
[Federal Register Volume 82, Number 153 (Thursday, August 10, 2017)]
[Proposed Rules]
[Pages 37366-37369]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-16355]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-0715; Product Identifier 2017-NM-073-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 737-200, -200C, -300, -400, and -500 
series airplanes. This AD was prompted by an evaluation by the design 
approval holder (DAH) indicating that the fuselage crown skin panels 
are subject to widespread fatigue damage (WFD). This proposed AD would 
require repetitive inspections, replacement, and applicable on-
condition actions for certain fuselage crown skin panels. We are 
proposing this AD to address the unsafe condition on these products.

[[Page 37367]]


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 425-227-1221. It is 
also available on the Internet at http://www.regulations.gov by 
searching for and locating Docket No. FAA-2017-0715.

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-
0715; 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 NPRM, 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: Jennifer Tsakoumakis, Aerospace 
Engineer, Airframe Section, FAA, Los Angeles Aircraft Certification 
Office (ACO) Branch, 3960 Paramount Boulevard, Lakewood, CA 90712-4137; 
phone: 562-627-5264; fax: 562-627-5210; email: 
Jennifer.tsakoumakis@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-2017-0715; 
Product Identifier 2017-NM-073-AD'' at the beginning of your comments. 
We specifically invite comments on the overall regulatory, economic, 
environmental, and energy aspects of this NPRM. We will consider all 
comments received by the closing date and may amend this NPRM 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 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 a report indicating that an operator of a Model 
737-300 series airplane reported multiple cracks of the chem-milled 
steps in adjacent bays of the fuselage crown skin. These cracks were 
discovered by visual inspection 855 flight cycles after the most recent 
detailed inspection. The initial visual inspection revealed three 
cracks varying in length from 1.8 inches to 8.5 inches. Further 
inspection using ultrasonic phased array revealed nine additional 
subsurface cracks. The airplane had 55,232 total flight cycles. 
Multiple adjacent cracks in the fuselage crown skin panels, if not 
detected and corrected, could link up and lead to decompression or loss 
of structural integrity of the airplane.

Related Service Information Under 1 CFR Part 51

    We reviewed Boeing Alert Service Bulletin 737-53A1358, dated April 
27, 2017. The service information describes procedures for repetitive 
inspections, replacement, and applicable on-condition actions for 
certain fuselage crown skin panels. 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.

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 accomplishment of the actions 
identified as ``RC'' (required for compliance) in the Accomplishment 
Instructions of Boeing Alert Service

[[Page 37368]]

Bulletin 737-53A1358, dated April 27, 2017, described previously, 
except for any differences identified as exceptions 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-2017-0715.

Explanation of Compliance Time

    The compliance time for the replacement specified in this proposed 
AD for addressing WFD was established to ensure that discrepant 
structure is replaced before WFD develops in airplanes. Standard 
inspection techniques cannot be relied on to detect WFD before it 
becomes a hazard to flight. We will not grant any extensions of the 
compliance time to complete any AD-mandated service bulletin related to 
WFD without extensive new data that would substantiate and clearly 
warrant such an extension.

Costs of Compliance

    We estimate that this proposed AD affects 200 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
----------------------------------------------------------------------------------------------------------------
Inspection........................  Up to 507 work-hours          $0  Up to $43,095 per     Up to $8,619,000 per
                                     x $85 per hour =                  inspection cycle.     inspection cycle.
                                     $43,095 per
                                     inspection cycle.
Replacement.......................  304 work-hours x $85      95,000  $120,840 per skin     Up to $24,168,000.
                                     per hour = $25,840                panel.
                                     per skin panel.
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    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.
    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.


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-2017-0715; Product Identifier 
2017-NM-073-AD.

(a) Comments Due Date

    We must receive comments by September 25, 2017.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to The Boeing Company Model 737-200, -200C, -
300, -400, and -500 series airplanes, certificated in any category, 
as identified in Boeing Alert Service Bulletin 737-53A1358, dated 
April 27, 2017.

(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 fuselage crown skin panels are subject to 
widespread fatigue damage. We are issuing this AD to detect and 
correct cracking in the fuselage crown skin panels. Multiple 
adjacent cracks in the fuselage crown skin could link up and lead to 
decompression or loss of structural integrity of the airplane.

(f) Compliance

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

(g) Required Actions

    Except as required by paragraph (h) of this AD: At the 
applicable times specified in paragraph 1.E., ``Compliance,'' of 
Boeing Alert Service Bulletin 737-53A1358, dated April 27, 2017, do 
all applicable actions identified as ``RC'' (required for 
compliance) in, and in accordance with, the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1358, dated 
April 27, 2017.

[[Page 37369]]

(h) Exceptions to Service Information Specifications

    (1) For purposes of determining compliance with the requirements 
of this AD, the phrase ``the effective date of this AD'' may be 
substituted for ``the original issue date of this service 
bulletin,'' as specified in Boeing Alert Service Bulletin 737-
53A1358, dated April 27, 2017.
    (2) Where Boeing Alert Service Bulletin 737-53A1358, dated April 
27, 2017, specifies contacting Boeing, and specifies that action as 
RC: This AD requires using a method approved in accordance with the 
procedures specified in paragraph (j) of this AD.
    (3) Part 7 of Boeing Alert Service Bulletin 737-53A1358, dated 
April 27, 2017, specifies post-modification airworthiness limitation 
inspections in compliance with 14 CFR 25.571(a)(3) at the modified 
locations to support compliance with 14 CFR 121.1109(c)(2) or 
129.109(b)(2). Although Part 7 is identified as RC, this AD does not 
require accomplishment of Part 7. As airworthiness limitations, 
these inspections are required by maintenance and operational rules. 
It is therefore unnecessary to mandate them in this AD. Deviations 
from these inspections require FAA approval, but do not require 
approval of an alternative method of compliance.

(i) Terminating Action for Repetitive Inspections

    (1) Replacement of a skin panel, in accordance with Part 8 of 
the Accomplishment Instructions of Boeing Alert Service Bulletin 
737-53A1358, dated April 27, 2017, except as required by paragraph 
(h)(2) of this AD, terminates the actions specified in Parts 1, 4, 
and 6 of the Accomplishment Instructions of Boeing Alert Service 
Bulletin 737-53A1358, dated April 27, 2017, as required by paragraph 
(g) of this AD, for that replaced skin panel only. To be acceptable 
as terminating action, the replacement may not be done prior to the 
applicable time specified in Table 4 of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1358, dated 
April 27, 2017.
    (2) Completion of a structural repair manual repair to repair 
cracking, in accordance with Part 2 of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1358, dated 
April 27, 2017, except as required by paragraph (h)(2) of this AD, 
terminates the repetitive inspections specified in Part 1 of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1358, dated April 27, 2017, as required by paragraph (g) of this 
AD, for that repair location only.
    (3) Completion of a ``Category C repair'' to repair cracking, in 
accordance with Part 3 of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 737-53A1358, dated April 27, 2017, except as 
required by paragraph (h)(2) of this AD, terminates the repetitive 
inspections specified in Part 1 of the Accomplishment Instructions 
of Boeing Alert Service Bulletin 737-53A1358, dated April 27, 2017, 
as required by paragraph (g) of this AD, for that repair location 
only.
    (4) Completion of a ``Change Category C Repair to SB Repair,'' 
in accordance with Part 6 of the Accomplishment Instructions of 
Boeing Alert Service Bulletin 737-53A1358, dated April 27, 2017, 
except as required by paragraph (h)(2) of this AD, terminates the 
inspections specified in Part 4 of the Accomplishment Instructions 
of Boeing Alert Service Bulletin 737-53A1358, dated April 27, 2017, 
as required by paragraph (g) of this AD, for that repair location 
only.

(j) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Los Angeles 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)(1) of this AD. Information 
may be emailed to: 9-ANM-LAACO-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 paragraphs (h)(2) and (h)(3) of this 
AD: For service information that contains steps that are labeled as 
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 Jennifer 
Tsakoumakis, Aerospace Engineer, Airframe Section, FAA, Los Angeles 
ACO Branch, 3960 Paramount Boulevard, Lakewood, CA 90712-4137; 
phone: 562-627-5264; fax: 562-627-5210; email: 
Jennifer.tsakoumakis@faa.gov.
    (2) 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. 2017-16355 Filed 8-9-17; 8:45 am]
 BILLING CODE 4910-13-P


