
[Federal Register Volume 82, Number 154 (Friday, August 11, 2017)]
[Proposed Rules]
[Pages 37546-37549]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-16358]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-0766; Product Identifier 2017-NM-046-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 all 
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 gore web lap splices 
of the aft pressure bulkhead are subject to widespread fatigue damage 
(WFD). This proposed AD would require repetitive inspections of the 
gore webs, gore web lap splices, and repair webs, as applicable, of the 
aft pressure bulkhead, and applicable on-condition actions. We are 
proposing this AD to address the unsafe condition on these products.

DATES: We must receive comments on this proposed AD by September 25, 
2017.

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 NPRM, contact Boeing 
Commercial Airplanes, Attention: Contractual & Data Services (C&DS), 
2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740-5600; 
telephone 562-797-1717; Internet https://www.myboeingfleet.com. You may 
view this referenced service information at the FAA, Transport 
Standards Branch, 1601 Lind Avenue SW., Renton, WA. For information on 
the availability of this material at the FAA, call 425-227-

[[Page 37547]]

1221. It is also available on the Internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2017-
0766.

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-2017-
0766; 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: Lu Lu, Aerospace Engineer, Airframe 
Section, FAA, Seattle Aircraft Certification Office (ACO) Branch, 1601 
Lind Avenue SW., Renton, WA 98057-3356; phone: 425-917-6478; fax: 425-
917-6590; email: lu.lu@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-2017-0766; 
Product Identifier 2017-NM-046-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

    Fatigue damage can occur locally, in small areas or structural 
design details, or globally, in widespread areas. Multiple-site damage 
is widespread damage that occurs in a large structural element such as 
a single rivet line of a lap splice joining two large skin panels. 
Widespread 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. This condition is known as WFD. It is associated with general 
degradation of large areas of structure with similar structural details 
and stress levels. 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 ADs 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 reports of cracks in critical fastener rows of the 
gore web lap splices that are outside of the inspection area specified 
in AD 2012-18-13 R1, Amendment 39-17429 (78 FR 27020, May 9, 2013) 
(``AD 2012-18-13 R1''), which extends approximately 7 inches radially 
outboard from the center of the aft pressure bulkhead.
    Cracks in the critical lap splice fastener rows of the hidden 
forward gore web were found on airplanes with 37,000 to 66,000 total 
flight cycles. Cracks in the critical lap splice fastener rows of the 
visible aft gore web were also found on airplanes with 42,000 to 62,000 
total flight cycles. Cracking in the gore web lap splices of the aft 
pressure bulkhead could result in possible rapid decompression and loss 
of structural integrity of the airplane.

Related AD

    AD 2012-18-13 R1 requires repetitive inspections to detect cracking 
in the web of the aft pressure bulkhead at body station 1016 at the aft 
fastener row attachment to the ``Y'' chord, various inspections for 
discrepancies at the aft pressure bulkhead, and related investigative 
and corrective actions if necessary. The inspection areas of AD 2012-
18-13 R1 and the proposed inspections of this proposed AD are both 
related to the aft pressure bulkhead. However, this proposed AD would 
require separate inspections on a subset of the aft pressure bulkhead 
inspections required by AD 2012-18-13 R1.

Related Service Information Under 1 CFR Part 51

    We reviewed Boeing Alert Service Bulletin 737-53A1355, dated March 
10, 2017. The service information describes procedures for repetitive 
inspections of the gore web in Zone 1 (i.e., inspections around 
fastener locations in the gore web lap splices and around fastener 
locations in the apex area outside the gore web lap splices) and gore 
web lap splices in Zone 2 (i.e., inspections around fastener locations 
in the gore web lap splices) of the aft pressure bulkhead, and 
applicable on-condition actions. The service information also 
describes, for airplanes with an existing single gore web repair, 
procedures for repetitive inspections of the gore web (i.e., 
inspections around fastener locations in the gore web lap splices) and 
repair webs (i.e., inspections around fastener locations in the gore 
web lap splices and around fastener locations in the apex area outside 
the gore web lap splices); and, for airplanes with an existing all gore 
web repair, procedures for repetitive inspections of the repair webs 
(i.e., inspections around fastener locations in the repair gore web lap 
splices and around fastener locations in the apex area outside the 
repair gore web lap splices); and procedures for applicable on-
condition 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.

[[Page 37548]]

FAA's Determination

    We are proposing this AD because we evaluated all the relevant 
information and determined that 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 accomplishment of the actions 
identified as ``RC'' (required for compliance) in the Accomplishment 
Instructions of the service information described previously, except 
for differences between this proposed AD and the service information 
that are identified in the regulatory text of this proposed AD. For 
information on the procedures and compliance times, see this service 
information at http://www.regulations.gov by searching for and locating 
Docket No. FAA-2017-0766.

Difference Between Proposed AD and Service Bulletin

    Boeing Alert Service Bulletin 737-53A1355, dated March 10, 2017, 
specifies to contact the manufacturer for certain instructions, but 
this proposed AD would require using repair methods, modification 
deviations, and alteration deviations 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 281 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
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Inspection.............  46 work-hours x $85                 $0   $3,910 per inspection   $1,098,710 per
                          per hour = $3,910 per                    cycle.                  inspection cycle.
                          inspection cycle.
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    We estimate the following costs to do any necessary on-condition 
actions that would be required based on the results of the proposed 
inspection. We have no way of determining the number of aircraft that 
might need these on-condition actions:

                                               On-Condition Costs
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                                                                                                     Cost per
                    Action                                 Labor cost               Parts cost        product
----------------------------------------------------------------------------------------------------------------
Inspection of previous single gore web repair.  8 work-hours x $85 per hour =                 $0            $680
                                                 $680.
Inspection of previous all gore web repair....  10 work-hours x $85 per hour =                 0             850
                                                 $850.
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    We have received no definitive data that would enable us to provide 
cost estimates for the repairs 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.
    This proposed AD is issued in accordance with authority delegated 
by the Executive Director, Aircraft Certification Service, as 
authorized by FAA Order 8000.51C. In accordance with that order, 
issuance of ADs is normally a function of the Compliance and 
Airworthiness Division, but during this transition period, the 
Executive Director has delegated the authority to issue ADs applicable 
to transport category airplanes to the Director of the System Oversight 
Division.

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.

[[Page 37549]]

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-2017-0766; Product Identifier 
2017-NM-046-AD.

(a) Comments Due Date

    We must receive comments by September 25, 2017.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to all The Boeing Company Model 737-100, -200, -
200C, -300, -400, and -500 series airplanes, certificated in any 
category.

(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 (DAH) indicating that the gore web lap splices of the aft 
pressure bulkhead are subject to widespread fatigue damage (WFD). We 
are issuing this AD to detect and correct cracking in the gore webs, 
gore web lap splices, and repair webs of the aft pressure bulkhead, 
which could result in possible rapid decompression and loss of 
structural integrity.

(f) Compliance

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

(g) Required Actions for Group 1 Airplanes

    For airplanes identified as Group 1 in Boeing Alert Service 
Bulletin 737-53A1355, dated March 10, 2017: Within 120 days after 
the effective date of this AD, inspect the airplane, using a method 
approved in accordance with the procedures specified in paragraph 
(j) of this AD.

(h) Actions Required for Compliance

    Except as required by paragraph (i) of this AD: For airplanes 
identified as Group 2 in Boeing Alert Service Bulletin 737-53A1355, 
dated March 10, 2017, at the applicable times specified in paragraph 
1.E., ``Compliance,'' of Boeing Alert Service Bulletin 737-53A1355, 
dated March 10, 2017, do all applicable actions identified as 
required for compliance (``RC'') in, and in accordance with, the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1355, dated March 10, 2017.

(i) Exceptions to Service Information Specifications

    (1) Where paragraph 1.E., ``Compliance,'' of Boeing Alert 
Service Bulletin 737-53A1355, dated March 10, 2017, uses the phrase 
``after the original issue date of this service bulletin,'' for 
purposes of determining compliance with the requirements of this AD, 
the phrase ``after the effective date of this AD'' must be used.
    (2) Although Boeing Service Bulletin Boeing Alert Service 
Bulletin 737-53A1355, dated March 10, 2017, specifies to contact 
Boeing for repair instructions, and specifies that action as ``RC'' 
(Required for Compliance), this AD requires repair before further 
flight using a method approved in accordance with the procedures 
specified in paragraph (j) of this AD.

(j) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Los Angeles Aircraft Certification Office (ACO) 
Branch, 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 certification office, 
send it to the attention of the person identified in paragraph 
(k)(2) of this AD. Information may be emailed to: 9-ANM-LAACO-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, modification, or alteration required by this AD 
if it is approved by the Boeing Commercial Airplanes Organization 
Designation Authorization (ODA) that has been authorized by the 
Manager, Los Angeles ACO Branch, to make those findings. To be 
approved, the repair method, modification deviation, or alteration 
deviation must meet the certification basis of the airplane, and the 
approval must specifically refer to this AD.
    (4) Except as required by paragraph (i)(2) of this AD: For 
service information that contains steps that are labeled as Required 
for Compliance (RC), the provisions of paragraphs (j)(4)(i) and 
(j)(4)(ii) of this AD apply.
    (i) The steps labeled as RC, including substeps under an RC step 
and any figures identified in an RC step, must be done to comply 
with the AD. If a step or substep is labeled ``RC Exempt,'' then the 
RC requirement is removed from that step or substep. An AMOC is 
required for any deviations to RC steps, including substeps and 
identified figures.
    (ii) Steps not labeled as RC may be deviated from using accepted 
methods in accordance with the operator's maintenance or inspection 
program without obtaining approval of an AMOC, provided the RC 
steps, including substeps and identified figures, can still be done 
as specified, and the airplane can be put back in an airworthy 
condition.

(k) Related Information

    (1) For more information about this AD, contact Lu Lu, Aerospace 
Engineer, Airframe Section, FAA, Seattle Aircraft Certification 
Office (ACO) Branch, 1601 Lind Avenue SW., Renton, WA 98057-3356; 
phone: 425-917-6478; fax: 425-917-6590; email: lu.lu@faa.gov.
    (2) For information about AMOCs, contact George Garrido, 
Aerospace Engineer, Airframe Section, FAA, Los Angeles ACO Branch, 
3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: 562-627-
5232; fax: 562-627-5210; email: george.garrido@faa.gov.
    (3) For service information identified in this AD, contact 
Boeing Commercial Airplanes, Attention: Contractual & Data Services 
(C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740-
5600; telephone 562-797-1717; Internet https://www.myboeingfleet.com. You may view this referenced service 
information at the FAA, Transport Standards Branch, 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 July 26, 2017.
Jeffrey E. Duven,
Director, System Oversight Division, Aircraft Certification Service.
[FR Doc. 2017-16358 Filed 8-10-17; 8:45 am]
 BILLING CODE 4910-13-P


