
[Federal Register Volume 84, Number 36 (Friday, February 22, 2019)]
[Proposed Rules]
[Pages 5614-5617]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-02923]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2019-0022; Product Identifier 2018-NM-162-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 
airplanes. This proposed AD was prompted by reports of cracking in the 
lower lobe skin panel assemblies of the fuselage. This proposed AD 
would require replacement of lower lobe skin panel assemblies, and 
detailed inspections for scribe lines 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 April 8, 2019.

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, 2200 South 216th St., Des Moines, WA. For information 
on the availability of this material at the FAA, call 206-231-3195. It 
is also available on the internet at http://www.regulations.gov by 
searching for and locating Docket No. FAA-2019-0022.

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-2019-
0022; or in person at Docket Operations 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 Docket Operations (phone: 800-647-
5527) is in the ADDRESSES section. Comments will be available in the AD 
docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: James Guo, Aerospace Engineer, 
Airframe Section, FAA, Los Angeles ACO Branch, 3960 Paramount 
Boulevard, Lakewood, CA 90712-4137; phone: 562-627-5357; fax: 562-627-
5210; email: james.guo@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-2019-0022; 
Product Identifier 2018-NM-162-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 widespread fatigue damage (WFD). 
It is associated

[[Page 5615]]

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 737-300 
airplane reported a chem-milled step crack above stringer S-15 on the 
left side between station (STA) 360 and STA 380. The airplane had a lap 
splice modification done in accordance with Boeing Service Bulletin 
737-53A1177 and had logged 48,537 total flight cycles and 67,505 total 
flight hours. The 5-inch crack was found by visual inspection during 
airplane maintenance. On these skin panel assemblies, the bonded 
doubler is chemically milled to create pockets. At these locations, the 
loads could cause a condition where cracks could form along the 
longitudinal edges of the doubler at the step of the chem-milled 
pockets. Without skin panel assembly replacement, the skin cracks could 
grow and multiple adjacent cracks in the fuselage skin could link up 
with each other. This condition, if not addressed, could lead to 
decompression or loss of structural integrity of the airplane.

Related Service Information Under 1 CFR Part 51

    We reviewed Boeing Alert Requirements Bulletin 737-53A1379 RB, 
dated September 4, 2018. The service information describes procedures 
for replacement of lower lobe skin panel assemblies, and detailed 
inspections for scribe lines and 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.

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 in Boeing Alert Requirements Bulletin 737-53A1379 RB, dated 
September 4, 2018, 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-2019-0022.

Explanation of Requirements Bulletin

    The FAA worked in conjunction with industry, under the 
Airworthiness Directive Implementation Aviation Rulemaking Committee 
(AD ARC), to enhance the AD system. One enhancement is a process for 
annotating which steps in the service information are ``required for 
compliance'' (RC) with an AD. Boeing has implemented this RC concept 
into Boeing service bulletins.
    In an effort to further improve the quality of ADs and AD-related 
Boeing service information, a joint process improvement initiative was 
worked between the FAA and Boeing. The initiative resulted in the 
development of a new process in which the service information more 
clearly identifies the actions needed to address the unsafe condition 
in the ``Accomplishment Instructions.'' The new process results in a 
Boeing Requirements Bulletin, which contains only the actions needed to 
address the unsafe condition (i.e., only the RC actions).

Explanation of Compliance Time

    The compliance time for the modification 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 171 airplanes of U.S. 
registry. We estimate the following costs to comply with this proposed 
AD:

                                                         Estimated Costs for Required Actions *
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                        Cost per
                Action                          Labor cost            Parts cost        product                     Cost on U.S. operators
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Inspection and replacement............  688 work-hours x $85 per              (*)          $58,480   $10,000,080
                                         hour = $58,480.
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Parts cost unavailable.


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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 and associated appliances 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-2019-0022; Product Identifier 
2018-NM-162-AD.

(a) Comments Due Date

    We must receive comments by April 8, 2019.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to The Boeing Company Model 737-200, -200C, -
300, -400, and -500 airplanes, certificated in any category, as 
identified in Boeing Alert Requirements Bulletin 737-53A1379 RB, 
dated September 4, 2018.

(d) Subject

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

(e) Unsafe Condition

    This AD was prompted by reports of cracking in the lower lobe 
skin panel assemblies of the fuselage. We are issuing this AD to 
address the possibility of multiple adjacent cracks at chem-milled 
steps in the fuselage skin linking up with each other, which could 
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 specified by paragraph (h) of this AD: At the 
applicable times specified in the ``Compliance'' paragraph of Boeing 
Alert Requirements Bulletin 737-53A1379 RB, dated September 4, 2018, 
do all applicable actions identified in, and in accordance with, the 
Accomplishment Instructions of Boeing Alert Requirements Bulletin 
737-53A1379 RB, dated September 4, 2018.

    Note 1 to paragraph (g) of this AD: Guidance for accomplishing 
the actions required by this AD can be found in Boeing Alert Service 
Bulletin 737-53A1379, dated September 4, 2018, which is referred to 
in Boeing Alert Requirements Bulletin 737-53A1379 RB, dated 
September 4, 2018.

(h) Exceptions to Service Information Specifications

    (1) For purposes of determining compliance with the requirements 
of this AD: Where Boeing Alert Requirements Bulletin 737-53A1379 RB, 
dated September 4, 2018, uses the phrase ``the original issue date 
of Requirements Bulletin 737-53A1379 RB,'' this AD requires using 
``the effective date of this AD.''
    (2) Where Boeing Alert Requirements Bulletin 737-53A1379 RB, 
dated September 4, 2018, specifies contacting Boeing for work 
instructions or for scribe line repair and skin panel replacement 
work instructions: This AD requires doing the work and the scribe 
line repair and skin panel replacement before further flight using a 
method approved in accordance with the procedures specified in 
paragraph (i) of this AD.

(i) 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 (j)(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, FAA, 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.

(j) Related Information

    (1) For more information about this AD, contact James Guo, 
Aerospace Engineer, Airframe Section, FAA, Los Angeles ACO Branch, 
3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: 562-627-
5357; fax: 562-627-5210; email: james.guo@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,

[[Page 5617]]

Transport Standards Branch, 2200 South 216th St., Des Moines, WA. 
For information on the availability of this material at the FAA, 
call 206-231-3195.

    Issued in Des Moines, Washington, on February 8, 2019.
Michael Kaszycki,
Acting Director, System Oversight Division, Aircraft Certification 
Service.
[FR Doc. 2019-02923 Filed 2-21-19; 8:45 am]
BILLING CODE 4910-13-P


