NPRM should be changed to reference 
Boeing Alert Service Bulletin 737-53A1293, Revision 1, dated July 7, 
2010.
    We agree with the commenter's request for the reason provided. We 
have changed paragraph (j)(1) of this AD accordingly.

Request To Clarify the Language in Paragraph (k) of the NPRM (76 FR 
72853, November 28, 2011)

    Boeing asked that the language specified in paragraph (k) of the 
NPRM (76 FR 72853, November 28, 2011) be clarified. (Paragraph (k) of 
the NPRM is identified as paragraph (j)(2) in this final rule.) Boeing 
stated that the intent of paragraph (k) of the NPRM is ``to specify an 
exception to the compliance time for accomplishing the next service 
bulletin inspection, being the effective date of the AD, for the 
condition addressed by the paragraph.'' Boeing added that the language 
does not clearly describe that it is an exception to the compliance 
time; rather, it could be interpreted as an exception to the condition.
    We agree to provide clarification. Paragraph (j)(2) of this AD is 
an exception to the conditions, and is provided to establish a date 
from which to determine if an inspection has been previously 
accomplished. Therefore, we have made no change to the AD in this 
regard.

Change to Final Rule

    This final rule has been changed to include an optional 
modification of the chem-milled steps at any location identified in 
Boeing Service Bulletin 737-53A1293, Revision 2, dated August 10, 2011, 
which would eliminate the need for the repetitive inspections required 
by paragraph (g) of this AD. We have determined that we can better 
ensure long-term continued operational safety by including this 
modification. Therefore, we have added a new paragraph (i) to this AD 
to include this modification, and reidentified subsequent paragraphs 
accordingly. In addition, we have indicated in the Costs of Compliance 
section of this AD that we do not have data regarding the cost of the 
optional terminating action.

Conclusion

    We reviewed the relevant data, considered the comments received, 
and determined that air safety and the public interest require adopting 
the AD with the changes described previously--and minor editorial 
changes. We have determined that these minor changes:
     Are consistent with the intent that was proposed in the 
NPRM (76 FR 72853, November 28, 2011) for correcting the unsafe 
condition; and
     Do not add any additional burden upon the public than was 
already proposed in the NPRM (76 FR 72853, November 28, 2011).

Interim Action

    We consider this AD interim action. If final action is identified 
later, we might consider further rulemaking then.

Costs of Compliance

    We estimate that this AD affects 596 airplanes of U.S. registry.
    We estimate the following costs to comply with this AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                Cost on U.S.
              Action                    Labor cost        Parts cost    Cost per product          operators
----------------------------------------------------------------------------------------------------------------
Inspections (required actions in   5 work-hours x $85            N/A  $425 per inspection   $253,300 per
 AD 2008-19-03, Amendment 39-       per hour = $425 per                cycle.                inspection cycle.
 15670 (73 FR 56958, October 1,     inspection cycle.
 2008).
New inspections..................  Between 7 and 15              N/A  Between $595 and      Between $354,620 and
                                    work-hours,                        $1,275 per            $759,900 per
                                    depending on                       inspection cycle.     inspection cycle.
                                    airplane
                                    configuration =
                                    between $595 and
                                    $1,275 per
                                    inspection cycle.
----------------------------------------------------------------------------------------------------------------

    We have received no definitive data that would enable us to provide 
a cost estimate for the on-condition actions or the optional 
terminating action specified in this AD.

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),
    (3) Will not affect intrastate aviation in Alaska, and
    (4) 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.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

[[Page 36136]]

Adoption of the Amendment

    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 removing airworthiness directive (AD) 
2008-19-03, Amendment 39-15670 (73 FR 56958, October 1, 2008), and 
adding the following new AD:

2012-12-04 The Boeing Company: Amendment 39-17083; Docket No. FAA-
2011-1254; Directorate Identifier 2010-NM-178-AD.

(a) Effective Date

    This airworthiness directive (AD) is effective July 23, 2012.

(b) Affected ADs

    This AD supersedes AD 2008-19-03, Amendment 39-15670 (73 FR 
56958, October 1, 2008).

(c) Applicability

    This AD applies to The Boeing Company Model 737-300, -400, and -
500 series airplanes, certificated in any category; as identified in 
Boeing Service Bulletin 737-53A1293, Revision 2, dated August 10, 
2011.

(d) Subject

    Joint Aircraft System Component (JASC)/Air Transport Association 
(ATA) of America Code 53, Fuselage.

(e) Unsafe Condition

    This AD was prompted by reports of additional crack findings of 
the fuselage skin at the chem-mill steps. We are issuing this AD to 
detect and correct fatigue cracking of the fuselage skin panels at 
the chem-mill steps, which could result in sudden fracture and 
failure of the fuselage skin panels, and consequent rapid 
decompression of the airplane.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Repetitive Inspections

    At the applicable times specified in paragraph 1.E., 
``Compliance,'' of Boeing Service Bulletin 737-53A1293, Revision 2, 
dated August 10, 2011, except as provided by paragraphs (j)(1) and 
(j)(2) of this AD: Do both a detailed inspection and a 
nondestructive inspection (NDI) (medium frequency eddy current, 
magneto optical imaging, C-scan, or ultrasonic phased array) to 
detect cracks in the fuselage skin along the chem-mill steps at 
stringers S-1 and S-2R, between station (STA) 400 and STA 460, in 
accordance with the Accomplishment Instructions of Boeing Service 
Bulletin 737-53A1293, Revision 2, dated August 10, 2011. Repeat the 
applicable inspections thereafter at intervals not to exceed those 
specified in paragraph 1.E., ``Compliance,'' of Boeing Service 
Bulletin 737-53A1293, Revision 2, dated August 10, 2011.

(h) Repair

    (1) If any crack is found during any inspection required by 
paragraph (g) of this AD, before further flight, repair in 
accordance with the Accomplishment Instructions of Boeing Service 
Bulletin 737-53A1293, Revision 2, dated August 10, 2011; except as 
provided by paragraph (h)(2) of this AD. Installation of a repair 
that meets the conditions specified in paragraph 1.E., 
``Compliance,'' of Boeing Service Bulletin 737-53A1293, Revision 2, 
dated August 10, 2011, terminates the repetitive inspections 
required by paragraph (g) of this AD for the repaired area only.
    (2) If any crack is found during any inspection required by 
paragraph (g) of this AD and Boeing Service Bulletin 737-53A1293, 
Revision 2, dated August 10, 2011, specifies to contact Boeing for 
repair: Before further flight, repair using a method approved in 
accordance with the procedures specified in paragraph (l) of this 
AD.

(i) Optional Modification

    Accomplishing a modification of the chem-milled steps at any 
location identified in Boeing Service Bulletin 737-53A1293, Revision 
2, dated August 10, 2011, using a method approved in accordance with 
the procedures specified in paragraph (l)(1) of this AD, terminates 
the repetitive inspections required by paragraph (g) of this AD for 
the modified area only.

(j) Exceptions to Service Bulletin

    (1) Where Boeing Service Bulletin 737-53A1293, Revision 2, dated 
August 10, 2011, specifies a compliance time relative to the date of 
Boeing Alert Service Bulletin 737-53A1293, Revision 1, dated July 7, 
2010, this AD requires compliance within the specified compliance 
time after the effective date of this AD.
    (2) Where the Condition column of paragraph 1.E., 
``Compliance,'' of Boeing Service Bulletin 737-53A1293, Revision 2, 
dated August 10, 2011, specifies a condition based on whether an 
airplane has or has not been inspected, this AD bases the condition 
on whether an airplane has or has not been inspected as of the 
effective date of this AD.
    (3) The post-repair inspection specified in Tables 4 and 6 of 
paragraph 1.E., ``Compliance,'' of Boeing Service Bulletin 737-
53A1293, Revision 2, August 10, 2011, is not required by this AD.

    Note 1 to paragraph (j)(3) of this AD: The damage tolerance 
inspections specified in Tables 4 and 6 of paragraph 1.E., 
``Compliance,'' of Boeing Service Bulletin 737-53A1293, Revision 2, 
August 10, 2011, may be used in support of compliance with section 
121.1109(c)(2) or 129.109(c)(2) of the Federal Aviation Regulations 
(14 CFR 121.1109(c)(2) or 14 CFR 129.109(c)(2)).

(k) Credit for Previous Actions

    This paragraph provides credit for the actions required by 
paragraphs (g), (h), and (i) of this AD, if those actions were 
performed before the effective date of this AD using Boeing Alert 
Service Bulletin 737-53A1293, Revision 1, dated July 7, 2010.

(l) Alternative Methods of Compliance (AMOCs)

    (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. In accordance with 14 CFR 39.19, send your request to your 
principal inspector or local Flight Standards District Office, as 
appropriate. If sending information directly to the manager of the 
ACO, send it to the attention of the person identified in the 
Related Information section of this AD. Information may be emailed 
to: 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov.
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the local flight standards district office/certificate holding 
district office.
    (3) An AMOC that provides an acceptable level of safety may be 
used for any repair required by this AD if it is approved by the 
Boeing Commercial Airplanes ODA that has been authorized by the 
Manager, Seattle ACO, to make those findings. For a repair method to 
be approved, the repair must meet the certification basis of the 
airplane, and the approval must specifically refer to this AD.
    (4) AMOCs approved for AD 2008-19-03, Amendment 39-15670 (73 FR 
56958, October 1, 2008), are approved as AMOCs for the corresponding 
requirements in this AD.

(m) Related Information

    For more information about this AD, contact Wayne Lockett, 
Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue SW., Renton, Washington 
98057-3356; phone: 425-917-6447; fax: 425-917-6590; email: 
wayne.lockett@faa.gov.

(n) Material Incorporated by Reference

    (1) You must use the following service information to do the 
actions required by this AD, unless the AD specifies otherwise. The 
Director of the Federal Register approved the incorporation by 
reference (IBR) of the following service information under 5 U.S.C. 
552(a) and 1 CFR part 51:
    (i) Boeing Service Bulletin 737-53A1293, Revision 2, dated 
August 10, 2011.
    (2) For service information identified in this AD, contact 
Boeing Commercial Airplanes, Attention: Data & Services Management, 
P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 
206-544-5000, extension 1; fax 206-766-5680; Internet https://www.myboeingfleet.com.
    (3) You may review copies of the referenced service information 
at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., 
Renton, Washington. For information on the availability of this 
material at the FAA, call 425-227-1221.
    (4) You may also review copies of the service information that 
is incorporated by

[[Page 36137]]

reference at the National Archives and Records Administration 
(NARA). For information on the availability of this material at 
NARA, call 202-741-6030, or go to: http://www.archives.gov/federal-register/cfr/ibr_locations.html.

    Issued in Renton, Washington, on May 31, 2012.
Michael Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2012-14377 Filed 6-15-12; 8:45 am]
BILLING CODE 4910-13-P
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