```

[Federal Register Volume 80, Number 229 (Monday, November 30, 2015)]
[Proposed Rules]
[Pages 74731-74734]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-30217]

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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2015-6538; Directorate Identifier 2015-NM-031-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 adopt a new airworthiness directive (AD) for 
certain The Boeing Company Model 737-100, -200, -200C, -300, -400, and 
-500 series airplanes. This proposed AD was prompted by an evaluation 
by the design approval holder (DAH) indicating that the bulkhead is 
subject to widespread fatigue damage (WFD). This proposed AD would 
require repetitive inspections of the aft pressure bulkhead web for any 
cracking, incorrectly drilled fastener holes, and elongated fastener 
holes, and related investigative and corrective actions if necessary. 
We are proposing this AD to detect and correct fatigue cracking of the 
aft pressure bulkhead web at the ``Y''-chord, which could result in 
reduced structural integrity of the airplane and rapid decompression of 
the fuselage.

DATES: We must receive comments on this proposed AD by January 14, 
2016.

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, WA 98124-2207; telephone 206-544-5000, 
extension 1; fax 206-766-5680; Internet https://www.myboeingfleet.com. 
You may view this referenced service information at the FAA, Transport 
Airplane Directorate, 1601 Lind Avenue SW., Renton, WA. For information 
on the availability of this material at the FAA, call 425-227-1221. It 
is also available on the Internet at http://www.regulations.gov by 
searching for and locating Docket No. FAA-2015-6538.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2015-
6538; or in person at the Docket Management Facility between 9 a.m.

[[Page 74732]]

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: Alan Pohl, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office 
(ACO), 1601 Lind Avenue SW., Renton, WA 98057-3356; telephone: 425-917-
6450; fax: 425-917-6590; email: Alan.Pohl@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-2015-6538; 
Directorate Identifier 2015-NM-031-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

    Structural fatigue damage is progressive. It begins as minute 
cracks, and those cracks grow under the action of repeated stresses. 
This can happen because of normal operational conditions and design 
attributes, or because of isolated situations or incidents such as 
material defects, poor fabrication quality, or corrosion pits, dings, 
or scratches. Fatigue damage can occur locally, in small areas or 
structural design details, or globally. Global fatigue damage is 
general degradation of large areas of structure with similar structural 
details and stress levels. Multiple-site damage is global damage that 
occurs in a large structural element such as a single rivet line of a 
lap splice joining two large skin panels. Global damage can also occur 
in multiple elements such as adjacent frames or stringers. Multiple-
site-damage and multiple-element-damage cracks are typically too small 
initially to be reliably detected with normal inspection methods. 
Without intervention, these cracks will grow, and eventually compromise 
the structural integrity of the airplane, in a condition known as 
widespread fatigue damage (WFD). As an airplane ages, WFD will likely 
occur, and will certainly occur if the airplane is operated long enough 
without any intervention.
    The FAA's WFD final rule (75 FR 69746, November 15, 2010) became 
effective on January 14, 2011. The WFD rule requires certain actions to 
prevent structural failure due to WFD throughout the operational life 
of certain existing transport category airplanes and all of these 
airplanes that will be certificated in the future. For existing and 
future airplanes subject to the WFD rule, the rule requires that DAHs 
establish a limit of validity (LOV) of the engineering data that 
support the structural maintenance program. Operators affected by the 
WFD rule may not fly an airplane beyond its LOV, unless an extended LOV 
is approved.
    The WFD rule (75 FR 69746, November 15, 2010) does not require 
identifying and developing maintenance actions if the DAHs can show 
that such actions are not necessary to prevent WFD before the airplane 
reaches the LOV. Many LOVs, however, do depend on accomplishment of 
future maintenance actions. As stated in the WFD rule, any maintenance 
actions necessary to reach the LOV will be mandated by airworthiness 
directives through separate rulemaking actions.
    In the context of WFD, this action is necessary to enable DAHs to 
propose LOVs that allow operators the longest operational lives for 
their airplanes, and still ensure that WFD will not occur. This 
approach allows for an implementation strategy that provides 
flexibility to DAHs in determining the timing of service information 
development (with FAA approval), while providing operators with 
certainty regarding the LOV applicable to their airplanes.
    We have received an evaluation by the design approval holder (DAH) 
indicating that the aft pressure bulkhead is subject to WFD. Cracks 
have been reported in the aft pressure bulkhead web at the web-to-
``Y''-chord interface and have occurred in the aft row of fasteners 
connecting the aft pressure bulkhead web to the ``Y''-chord. This 
condition, if not corrected, could result in fatigue cracking of the 
aft pressure bulkhead web at the ``Y''-chord, which could result in 
reduced structural integrity of the airplane and rapid decompression of 
the fuselage.

Related Service Information Under 1 CFR Part 51

    We reviewed Boeing Alert Service Bulletin 737-53A1214, Revision 5, 
dated January 30, 2015. This service information describes, among other 
actions, procedures for repetitive inspections of the aft pressure 
bulkhead web for any cracking, incorrectly drilled fastener holes, and 
elongated fastener holes; and related investigative and corrective 
actions. This service information is reasonably available because the 
interested parties have access to it through their normal course of 
business or by the means identified in the ADDRESSES section of this 
AD.

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 accomplishing the actions specified 
in the service information described previously, except as discussed 
under ``Differences Between this Proposed AD and the Service 
Information.'' Refer to this service information for details on the 
procedures and compliance times.
    The phrase ``related investigative actions'' is used in this 
proposed AD. ``Related investigative actions'' are follow-on actions 
that (1) are related to the primary action, and (2) further investigate 
the nature of any condition found. Related investigative actions in an 
AD could include, for example, inspections.
    The phrase ``corrective actions'' is used in this proposed AD. 
``Corrective actions'' correct or address any condition found. 
Corrective actions in an AD could include, for example, repairs.

Differences Between This Proposed AD and the Service Information

    AD 2012-18-13 R1, Amendment 39-17429 (78 FR 27020, May 9, 2013), 
refers to Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated 
December 16, 2011, as an appropriate source of service information for 
doing certain actions required by that AD. Since AD 2012-18-13 R1 was 
issued, Boeing issued Alert Service Bulletin 737-53A1214, Revision 5, 
dated January 30, 2015, to address WFD by adding new inspections 
specified in tables 9, 10, and 11 of paragraph 1.E.,

[[Page 74733]]

``Compliance,'' of Boeing Alert Service Bulletin 737-53A1214, Revision 
5, dated January 30, 2015. Boeing determined that the WFD-based 
inspections specified in tables 9, 10, and 11 of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1214, Revision 
5, dated January 30, 2015, affect only Group 2 airplanes because Group 
1 airplanes will reach their limit of validity before the compliance 
times specified in tables 9, 10, and 11 (Group 1 is for airplanes 
having line numbers 1 through 2565; Group 2 is for airplanes having 
line numbers 2566 through 3132).
    Therefore, although Boeing Alert Service Bulletin 737-53A1214, 
Revision 5, dated January 30, 2015, is effective for all The Boeing 
Company Model 737-100, -200, -200C, -300, -400, and -500 series 
airplanes, this proposed AD applies to only certain The Boeing Company 
Model 737-100, -200, -200C, -300, -400, and -500 series airplanes 
(i.e., Group 2 airplanes). This difference is due to the fact that this 
proposed AD only addresses the new WFD inspections specified in Boeing 
Alert Service Bulletin 737-53A1214, Revision 5, dated January 30, 2015.
    Accomplishing the actions required by paragraphs (g) and (h) of 
this proposed AD would terminate the inspections required by paragraphs 
(k) and (l) of AD 2012-18-13 R1, Amendment 39-17429 (78 FR 27020, May 
9, 2013).
    The service bulletin 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.

Costs of Compliance

    We estimate that this proposed AD affects 122 airplanes of U.S. 
registry.
    We estimate the following costs to comply with this proposed AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                             Parts                              Cost on U.S.
              Action                      Labor cost          cost      Cost per product          operators
----------------------------------------------------------------------------------------------------------------
Inspections of the web at the       Up to 60 work-hours x         $0  Up to $5,100 per      Up to $622,200
 ``Y''[dash]chord.                   $85 per hour = Up to              inspection cycle.    per inspection
                                     $5,100 per                                              cycle.
                                     inspection cycle.
----------------------------------------------------------------------------------------------------------------

    We have received no definitive data that would enable us to provide 
cost estimates 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 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),
    (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

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 airworthiness 
directive (AD):

The Boeing Company: Docket No. FAA-2015-6538; Directorate Identifier 
2015-NM-031-AD.

(a) Comments Due Date

    We must receive comments by January 14, 2016.

(b) Affected ADs

    This AD affects AD 2012-18-13 R1, Amendment 39-17429 (78 FR 
27020, May 9, 2013).

(c) Applicability

    This AD applies to The Boeing Company Model 737-100, -200, -
200C, -300, -400, and -500 series airplanes, certificated in any 
category, identified as Group 2 in Boeing Alert Service Bulletin 
737-53A1214, Revision 5, dated January 30, 2015.

(d) Subject

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

(e) Unsafe Condition

    This AD was prompted by an evaluation by the design approval 
holder indicating that the aft pressure bulkhead is subject to 
widespread fatigue damage. We are issuing this AD to detect and 
correct fatigue cracking of the aft pressure bulkhead web at the 
``Y''-chord, which could result in reduced structural integrity of 
the airplane and rapid decompression of the fuselage.

(f) Compliance

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

[[Page 74734]]

(g) Repetitive Inspections of the Aft Pressure Bulkhead Web at the 
``Y''-Chord Upper Bulkhead

    At the applicable time specified in tables 9 and 10 of paragraph 
1.E., ``Compliance,'' of Boeing Alert Service Bulletin 737-53A1214, 
Revision 5, dated January 30, 2015: Do detailed and low frequency 
eddy current (LFEC) inspections from the aft side of the aft 
pressure bulkhead web, or do detailed and high frequency eddy 
current (HFEC) inspections from the forward side of the aft pressure 
bulkhead web, for any cracking, incorrectly drilled fastener hole, 
and elongated fastener hole, and do all applicable related 
investigative and corrective actions, in accordance with Part I of 
the Accomplishment Instructions of Boeing Alert Service Bulletin 
737-53A1214, Revision 5, dated January 30, 2015, except as required 
by paragraph (i) of this AD. Do all related investigative and 
corrective actions before further flight. If any cracking, 
incorrectly drilled fastener hole, or elongated fastener hole is 
found, before further flight, repair the web using a method approved 
in accordance with the procedures specified in paragraph (l) of this 
AD. Thereafter, repeat the inspections at the applicable times 
specified in tables 9 and 10 of paragraph 1.E., ``Compliance'' of 
Boeing Alert Service Bulletin 737-53A1214, Revision 5, dated January 
30, 2015.

(h) Repetitive Inspections of the Aft Pressure Bulkhead Web at the 
``Y''-Chord Below S-15

    At the applicable time specified in table 11 of 1.E., 
``Compliance'' of Boeing Alert Service Bulletin 737-53A1214, 
Revision 5, dated January 30, 2015: Do detailed and eddy current 
inspections of the web from the forward or aft side of the bulkhead 
for any cracking, incorrectly drilled fastener hole, and elongated 
fastener hole, and do all applicable corrective actions, in 
accordance with Part III of the Accomplishment Instructions of 
Boeing Alert Service Bulletin 737-53A1214, Revision 5, dated January 
30, 2015, except as required by paragraph (i) of this AD. Do all 
corrective actions before further flight. If any cracking, 
incorrectly drilled fastener hole, or elongated fastener hole is 
found, before further flight, repair the web using a method approved 
in accordance with the procedures specified in paragraph (l) of this 
AD. Thereafter, repeat the inspections at the applicable times 
specified in table 11 of paragraph 1.E., ``Compliance,'' of Boeing 
Alert Service Bulletin 737-53A1214, Revision 5, dated January 30, 
2015.

(i) Exception to the Service Information

    Where Boeing Alert Service Bulletin 737-53A1214, Revision 5, 
dated January 30, 2015, specifies to contact Boeing for repair 
instructions: Before further flight, repair using a method approved 
in accordance with the procedures specified in paragraph (l) of this 
AD.

(j) Terminating Action for Other Rulemaking

    Accomplishing the actions required by paragraphs (g) and (h) of 
this AD terminates the inspections required by paragraphs (k) and 
(l) of AD 2012-18-13 R1, Amendment 39-17429 (78 FR 27020, May 9, 
2013).

(k) Credit for Previous Actions

    This paragraph provides credit for the actions required by 
paragraphs (g) and (h) of this AD, if the actions were performed 
before the effective date of this AD using Boeing Alert Service 
Bulletin 737-53A1214, Revision 4, dated December 16, 2011, which is 
not incorporated by reference in this AD.

(l) 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 paragraph (m)(1) 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 airplane, and the approval must 
specifically refer to this AD.

(m) Related Information

    (1) For more information about this AD, contact Alan Pohl, 
Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft 
Certification Office (ACO), 1601 Lind Avenue SW., Renton, WA 98057-
3356; telephone: 425-917-6450; fax: 425-917-6590; email: 
Alan.Pohl@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, WA 98124-2207; telephone 206-544-
5000, extension 1; fax 206-766-5680; Internet https://www.myboeingfleet.com. You may view this referenced service 
information at the FAA, Transport Airplane Directorate, 1601 Lind 
Avenue SW., Renton, WA. For information on the availability of this 
material at the FAA, call 425-227-1221.

     Issued in Renton, Washington, on November 20, 2015.
Jeffrey E. Duven,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2015-30217 Filed 11-27-15; 8:45 am]
 BILLING CODE 4910-13-P
```