
[Federal Register Volume 75, Number 88 (Friday, May 7, 2010)]
[Proposed Rules]
[Pages 25124-25127]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-10902]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2010-0437; Directorate Identifier 2009-NM-130-AD]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt a new airworthiness directive (AD) for 
certain Model 737-200, -300, -400, and -500 series airplanes. This 
proposed AD would require repetitive inspections for cracking of 
certain fuselage frames and stub beams, and corrective actions if 
necessary. This proposed AD also provides for an optional repair, which 
would terminate the repetitive inspections. For airplanes on which a 
certain repair is done, this proposed AD would also require repetitive 
inspections for cracking of certain fuselage frames and stub beams, and 
corrective actions if necessary. This proposed 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 proposing 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.

DATES: We must receive comments on this proposed AD by June 21, 2010.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590, between 9 a.m.

[[Page 25125]]

and 5 p.m., Monday through Friday, except Federal holidays.
    For service information identified in this proposed 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. 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 proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Office (telephone 800-647-5527) is in the 
ADDRESSES section. Comments will be available in the AD docket shortly 
after receipt.

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:

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2010-0437; 
Directorate Identifier 2009-NM-130-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will consider all comments received by the closing date and may amend 
this proposed AD because of those comments.
    We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We 
will also post a report summarizing each substantive verbal contact we 
receive about this proposed AD.

Discussion

    We have received reports of fatigue cracks at certain frame 
sections, in addition to stub beam cracking. The fatigue cracking is 
caused by high flight cycle stresses from both pressurization and 
maneuver loads. Reduced structural integrity of the frames can increase 
loading in the fuselage skin, which will accelerate skin crack growth 
and could result in rapid decompression of the fuselage.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 737-53A1254, 
Revision 1, dated July 9, 2009. The service bulletin describes 
procedures for, among other actions, repetitive detailed inspections 
for cracks in the body station (BS) 616 and BS 639 frame webs, inner 
chord, and outer chord, and the stub beam, and corrective actions if 
necessary. The corrective actions include repair of any cracking before 
further flight. The procedures also recommend contacting Boeing for 
repair instructions for certain cracking and repairing before further 
flight.
    As an option to the detailed inspection, the service bulletin 
describes procedures for a high frequency eddy current (HFEC) 
inspection for cracks in the same areas, and repair of any crack found. 
The service bulletin also describes procedures for doing a detailed 
inspection of the inner chord along the length of the repair and around 
the fastener heads if a repair or preventative modification exists on 
the inner chord below the floor that prevents the accomplishment of the 
detailed or HFEC inspection in that area.
    For airplanes on which a certain repair is done, the service 
bulletin describes procedures for repetitive detailed or HFEC 
inspections for cracking of the replacement frame section (frame webs, 
inner chord, and outer chord), and contacting Boeing for repair 
instructions if any crack is found, and repairing before further 
flight.

FAA's Determination and Requirements of This Proposed AD

    We are proposing this AD because we evaluated all relevant 
information and determined the unsafe condition described previously is 
likely to exist or develop in other products of the same type design. 
This proposed AD would require accomplishing the actions specified in 
the service information described previously, except as discussed under 
``Differences Between the Proposed AD and Boeing Alert Service Bulletin 
737-53A1254, Revision 1, dated July 9, 2009.''

Differences Between the Proposed AD and Boeing Alert Service Bulletin 
737-53A1254, Revision 1, Dated July 9, 2009

    Although the service bulletin specifies economic inspections and 
repairs of BS 597 and BS 601 frames, this proposed AD would not require 
those inspections and repairs.
    Although the service bulletin does not address accomplishing the 
inspections for airplanes on which fewer than 15,000 total flight 
cycles have been accumulated, this proposed AD would require the 
inspections on those airplanes.
    The service bulletin specifies to contact the manufacturer for 
instructions on repairing cracks, but this proposed AD would require 
repairing cracks in one of the following ways:
     Using a method that we approve; or
     Using data that meet the certification basis of the 
airplane, and that have been approved by the Boeing Commercial 
Airplanes Organization Designation Authorization (ODA) that we have 
authorized to make those findings.

Costs of Compliance

    We estimate that this proposed AD would affect 635 airplanes of 
U.S. registry. 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     Cost per product       registered                     Fleet cost
                                                     rate per hour                            airplanes
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BS 616 and BS 639 inspection/                  15              $85   $1,275, per                      635   $809,625 per inspection cycle.
 lower frame and stub beam.                                           inspection cycle.
--------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 25126]]

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 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 this 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.
    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.

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 AD:

The Boeing Company: Docket No. FAA-2010-0437; Directorate Identifier 
2009-NM-130-AD.

Comments Due Date

    (a) We must receive comments by June 21, 2010.

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 at the later of the times 
specified in paragraphs (g)(3)(i) and (g)(3)(ii) of this AD.
    (i) Within 3,000 flight cycles after the effective date of this 
AD.
    (ii) Within 4,500 flight cycles after the previous inspection 
done in accordance with Boeing Alert Service Bulletin 737-53A1254, 
dated February 17, 2005.

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 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 inspection of the

[[Page 25127]]

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.

    Issued in Renton, Washington, on April 28, 2010.
Jeffrey E. Duven,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2010-10902 Filed 5-6-10; 8:45 am]
BILLING CODE 4910-13-P


