Document ID: FAA-2011-1254-0001
Agency: faa
Document Type: Proposed Rule
Title: Airworthiness Directives: Boeing Co. Airplanes
Posted Date: 2011-11-28T05:00Z

[Federal Register Volume 76, Number 228 (Monday, November 28, 2011)]
[Proposed Rules]
[Pages 72853-72855]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-30559]

 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
 
 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
 ========================================================================
 

  Federal Register / Vol. 76, No. 228 / Monday, November 28, 2011 / 
Proposed Rules  

[[Page 72853]]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2011-1254; Directorate Identifier 2010-NM-178-AD]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: We propose to supersede an existing airworthiness directive 
(AD) that applies to certain Model 737-300, -400, and -500 series 
airplanes. The existing 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. Since 
we issued that AD, we have received reports of additional crack 
findings of the fuselage skin at the chem-mill steps. This proposed AD 
would add inspections for cracking in additional fuselage skin 
locations, and repair if necessary. This proposed AD would also reduce 
the inspection thresholds and repetitive intervals for certain 
airplanes. We are proposing 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: We must receive comments on this proposed AD by January 12, 
2012.

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: 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 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 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 proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2011-1254; 
Directorate Identifier 2010-NM-178-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

    On September 11, 2008, we issued AD 2008-19-03, Amendment 39-15670 
(73 FR 56958, October 1, 2008), for certain Model 737-300, -400, and -
500 series airplanes. That AD 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 STA 400 and STA 460, and repair if necessary. That AD resulted 
from reports of cracks in the fuselage skin common to stringers S-1 and 
S-2R, between STA 400 and STA 460. We issued that 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.

Actions Since Existing AD Was Issued

    Since we issued AD 2008-19-03, Amendment 39-15670 (73 FR 56958, 
October 1, 2008), we received reports of new findings of cracking in 
the fuselage skin at the chem-mill steps adjacent to the Air Traffic 
Control antenna. One reported crack was on the inboard side of S-2R at 
STA 451; the crack measured one inch long. That airplane had 
accumulated 52,207 total flight cycles. Another reported crack was on 
the left-hand side of stringer S-1 at STA 431. That airplane had 
accumulated 43,565 total flight cycles. Other cracks were located on 
the left-hand side of stringer S-1, between STA 400 and STA 460 on 
certain airplanes. The cause of the cracking was fatigue due to high-
tension stresses and local bending at the edge of the chem-mill pockets 
of the bonded skin. It was also determined that the detailed inspection 
alone (one method required by the existing AD) is not adequate to 
detect the cracking.

Relevant Service Information

    We reviewed Boeing Alert Service Bulletin 737-53A1293, Revision 1,

[[Page 72854]]

dated July 7, 2010; and Boeing Service Bulletin 737-53A1293, Revision 
2, dated August 10, 2011. (Boeing Alert Service Bulletin 737-53A1293, 
dated August 13, 2008, was referred to for accomplishing the actions in 
AD 2008-19-03, Amendment 39-15670 (73 FR 56958, October 1, 2008)).
    Boeing Alert Service Bulletin 737-53A1293, Revision 1, dated July 
7, 2010, adds an ultrasonic phased array inspection to the options for 
non-destructive inspections (NDI) specified in Boeing Alert Service 
Bulletin 737-53A1293, dated August 13, 2008, and combines the detailed 
inspection and the NDI in lieu of doing either Option 1 (a detailed 
inspection) or Option 2 (an NDI). Boeing Service Bulletin 737-53A1293, 
Revision 2, dated August 10, 2011, clarifies repair instructions for 
specific findings.
    The initial inspection compliance times range between the 
following, depending on configuration: (1) Before the accumulation 
33,000 total flight cycles, or within 500 flight cycles after the date 
on this service bulletin, whichever is later; and (2) before the 
accumulation of 35,000 total flight cycles, or within 1,800 flight 
cycles after the date on this service bulletin, whichever is later.
    The repetitive inspection intervals range between 500 and 2,400 
flight cycles, depending on the inspection option and configuration.

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 these same type 
designs.

Proposed AD Requirements

    This proposed AD would retain certain requirements of AD 2008-19-
03, Amendment 39-15670 (73 FR 56958, October 1, 2008). This proposed AD 
would also require accomplishing the actions specified in Boeing 
Service Bulletin 737-53A1293, Revision 2, dated August 10, 2011, except 
as discussed under ``Differences Between the AD and the Service 
Information.''

Differences Between the AD and the Service Information

    Boeing Service Bulletin 737-53A1293, Revision 2, dated August 10, 
2011, specifies contacting the manufacturer for instructions on how to 
repair a certain condition, but this AD requires repairing that 
condition 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 an Authorized Representative 
for the Boeing Commercial Airplanes Delegation Option Authorization 
Organization whom we have authorized to make those findings.
    The post-repair inspection specified in Tables 4 and 6 of paragraph 
1.E., ``Compliance,'' of Boeing Service Bulletin 737-53A1293, Revision 
2, dated August 10, 2011, is not required by this proposed AD.

Interim Action

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

Costs of Compliance

    We estimate that this proposed AD affects 596 airplanes of U.S. 
registry.
    We estimate the following costs to comply with this proposed 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 (proposed action)  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 specified in this proposed 
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 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 that the 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.

[[Page 72855]]

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

The Boeing Company: Docket No. FAA-2011-1254; Directorate Identifier 
2010-NM-178-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by January 
12, 2012.

Affected ADs

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

Applicability

    (c) This AD applies to 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.

Subject

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

Unsafe Condition

    (e) 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.

Compliance

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

Repetitive Inspections

    (g) 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 paragraph (j) and (k) 
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.

Repair

    (h) 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 (i) 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.
    (i) 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 (n) of this 
AD.

Exceptions to Service Bulletin

    (j) Where Boeing Service Bulletin 737-53A1293, Revision 2, dated 
August 10, 2011, specifies a compliance time relative to the date on 
that service bulletin, this AD requires compliance within the 
specified compliance time after the effective date of this AD.
    (k) 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.
    (l) 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: 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)).

Credit for Actions Accomplished in Accordance With Previous Service 
Information

    (m) Actions done before the effective date of this AD in 
accordance with Boeing Alert Service Bulletin 737-53A1293, Revision 
1, July 7, 2010, are acceptable for compliance with the 
corresponding actions required by this AD.

Alternative Methods of Compliance (AMOCs)

    (n)(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.
    (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.

Related Information

    (o) 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.
    (p) 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.

    Issued in Renton, Washington, on November 16, 2011.
John P. Piccola,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2011-30559 Filed 11-25-11; 8:45 am]
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