
[Federal Register Volume 77, Number 107 (Monday, June 4, 2012)]
[Proposed Rules]
[Pages 32918-32921]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-13439]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2012-0491; Directorate Identifier 2011-NM-265-AD]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company 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 The Boeing Company Model 737-100, -200, and -200C series 
airplanes. This proposed AD was prompted by a report of a severed upper 
butt strap, and cracks in the forward skin and bonded doubler, on one 
airplane. This proposed AD would require repetitive inspections for 
cracks and a chemical spot test in the area of station (STA) 908, and 
related investigative and corrective actions, if necessary. For certain 
airplanes, this proposed AD would require an inspection and 
modification. We are proposing this AD to prevent cracks at the 
adjacent mating skins (forward and aft), which could initiate just 
above stringers S-4R and S-4L; and could grow and result in a 
decompression event.

DATES: We must receive comments on this proposed AD by July 19, 2012.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, 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: Deliver to Mail address above between 9 
a.m. 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; 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 98057-3356. 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 (phone: 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; phone: (425) 917-
6447; fax: (425) 917-6590; email: wayne.lockett@faa.gov.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposal. Send your comments to an address listed 
under the ADDRESSES section. Include ``Docket No. FAA-2012-0491; 
Directorate Identifier 2011-NM-265-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 received a report of a severed upper butt strap, and cracks in 
the forward skin and bonded doubler, on

[[Page 32919]]

one airplane. Lab analysis of the upper butt strap identified 7075-T6 
alloy, instead of the required 2024-T3 clad material. The airplane had 
accumulated approximately 61,000 total flight cycles and 58,000 total 
flight hours. The skin crack was found just above a previously 
installed lap joint modification. Such cracks, if not detected and 
corrected, could result in cracks at the adjacent mating skins (forward 
and aft), which could initiate just above stringers S-4R and S-4L; and 
could grow and result in a decompression event.

Relevant Service Information

    We reviewed Boeing Special Attention Service Bulletin 737-53-1313, 
dated November 3, 2011. For information on the procedures and 
compliance times, see this service information at http://www.regulations.gov by searching for Docket No. FAA-2012-0491.

FAA's Determination

    We are proposing this AD because we evaluated all the relevant 
information and determined the unsafe condition described previously is 
likely to exist or develop in other products of the same type design.

Proposed AD Requirements

    This proposed AD would require repetitive inspections (detailed, 
external low frequency eddy current (LFEC), or internal LFEC) for 
cracks and a chemical spot test in the area of STA 908, and related 
investigative and corrective actions, if necessary. Related 
investigative actions include a detailed inspection for corrosion of 
the skin, skin doubler, and lower butt strap; an open-hole high 
frequency eddy current (HFEC) inspection for cracks of the skin, skin 
doubler, lower butt strap, and stringer splices; and an open-hole HFEC 
for cracks of the STA 908 upper butt strap. Corrective actions involve 
repairing, installing a new stringer splice; and installing a new STA 
908 upper butt strap.
    For airplanes having line numbers 1 through 291, this proposed AD 
would require actions (inspection and modification) done in accordance 
with a method approved by the Manager, Seattle Aircraft Certification 
Office (ACO).

Differences Between the Proposed AD and the Service Information

    The service information specifies to contact the manufacturer for 
instructions on how to repair certain conditions, but this proposed AD 
would require repairing those conditions in one of the following ways:
     In accordance with 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) whom we have 
authorized to make those findings.
    In addition, Boeing has not provided specific procedures for 
airplanes having line numbers 1 through 291, but indicates to contact 
Boeing for instructions ``before further flight.'' The FAA is aware 
that only one of these airplanes is currently in operation, and it is a 
test bed airplane that is not used for revenue flights. This proposed 
AD requires operators to inspect and modify, as required, in accordance 
with a method approved by the Manager, Seattle ACO, within 120 days.

Costs of Compliance

    We estimate that this proposed AD affects 61 airplanes of U.S. 
registry.
    We estimate the following costs to comply with this proposed AD:

                                                                     Estimated Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                Action                            Labor cost            Parts cost      Cost per product                Cost on U.S. operators
--------------------------------------------------------------------------------------------------------------------------------------------------------
Inspection and test...................  166 work-hours x $85 per hour           $0  $14,110 per inspection    $860,710 per inspection cycle.
                                         = $14,110 per inspection                    cycle.
                                         cycle.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    In addition, we have received no definitive data that would enable 
us to provide cost estimates for the actions that would be required for 
Group 1 airplanes.
    We estimate the following costs to do any necessary related 
investigative actions, repairs, and installations that would be 
required based on the results of the proposed inspection and test. We 
have no way of determining the number of aircraft that might need these 
actions:

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                      Cost per
                    Action                                   Labor cost                Parts cost      product
----------------------------------------------------------------------------------------------------------------
Related investigative actions, repair,         173 work-hours x $85 per hour =                 $0       $14,705
 installation.                                  $14,705.
----------------------------------------------------------------------------------------------------------------

    According to the manufacturer, some of the costs of this proposed 
AD may be covered under warranty, thereby reducing the cost impact on 
affected individuals. We do not control warranty coverage for affected 
individuals. As a result, we have included all costs in our cost 
estimate.

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

[[Page 32920]]

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),
    (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.

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 
airworthiness directive (AD):

The Boeing Company: Docket No. FAA-2012-0491; Directorate Identifier 
2011-NM-265-AD.

(a) Comments Due Date

    We must receive comments by July 19, 2012.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to The Boeing Company Model 737-100, -200, and 
200C series airplanes; certificated in any category; as identified 
in Boeing Special Attention Service Bulletin 737-53-1313, dated 
November 3, 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 a report of a severed upper butt strap, 
and cracks in the forward skin and bonded doubler, on one airplane. 
We are issuing this AD to prevent cracks at the adjacent mating 
skins (forward and aft), which could initiate just above stringers 
S-4R and S-4L; and could grow and result in a decompression event.

(f) Compliance

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

(g) Actions for Group 1 Airplanes

    For Group 1 airplanes, as identified in Boeing Special Attention 
Service Bulletin 737-53-1313, dated November 3, 2011: Within 120 
days after the effective date of this AD, inspect and modify, as 
required, using a method approved in accordance with the procedures 
specified in paragraph (k) of this AD.

(h) Actions for Groups 2 and 3 Airplanes

    For Groups 2 and 3 airplanes, as identified in Boeing Special 
Attention Service Bulletin 737-53-1313, dated November 3, 2011: 
Except as provided by paragraph (i)(1) of this AD, at the applicable 
times identified in paragraph 1.E., ``Compliance,'' of Boeing 
Special Attention Service Bulletin 737-53-1313, dated November 3, 
2011, do the actions specified in paragraphs (h)(1) and (h)(2) of 
this AD, in accordance with the Accomplishment Instructions of 
Boeing Special Attention Service Bulletin 737-53-1313, dated 
November 3, 2011, except as provided by paragraph (i)(2) of this AD.
    (1) Do one of the inspection options identified in paragraphs 
(h)(1)(i), (h)(1)(ii), and (h)(1)(iii) of this AD; and do all 
applicable related investigative and corrective actions. Do all 
applicable related investigative and corrective actions before 
further flight.
    (i) Inspection Option 1: Do a detailed inspection for cracks of 
the station (STA) 908 forward and aft skin. Thereafter, repeat the 
inspection at intervals not to exceed 500 flight cycles until the 
chemical spot test required by paragraph (h)(2) of this AD is done.
    (ii) Inspection Option 2: Do a one-time external low-frequency 
eddy current (LFEC) inspection for cracks of the STA 908 upper butt 
strap.
    (iii) Inspection Option 3: Do a one-time internal LFEC 
inspection for cracks of the STA 908 upper butt strap.
    (2) Do a chemical spot test of the STA 908 upper butt strap to 
determine the part material, and do all applicable related 
investigative and corrective actions. Do all applicable related 
investigative and corrective actions at the times specified in 
paragraph 1.E., ``Compliance,'' of Boeing Special Attention Service 
Bulletin 737-53-1313, dated November 3, 2011, except as provided by 
paragraph (i)(1) of this AD. Confirming the upper butt strap is made 
from 2000 series aluminum terminates the inspections required by 
paragraph (h)(1) of this AD.

(i) Exceptions to the Service Information

    (1) Where Boeing Special Attention Service Bulletin 737-53-1313, 
dated November 3, 2011, specifies a compliance time ``after the 
original issue date of the service bulletin,'' this AD requires 
compliance within the specified compliance time after the effective 
date of this AD.
    (2) Where Boeing Special Attention Service Bulletin 737-53-1313, 
dated November 3, 2011, specifies to contact Boeing for repair 
instructions: Before further flight, repair using a method approved 
in accordance with the procedures specified in paragraph (k) of this 
AD.

(j) Terminating Action

    Replacing the STA 908 upper butt strap and doing all applicable 
related investigative and corrective actions, in accordance with 
Part 4, Part 5, and Part 6, in accordance with the Accomplishment 
Instructions of Boeing Special Attention Service Bulletin 737-53-
1313, dated November 3, 2011, except as provided by paragraph (i)(2) 
of this AD, terminates the inspections and chemical spot test 
required by this AD.

(k) Alternative Methods of Compliance (AMOCs)

    (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. 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 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, and the approval must 
specifically refer to this AD.

(l) Related Information

    (1) 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.
    (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; email 
me.boecom@boeing.com; Internet https://www.myboeingfleet.com. You 
may also review the referenced service information in the docket at 
www.regulations.gov (refer to Docket No. FAA-2012-0491. 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.


[[Page 32921]]


    Issued in Renton, Washington, on May 18, 2012.
Michael Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2012-13439 Filed 6-1-12; 8:45 am]
BILLING CODE 4910-13-P


