```

[Federal Register Volume 75, Number 248 (Tuesday, December 28, 2010)]
[Rules and Regulations]
[Pages 81409-81412]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-32354]

=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2010-0437; Directorate Identifier 2009-NM-130-AD; 
Amendment 39-16539; AD 2010-25-06]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Model 737-200, -300, 
-400, and -500 Series Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: We are adopting a new airworthiness directive (AD) for certain 
Model 737-200, -300, -400, and -500 series airplanes. This AD requires 
repetitive inspections for cracking of certain fuselage frames and stub 
beams, and corrective actions if necessary. This AD also provides for 
an optional repair, which would terminate the repetitive inspections. 
For airplanes on which a certain repair is done, this AD also requires 
repetitive inspections for cracking of certain fuselage frames and stub 
beams, and corrective actions if necessary. This AD results from 
reports of the detection of fatigue cracks at certain frame sections, 
in addition to stub beam cracking, caused by high flight cycle stresses 
from both pressurization and maneuver loads. We are issuing this AD to 
detect and correct fatigue cracking of certain fuselage frames and stub 
beams and possible

[[Page 81410]]

severed frames, which could result in reduced structural integrity of 
the frames. This reduced structural integrity can increase loading in 
the fuselage skin, which will accelerate skin crack growth and could 
result in rapid decompression of the fuselage.

DATES: This AD is effective February 1, 2011.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in the AD as of February 1, 
2011.

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; e-mail me.boecom@boeing.com; 
Internet https://www.myboeingfleet.com.

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 (telephone 800-647-5527) is the 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; telephone (425) 
917-6447; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Discussion

    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 
part 39 to include an airworthiness directive (AD) that would apply to 
certain Model 737-200, -300, -400, and -500 series airplanes. That NPRM 
was published in the Federal Register on May 7, 2010 (75 FR 25124). 
That NPRM proposed to require repetitive inspections for cracking of 
certain fuselage frames and stub beams, and corrective actions if 
necessary. That NPRM also proposed an optional repair, which would 
terminate the repetitive inspections. For airplanes on which a certain 
repair is done, that NPRM also proposed to require repetitive 
inspections for cracking of certain fuselage frames and stub beams, and 
corrective actions if necessary.

Comments

    We gave the public the opportunity to participate in developing 
this AD. We considered the comments received.

Request To Change Paragraph (i)

    Boeing asked that paragraph (i) of the NPRM be changed to include a 
high frequency eddy current (HFEC) inspection. Boeing stated that 
Boeing Alert Service Bulletin 737-53A1254, Revision 1, dated July 9, 
2009, provides two options for inspections: detailed and HFEC. Boeing 
added that for areas where the repair hinders the inspection, both 
detailed and HFEC inspection options were provided, depending on which 
option was chosen for the original inspection.
    We agree with the commenter for the reasons provided. We have 
changed paragraph (i) of this AD to include an option for the HFEC 
inspection.

Request To Change Compliance Time

    Boeing also asked that the compliance time specified in paragraph 
(g)(3) of the NPRM be changed to ``the sooner of (i) within 4,500 
flight cycles after the effective date of the AD or (ii) within 9,000 
flight cycles after the previous inspection done in accordance with 
Boeing Alert Service Bulletin 737-53A1254, dated February 17, 2005.'' 
Boeing stated that new data indicate that the repeat interval for the 
area below the floor should be changed to 9,000 flight cycles from 
4,500 flight cycles. Boeing added that for airplanes on which the 
inspection in the original issue of Boeing Alert Service Bulletin 737-
53A1254 has been done, the compliance time as written in Boeing Alert 
Service Bulletin 737-53A1254, Revision 1 (i.e., 3,000 flight cycles 
from release of Revision 1 or 4,500 flight cycles from previous 
inspection, whichever is sooner), could cause a significant impact by 
putting some airplanes out of compliance. Boeing noted that the NPRM 
could potentially allow a longer compliance time than that in the 
original issue of the service bulletin. Boeing recommends that 
paragraph (g)(3) be changed as specified previously.
    We acknowledge the commenter's concern and provide the following. 
The compliance times required by paragraph (g) are at the ``later of,'' 
not the ``sooner of,'' the compliance times specified in paragraphs 
(g)(3)(i) and (g)(3)(ii). We agree that the compliance times specified 
in paragraphs (g)(3)(i) and (g)(3)(ii) of this AD are somewhat 
confusing and can be clarified. Therefore, we have combined paragraphs 
(g)(3)(i) and (g)(3)(ii) with paragraph (g)(3) to provide that 
clarification.

Request To Change Initial Inspection Threshold

    Southwest Airlines asked that the initial inspection threshold 
required by paragraphs (g)(1) and (g)(2) of the NPRM be changed. 
Southwest stated that the specified threshold will pose a significant 
burden on its airline to complete the inspections within the required 
timeframe. Southwest projected that half of its Model 737-300 and -500 
fleet will require an out-of-sequence maintenance visit to support this 
inspection threshold. Southwest added that this is based on its current 
substantial maintenance schedule, fleet utilization, and the proposed 
compliance thresholds based on each airplane's total flight cycles.
    We do not agree with the commenter's request. No supporting data 
were submitted proposing alternative inspection thresholds to maintain 
an adequate level of safety for its fleet. However, under the 
provisions of paragraph (m) of this AD, we will consider requests for 
approval of an alternative inspection threshold if sufficient data are 
submitted to substantiate that changing the initial inspection 
threshold would provide an acceptable level of safety. We have not 
changed the AD in this regard.

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. We also determined that 
these changes will not increase the economic burden on any operator or 
increase the scope of the AD.

Costs of Compliance

    We estimate that this AD affects 635 airplanes of U.S. registry. 
The following table provides the estimated costs for U.S. operators to 
comply with this AD.

[[Page 81411]]

                                             Table--Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                Average                          Number of
                                       Work      labor                             U.S.-
              Action                  hours     rate per    Cost per product    registered       Fleet cost
                                                  hour                           airplanes
----------------------------------------------------------------------------------------------------------------
BS 616 and BS 639 inspection/lower         15        $85  $1,275 per                   635  $809,625 per
 frame and stub beam.                                      inspection cycle.                 inspection cycle.
----------------------------------------------------------------------------------------------------------------

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

    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 under the criteria 
of the Regulatory Flexibility Act.
    You can find our regulatory evaluation and the estimated costs of 
compliance in the AD Docket.

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 AD:

2010-25-06 The Boeing Company: Amendment 39-16539. Docket No. FAA-
2010-0437; Directorate Identifier 2009-NM-130-AD.

Effective Date

    (a) This airworthiness directive (AD) is effective February 1, 
2011.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to The Boeing Company Model 737-200, -300, -
400, and -500 series airplanes, certificated in any category; as 
identified in Boeing Alert Service Bulletin 737-53A1254, Revision 1, 
dated July 9, 2009.

Subject

    (d) Air Transport Association (ATA) of America Code 53: 
Fuselage.

Unsafe Condition

    (e) This AD results from the detection of fatigue cracks at 
certain frame sections, in addition to stub beam cracking, caused by 
high flight cycle stresses from both pressurization and maneuver 
loads. The Federal Aviation Administration is issuing this AD to 
detect and correct fatigue cracking of certain fuselage frames and 
stub beams and possible severed frames, which could result in 
reduced structural integrity of the frames. This reduced structural 
integrity can increase loading in the fuselage skin, which will 
accelerate skin crack growth and could result in rapid decompression 
of the fuselage.

Compliance

    (f) You are responsible for having the actions required by this 
AD performed within the compliance times specified, unless the 
actions have already been done.

Repetitive Inspections and Corrective Actions

    (g) At the applicable time specified in paragraph (g)(1), 
(g)(2), or (g)(3) of this AD: Do a detailed or high frequency eddy 
current (HFEC) inspection for cracking of body station (BS) 616 and 
BS 639 frame webs, inner chord, and outer chord, and the stub beams; 
and do all applicable related investigative and corrective actions; 
by accomplishing all the actions specified in Part 1 of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1254, Revision 1, dated July 9, 2009, except as specified in 
paragraphs (i) and (j) of this AD. Do all applicable related 
investigative and corrective actions before further flight. 
Thereafter, repeat the inspection at intervals not to exceed 4,500 
flight cycles since accomplishing the detailed inspection or at 
intervals not to exceed 9,000 flight cycles since accomplishing the 
HFEC inspection, as applicable.
    (1) For airplanes on which no inspection of the BS 616 and BS 
639 frames specified in Boeing Alert Service Bulletin 737-53A1254, 
dated February 17, 2005, has been done as of the effective date of 
this AD, and that have accumulated fewer than 55,000 total flight 
cycles as of the effective date of this AD: Inspect within 3,000 
flight cycles after the effective date of this AD, or before the 
accumulation of 56,500 total flight cycles, whichever occurs first.
    (2) For airplanes on which no inspection of the BS 616 and BS 
639 frames specified in Boeing Alert Service Bulletin 737-53A1254, 
dated February 17, 2005, has been done as of the effective date of 
this AD, and that have accumulated 55,000 or more total flight 
cycles as of the effective date of this AD: Inspect within 1,500 
flight cycles after the effective date of this AD.
    (3) For airplanes on which a detailed or HFEC inspection of the 
BS 616 and BS 639 frames, specified in Boeing Alert Service Bulletin 
737-53A1254, dated February 17, 2005, has been done as of the 
effective date of this AD: Inspect within 4,500 flight cycles after 
the previous inspection done in accordance with Boeing Alert Service 
Bulletin 737-53A1254, dated February 17, 2005, or within 3,000 
flight cycles after the effective date of this AD, whichever occurs 
later.

Post-Repair Repetitive Inspections and Corrective Actions

    (h) For airplanes on which the repair specified in Part 4 of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1254, Revision 1, dated July 9, 2009, has been done: At the 
applicable time specified in paragraphs (h)(1) and (h)(2) of this 
AD, do a detailed or HFEC inspection for

[[Page 81412]]

cracking of the replacement frame section (frame webs, inner chord, 
and outer chord); and do all applicable related investigative and 
corrective actions; by accomplishing all the actions specified in 
Part 1 of the Accomplishment Instructions of Boeing Alert Service 
Bulletin 737-53A1254, Revision 1, dated July 9, 2009, except as 
specified in paragraphs (i) and (j) of this AD. Do all applicable 
related investigative and corrective actions before further flight. 
Thereafter, repeat the inspection at intervals not to exceed 4,500 
flight cycles since accomplishing the detailed inspection or at 
intervals not to exceed 9,000 flight cycles since accomplishing the 
HFEC inspection, as applicable.
    (1) For airplanes on which a partial frame splice repair at BS 
616 or BS 639 has been done, and the inner chord and web have been 
cold-worked: Inspect within 44,000 flight cycles after the repair 
has been done.
    (2) For airplanes on which a partial frame splice repair at BS 
616 or BS 639 has been done, and the inner chord and web have not 
been cold-worked: Inspect within 29,000 flight cycles after that 
repair has been done.

Alternative Inspection of Repaired or Modified Area

    (i) For airplanes on which a repair or preventative modification 
exists on the inner chord below the floor which prevents the 
accomplishment of the detailed or HFEC inspection in that area as 
required by paragraph (g) of this AD: In lieu of inspecting that 
area, do a detailed or HFEC inspection of the inner chord along the 
length of the repair and around the fastener heads in accordance 
with Part 1 of the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-53A1254, Revision 1, dated July 9, 2009.

Exceptions to Service Information

    (j) Where Boeing Alert Service Bulletin 737-53A1254, Revision 1, 
dated July 9, 2009, specifies to contact Boeing for repair 
instructions and repair: Before further flight, repair the cracking 
using a method approved in accordance with the procedures specified 
in paragraph (m) of this AD.
    (k) Although Boeing Alert Service Bulletin 737-53A1254, Revision 
1, dated July 9, 2009, specifies to submit information to the 
manufacturer, this AD does not include that requirement.

Terminating Action

    (l) Doing the repair specified in Part 4 of Boeing Alert Service 
Bulletin 737-53A1254, Revision 1, dated July 9, 2009, terminates the 
repetitive inspection requirements of paragraph (g) of this AD for 
the repaired frame only.

Alternative Methods of Compliance (AMOCs)

    (m)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, has the authority to approve AMOCs for this AD, if requested 
using the procedures found in 14 CFR 39.19. Send information to 
ATTN: Wayne Lockett, Aerospace Engineer, Airframe Branch, ANM-120S, 
FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., 
Renton, Washington 98057-3356; telephone (425) 917-6447; fax (425) 
917-6590. Or, e-mail information to 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov.
    (2) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Before using any approved AMOC on any airplane to which the AMOC 
applies, notify your principal maintenance inspector (PMI) or 
principal avionics inspector (PAI), as appropriate, or lacking a 
principal inspector, your local Flight Standards District Office. 
The AMOC approval letter must specifically reference this AD.
    (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 an 
Authorized Representative for the Boeing Commercial Airplanes 
Organization Designation Authorization (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.

Material Incorporated by Reference

    (n) You must use Boeing Alert Service Bulletin 737-53A1254, 
Revision 1, dated July 9, 2009, to do the actions required by this 
AD, unless the AD specifies otherwise.
    (1) The Director of the Federal Register approved the 
incorporation by reference of this service information under 5 
U.S.C. 552(a) and 1 CFR part 51.
    (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; e-mail 
me.boecom@boeing.com; Internet https://www.myboeingfleet.com.
    (3) 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.
    (4) 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 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 December 16, 2010.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2010-32354 Filed 12-27-10; 8:45 am]
BILLING CODE 4910-13-P
```