
[Federal Register Volume 76, Number 231 (Thursday, December 1, 2011)]
[Rules and Regulations]
[Pages 74667-74670]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-30608]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2011-0914; Directorate Identifier 2010-NM-166-AD; 
Amendment 39-16876; AD 2011-24-12]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Model 737-200, -
200C, -300, -400, and -500 Series 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 Model 737-300, -400, and -500 series airplanes. That AD 
currently requires repetitive external non-destructive inspections to 
detect cracks in the fuselage skin along the chem-mill step at 
stringers S-1 and S-2 right, between station (STA) 827 and STA 847, and 
repair if necessary. This new AD adds inspections for cracking in 
additional fuselage crown skin locations, and repair if necessary. This 
new AD also reduces the inspection thresholds for certain airplanes, 
extends certain repetitive inspection intervals, and adds airplanes to 
the applicability of the existing AD. This AD was prompted by reports 
of additional crack findings of the fuselage crown skin at the chem-
milled steps. We are issuing this AD to detect and correct fatigue 
cracking of the fuselage skin panels at the chem-milled 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 January 5, 2012.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in the AD as of January 5, 
2012.
    The Director of the Federal Register approved the incorporation by 
reference of a certain other publication listed in this AD as of 
February 16, 2010 (75 FR 1527, January 12, 2010).

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; Email 
me.boecom@boeing.com; 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 2010-01-09, Amendment 39-16167 (75 FR 1527, 
January 12, 2010). That AD applies to the specified products. The NPRM 
published in the Federal Register on September 1, 2011 (76 FR 54399). 
That NPRM proposed to continue to require repetitive external non-
destructive inspections to detect cracks in the fuselage skin along the 
chem-mill step at stringers S-1 and S-2 right, between station (STA) 
827 and STA 847, and repair if necessary. That NPRM also proposed to 
add inspections for cracking in additional fuselage crown skin 
locations, and repair if necessary. That NPRM also proposed to reduce 
the inspection thresholds for certain airplanes, extend certain 
repetitive inspection intervals, and add airplanes to the applicability 
of the existing AD.

Comments

    We gave the public the opportunity to participate in developing 
this AD. We have considered the comments received. Boeing and the 
National Transportation Safety Board support the NPRM.

Conclusion

    We reviewed the relevant data, considered the comments received, 
and determined that air safety and the public interest require adopting 
the AD as proposed.

Interim Action

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

Costs of Compliance

    We estimate that this AD affects 654 airplanes of U.S. registry.
    We estimate the following costs to comply with this AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                 Number of U.S.-
            Action                Work hours     Average labor      Cost per       registered       Fleet cost
                                                 rate per hour      product         airplanes
----------------------------------------------------------------------------------------------------------------
Inspection in AD 2010-01-09    2..............             $85  $170 per                    135  $22,950 per
 (75 FR 1527, January 12,                                        inspection                       inspection
 2010).                                                          cycle.                           cycle.

[[Page 74668]]

 
New inspection in this AD....  Between 2 and                85  Between $170                654  Between
                                30.                              and $2,550 per                   $111,180 and
                                                                 inspection                       $1,667,700 per
                                                                 cycle.                           inspection
                                                                                                  cycle.
----------------------------------------------------------------------------------------------------------------

    We have received no definitive data that would enable us to provide 
a cost estimate for the on-condition actions 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.

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) 
2010-01-09, Amendment 39-16167 (75 FR 1527, January 12, 2010), and 
adding the following new AD:

2011-24-12 The Boeing Company: Amendment 39-16876; Docket No. FAA-
2011-0914; Directorate Identifier 2010-NM-166-AD.

(a) Effective Date

    This airworthiness directive (AD) is effective January 5, 2012.

(b) Affected ADs

    This AD supersedes AD 2010-01-09, Amendment 39-16167 (75 FR 
1527, January 12, 2010).

(c) Applicability

    This AD applies to all The Boeing Company Model 737-200, -200C, 
-300, -400, and -500 series airplanes, certificated in any category.

(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 crown skin at the chem-milled steps. We are issuing 
this AD to detect and correct fatigue cracking of the fuselage skin 
panels at the chem-milled 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.

Restatement of Requirements of AD 2010-01-09, Amendment 39-16167 (75 FR 
1527, January 12, 2010)

(g) Initial and Repetitive Inspections

    For airplanes identified in Boeing Alert Service Bulletin 737-
53A1301, dated September 3, 2009: Before the accumulation of 35,000 
total flight cycles, or within 500 flight cycles after February 16, 
2010 (the effective date of AD 2010-01-09), whichever occurs later, 
except as provided by paragraph (i) of this AD, do an external non-
destructive inspection (NDI) to detect cracks in the fuselage skin 
along the chem-mill steps at stringers S-1 and S-2 right, between 
station (STA) 827 and STA 847, in accordance with the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1301, dated 
September 3, 2009; or Boeing Alert Service Bulletin 737-53A1301, 
Revision 2, dated April 25, 2011. If no cracking is found, repeat 
the inspection thereafter at intervals not to exceed 500 flight 
cycles; except as provided by paragraphs (i) and (n) of this AD. 
Accomplishing the inspections required by paragraph (j) of this AD 
terminates the inspections required by this paragraph.

(h) Repair

    If any crack is found during any inspection required by 
paragraph (g) of this AD, and Boeing Alert Service Bulletin 737-
53A1301, dated September 3, 2009; or Boeing Alert Service Bulletin 
737-53A1301, Revision 2, dated April 25, 2011; specifies to contact 
Boeing for repair instructions: Before further flight, repair the 
crack using a method approved in accordance with the procedures 
specified in paragraph (q) of this AD.

(i) Optional Terminating Action for Repetitive Inspections in Paragraph 
(g) of This AD

    Installing an external repair doubler along the chem-milled 
steps at stringers S-1 and S-2 right, between STA 827 and STA 847, 
constitutes terminating action for the repetitive inspections 
required by paragraph (g) of this AD for the repaired area only, 
provided all of the conditions specified in paragraphs (i)(1), 
(i)(2), and (i)(3) of this AD are met.
    (1) The repair is installed after September 3, 2009;
    (2) The repair was approved by the FAA or by a Boeing Company 
Authorized Representative or the Boeing Commercial Airplanes 
Organization Designation

[[Page 74669]]

Authorization (ODA) that has been authorized by the Manager, Seattle 
Aircraft Certification Office (ACO), FAA, to make such findings; and
    (3) The repair extends a minimum of three rows of fasteners on 
each side of the chem-mill line in the circumferential direction.

New Inspections Including Additional Locations and Reduced Inspection 
Intervals

(j) Groups 1 Through 25: Initial and Repetitive Inspections

    For Groups 1 through 25 airplanes identified in Boeing Alert 
Service Bulletin 737-53A1301, Revision 2, dated April 25, 2011: 
Except as provided by paragraph (k) of this AD, at the applicable 
time specified in paragraph 1.E., ``Compliance,'' of Boeing Alert 
Service Bulletin 737-53A1301, Revision 2, dated April 25, 2011, do 
the applicable inspections required by paragraphs (j)(1) and (j)(2) 
of this AD, in accordance with paragraphs 3.B.1 through 3.B.25 of 
the Accomplishment Instructions of Boeing Alert Service Bulletin 
737-53A1301, Revision 2, dated April 25, 2011. If no cracking is 
found, repeat the applicable inspections thereafter at the 
applicable intervals specified in paragraph 1.E., ``Compliance,'' of 
Boeing Alert Service Bulletin 737-53A1301, Revision 2, dated April 
25, 2011; except as provided by paragraphs (m) and (n) of this AD. 
Doing the inspections required by this paragraph terminates the 
inspections required by paragraph (g) of this AD.
    (1) For Groups 2, 8, 10, 13 through 18, and 21 through 25 
airplanes: Do a detailed inspection and an external non-destructive 
inspection (NDI) (medium frequency eddy current inspection, magneto 
optical imaging inspection, c-scan inspection, or ultrasonic phased 
array inspection) for cracking in the fuselage skin at the chem-mill 
steps at stringers S-1 and S-2R between STA 827 and STA 847, as 
identified in the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-53A1301, Revision 2, dated April 25, 2011.
    (2) For Groups 1 through 25 airplanes: Do a detailed inspection 
and an external NDI (medium frequency eddy current inspection; 
magneto optical imaging inspection, c-scan inspection, or ultrasonic 
phased array inspection) for cracking in the fuselage skin at the 
chem-mill steps at the specified locations other than at S-1 and S-
2R between STA 827 and STA 847, as identified in the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1301, Revision 
2, dated April 25, 2011.

    Note 1:  Option 1 of Boeing Alert Service Bulletin 737-53A1301, 
Revision 2, dated April 25, 2011, specifies a detailed inspection, 
and one additional inspection (external NDI, medium frequency eddy 
current inspection, magneto optical imaging inspection, or c-scan 
inspection). Option 2 of Boeing Alert Service Bulletin 737-53A1301, 
Revision 2, dated April 25, 2011, specifies a detailed inspection 
and an external ultrasonic phased array inspection. These options 
have different compliance times after the initial inspection.

(k) Exception

    Where Boeing Alert Service Bulletin 737-53A1301, Revision 2, 
dated April 25, 2011, specifies a compliance time after ``the date 
of Revision 1,'' or ``the date of Revision 2'' of that service 
bulletin, this AD requires compliance within the specified time 
after the effective date of this AD.

(l) Repair

    If any crack is found during any inspection required by 
paragraph (j) of this AD: Before further flight, repair the crack 
using a method approved in accordance with the procedures specified 
in paragraph (q) of this AD. Doing the repair ends the repetitive 
inspections required by paragraph (j) for the repaired area only.

(m) Optional Terminating Action for Repetitive Inspections

    Installing an external repair doubler along the chem-milled 
steps at any location identified in Boeing Alert Service Bulletin 
737-53A1301, Revision 2, dated April 25, 2011, constitutes 
terminating action for the repetitive inspections required by 
paragraph (j) of this AD for the repaired area only, provided all of 
the conditions specified in paragraphs (m)(1), (m)(2), and (m)(3) of 
this AD are met.
    (1) The repair is installed after the applicable date specified 
in paragraph (m)(1)(i) and (m)(1)(ii) of this AD.
    (i) For repairs at S-1 and S-2R between STA 827 and STA 847: 
Installed after September 3, 2009.
    (ii) For repairs at locations other than at S-1 and S-2R between 
STA 827 and STA 847: Installed after June 7, 2010.
    (2) The repair was approved by the FAA or by a Boeing Company 
Authorized Representative or the Boeing Commercial Airplanes 
Organization Designation Authorization (ODA) that has been 
authorized by the Manager, Seattle Aircraft Certification Office 
(ACO) to make such findings; and
    (3) The repair extends a minimum of three rows of fasteners on 
each side of the chem-mill line in the circumferential direction.

(n) Modification

    Accomplishing a modification of the chem-milled steps at any 
location identified in Boeing Alert Service Bulletin 737-53A1301, 
Revision 2, dated April 25, 2011, using a method approved in 
accordance with the procedures specified in paragraph (q)(1) of this 
AD, terminates the repetitive inspections required by paragraphs (g) 
and (j) of this AD for the modified area only.

(o) Group 26 Airplanes

    For Group 26 airplanes identified in Boeing Alert Service 
Bulletin 737-53A1301, Revision 2, dated April 25, 2011: Within 1,800 
flight cycles after the effective date of this AD, accomplish 
applicable inspections and corrective action, as identified in the 
service bulletin, using a method approved in accordance with the 
procedures specified in paragraph (q)(1) of this AD.

(p) Credit for Actions Accomplished in Accordance With Previous Service 
Information

    Actions done before the effective date of this AD in accordance 
with Boeing Alert Service Bulletin 737-53A1301, Revision 1, dated 
June 7, 2010, are acceptable for compliance with the corresponding 
requirements of this AD.

(q) 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.

(r) 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.

(s) Material Incorporated by Reference

    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) under 5 U.S.C. 552(a) and 1 CFR part 51 of the following 
service information on the date specified:
    (1) Boeing Alert Service Bulletin 737-53A1301, Revision 2, dated 
April 25, 2011, approved for IBR January 5, 2012.
    (2) Boeing Alert Service Bulletin 737-53A1301, dated September 
3, 2009, approved for IBR February 16, 2010 (75 FR 1527, January 12, 
2010).
    (3) 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; email 
me.boecom@boeing.com; Internet https://www.myboeingfleet.com.
    (4) You may review copies of the 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.

[[Page 74670]]

    (5) You may also review copies of the service information that 
is incorporated by reference at the National Archives and Records 
Administration (NARA). For information on the availability of this 
material at an NARA facility, 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 November 17, 2011.
John P. Piccola,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2011-30608 Filed 11-30-11; 8:45 am]
BILLING CODE 4910-13-P


