Document ID: FAA-2019-0670-0001
Agency: faa
Document Type: Proposed Rule
Title: Airworthiness Directives; The Boeing Company Airplanes
Posted Date: 2019-09-04T04:00Z

[Federal Register Volume 84, Number 171 (Wednesday, September 4, 2019)]
[Proposed Rules]
[Pages 46496-46498]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-18980]

[[Page 46496]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2019-0670; Product Identifier 2019-NM-104-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: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain The Boeing Company Model 737-200, -200C, -300, -400, and -
500 series airplanes. This proposed AD was prompted by an evaluation by 
the design approval holder (DAH) indicating that the lower skin of the 
fuselage skin lap splices along the lower fastener row of a certain 
stringer lap splice on certain body station skin panels is subject to 
widespread fatigue damage (WFD). This proposed AD would require 
inspections of the lower skin of the fuselage skin lap splices along 
the lower fastener row of a lap splice on certain body station skin 
panels and applicable on-condition actions. The FAA is proposing this 
AD to address the unsafe condition on these products.

DATES: The FAA must receive comments on this proposed AD by October 21, 
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; phone: 
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-2019-0670.

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-
0670; 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 is listed above. 
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

    The FAA invites 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-2019-0670; 
Product Identifier 2019-NM-104-AD'' at the beginning of your comments. 
The FAA specifically invites comments on the overall regulatory, 
economic, environmental, and energy aspects of this NPRM. The FAA will 
consider all comments received by the closing date and may amend this 
NPRM because of those comments.
    The FAA will post all comments received, without change, to http://www.regulations.gov, including any personal information you provide. 
The FAA will also post a report summarizing each substantive verbal 
contacts received 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.
    The FAA has received a report indicating that an operator of a 
Model 737-300 airplane discovered a crack in the skin at a chem-milled 
step at body station (STA) 727B+10, just above stringer (S)-14R. The 
airplane had accumulated 88,805 flight hours and 65,804 flight cycles 
at the time the crack was found. Upon further inspection in the local 
area using high frequency eddy current (HFEC) hole probe inspection, 
multiple fastener hole cracks were

[[Page 46497]]

found in the S-14 lap splice lower row in the lower skin between STA 
727A and STA 727E. The lower skin at S-14 is structure that may be 
susceptible to WFD and may also have scratches that can propagate into 
cracks. The scratch cracks may interact with fatigue cracking. This 
condition, if not addressed, could result in rapid decompression or 
loss of structural integrity of the airplane.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Boeing Alert Requirements Bulletin 737-53A1382 RB, 
dated May 6, 2019. The service information describes procedures for 
detailed inspections for previous repairs, and repetitive dual 
frequency eddy current (DFEC) inspections for cracks of the lower skin 
of the fuselage skin lap splices along the lower fastener row of the S-
14 lap splice at specified locations on the STA 727 to STA 908 skin 
panel in areas not inspected by other service bulletins, and applicable 
on-condition actions. On-condition actions include open hole HFEC 
inspections for cracks, and repair.
    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

    The FAA is proposing this AD because the agency 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 737-53A1382 RB, dated 
May 6, 2019, 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-2019-0670.

Costs of Compliance

    The FAA estimates that this proposed AD affects 158 airplanes of 
U.S. registry. The FAA estimates the following costs to comply with 
this proposed AD:

                                      Estimated Costs for Required Actions
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                                                                                                 Cost on U.S.
              Action                    Labor cost        Parts cost      Cost per product        operators
----------------------------------------------------------------------------------------------------------------
DFEC Inspections of S-14 Lap       18 work-hours x $85              $0  $1,530 per           $241,740 per
 Splices.                           per hour = $1,530                    inspection.          inspection.
                                    per inspection.
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    The FAA estimates the following costs to do any necessary on-
condition inspections that would be required. The FAA has no way of 
determining the number of aircraft that might need these on-condition 
actions:

                 Estimated Costs of On-Condition Actions
------------------------------------------------------------------------
            Labor cost                Parts cost      Cost per product
------------------------------------------------------------------------
97 work-hours x $85 per hour =                  $0  $8,245
 $8,245.
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    The FAA has received no definitive data that would enable us to 
provide cost estimates for the on-condition 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.
    The FAA is 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

    The FAA 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. Will not affect intrastate aviation in Alaska, and
    3. 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:

[[Page 46498]]

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-2019-0670; Product Identifier 
2019-NM-104-AD.

(a) Comments Due Date

    The FAA must receive comments by October 21, 2019.

(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 Requirements Bulletin 737-53A1382 RB, 
dated May 6, 2019.

(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 lower skin of the fuselage skin lap 
splices along the lower fastener row of the stringer (S)-14 lap 
splice on certain body station skin panels is subject to widespread 
fatigue damage (WFD). The FAA is issuing this AD to address scratch 
cracks and fatigue cracking which may interact and could result in 
rapid 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 737-53A1382 RB, dated May 6, 2019, do 
all applicable actions identified in, and in accordance with, the 
Accomplishment Instructions of Boeing Alert Requirements Bulletin 
737-53A1382 RB, dated May 6, 2019.

    Note 1 to paragraph (g): Guidance for accomplishing the actions 
required by this AD can be found in Boeing Alert Service Bulletin 
737-53A1382, dated May 6, 2019, which is referred to in Boeing Alert 
Requirements Bulletin 737-53A1382 RB, dated May 6, 2019.

(h) Exceptions to Service Information Specifications

    (1) For purposes of determining compliance with the requirements 
of this AD: Where Boeing Alert Requirements Bulletin 737-53A1382 RB, 
dated May 6, 2019 uses the phrase ``the original issue date of 
Requirements Bulletin 737-53A1382 RB,'' this AD requires using ``the 
effective date of this AD.''
    (2) Where Boeing Alert Requirements Bulletin 737-53A1382 RB, 
dated May 6, 2019, specifies contacting Boeing for repair 
instructions or for alternative inspections: This AD requires doing 
the repair, or doing the alternative inspections and applicable on-
condition actions using a method approved in accordance with the 
procedures specified in paragraph (j) of this AD.

(i) Terminating Action

    Certain skin panel replacements identified as terminating action 
in Boeing Alert Requirements Bulletin 737-53A1382 RB, dated May 6, 
2019, terminate the inspections in the corresponding locations 
required by this AD.

(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 Company 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.

(k) 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; phone: 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.

    Issued in Des Moines, Washington, on August 23, 2019.
Suzanne Masterson,
Acting Director, System Oversight Division, Aircraft Certification 
Service.
[FR Doc. 2019-18980 Filed 9-3-19; 8:45 am]
BILLING CODE 4910-13-P