[Federal Register Volume 85, Number 32 (Tuesday, February 18, 2020)]
[Proposed Rules]
[Pages 8776-8779]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-03083]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0097; Product Identifier 2019-NM-208-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 all The Boeing Company Model 737-300, -400, and -500 series 
airplanes. This proposed AD was prompted by a report that a crack 
indication consistent with fatigue cracking was found on the left 
nacelle support overwing fitting flange fastener hole during teardown 
of a Model 737-300 series airplane. This proposed AD would require a 
general visual inspection of the strut to wing diagonal brace at a 
certain location for cracking. For certain airplanes, this proposed AD 
would also require an ultrasonic inspection of certain fasteners of the 
nacelle support overwing fitting at a certain location for cracking. 
For certain other airplanes, this proposed AD would also require a 
magnetic check of the nacelle support overwing fitting at a certain 
location to determine the material composition. This proposed AD would 
also require 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 April 3, 
2020.

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 https://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 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 https://www.regulations.gov by 
searching for and locating Docket No. FAA-2020-0097.

[[Page 8777]]

Examining the AD Docket

    You may examine the AD docket on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2020-
0097; 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: Wayne Ha, Aerospace Engineer, Airframe 
Section, FAA, Los Angeles ACO Branch, 3960 Paramount Boulevard, 
Lakewood, CA 90712-4137; phone: 562-627-5238; fax: 562-627-5210; email: 
[email protected].

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-2020-0097; 
Product Identifier 2019-NM-208-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, without change, to https://www.regulations.gov, including any personal information you provide. 
The FAA will also post a report summarizing each substantive verbal 
contact the agency receives about this proposed AD.

Discussion

    The FAA has received a report indicating that a crack indication 
consistent with fatigue cracking was found on the left nacelle support 
overwing fitting flange fastener hole during teardown of a Model 737-
300 series airplane. Further analysis determined the root cause of the 
crack is stress at the first two forward fasteners of the nacelle 
support overwing fitting being higher than anticipated. Existing 
maintenance planning document (MPD) inspections do not provide 
opportunities to detect a failed nacelle support overwing fitting at 
wing buttock line (WBL) 191. The crack finding occurred at 67,695 total 
flight cycles and 80,269 total flight hours. This condition, if not 
addressed, could result in an undetected crack in the nacelle support 
overwing fittings or strut to wing diagonal brace, which could result 
in the inability of the structure to carry limit load and could 
adversely affect the structural integrity of the airplane.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Boeing Alert Requirements Bulletin 737-57A1345 RB, 
dated December 17, 2019. This service information describes procedures 
for a magnetic check to determine material composition of the nacelle 
support overwing fitting at WBL 191; ultrasonic inspections of the 
nacelle support overwing fitting at WBL 191 for cracking; general 
visual inspections of the strut to wing diagonal brace at nacelle 
station (STA) 278 for cracking; and applicable on-condition actions. 
On-condition actions include repetitive ultrasonic inspections of the 
nacelle support overwing fitting at WBL 191 for cracking, repetitive 
general visual inspections of the strut to wing diagonal brace at 
nacelle STA 278 for cracking, 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 FAA 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 737-57A1345 RB, dated 
December 17, 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 https://www.regulations.gov by searching for and 
locating Docket No. FAA-2020-0097.

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).

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 per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Magnetic Check........................  1 work-hour x $85 per                 $0             $85         $13,430
                                         hour = $85.
Ultrasonic Inspection.................  5 work-hours x $85 per                 0             425          67,150
                                         hour = $425.
General Visual Inspection.............  1 work-hour x $85 per                  0              85          13,430
                                         hour = $85.
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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 
inspections:

[[Page 8778]]



                                   Estimated Costs of On-Condition Inspections
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                                                                                                 Cost on U.S.
              Action                    Labor cost        Parts cost      Cost per product        operators
----------------------------------------------------------------------------------------------------------------
Ultrasonic Inspections...........  5 work-hours x $85               $0  $425 per inspection  $67,150 per
                                    per hour = $425                      cycle.               inspection cycle.
                                    per inspection
                                    cycle.
General Visual Inspections.......  1 work-hour x $85                 0  $85 per inspection   $13,430 per
                                    per hour = $85 per                   cycle.               inspection cycle.
                                    inspection cycle.
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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.

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:

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-2020-0097; Product Identifier 
2019-NM-208-AD.

(a) Comments Due Date

    The FAA must receive comments by April 3, 2020.

(b) Affected ADs

    None.

(c) Applicability

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

(d) Subject

    Air Transport Association (ATA) of America Code 57, Wings.

(e) Unsafe Condition

    This AD was prompted by a report that a crack indication 
consistent with fatigue cracking was found on the left nacelle 
support overwing fitting flange fastener hole during teardown of a 
Model 737-300 series airplane. The FAA is issuing this AD to address 
the potential for undetected cracks in the nacelle support overwing 
fittings or strut to wing diagonal brace, which could result in the 
inability of the structure to carry limit load and could adversely 
affect the 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 737-57A1345 RB, dated December 17, 2019, 
do all applicable actions identified in, and in accordance with, the 
Accomplishment Instructions of Boeing Alert Requirements Bulletin 
737-57A1345 RB, dated December 17, 2019. Actions identified as 
terminating actions in Boeing Alert Requirements Bulletin 737-
57A1345 RB, dated December 17, 2019, terminate the applicable 
required actions of this AD, provided the terminating action is done 
in accordance with the Accomplishment Instructions of Boeing Alert 
Requirements Bulletin 737-57A1345 RB, dated December 17, 2019.

    Note 1 to paragraph (g): Guidance for accomplishing the actions 
required by this AD can be found in Boeing Alert Service Bulletin 
737-57A1345, dated December 17, 2019, which is referred to in Boeing 
Alert Requirements Bulletin 737-57A1345 RB, dated December 17, 2019.

(h) Exceptions to Service Information Specifications

    (1) Where Boeing Alert Requirements Bulletin 737-57A1345 RB, 
dated December 17, 2019, uses the phrase ``the original issue date 
of Requirements Bulletin (RB) 737-57A1345 RB,'' this AD requires 
using ``the effective date of this AD.''
    (2) Where Boeing Alert Requirements Bulletin 737-57A1345 RB, 
dated December 17, 2019, specifies contacting Boeing for repair 
instructions: This AD requires doing the repair 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: [email protected].
    (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

[[Page 8779]]

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 Wayne Ha, 
Aerospace Engineer, Airframe Section, FAA, Los Angeles ACO Branch, 
3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: 562-627-
5238; fax: 562-627-5210; email: [email protected].
    (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, 2200 South 216th 
St., Des Moines, WA. For information on the availability of this 
material at the FAA, call 206-231-3195.

    Issued on February 11, 2020.
Gaetano A. Sciortino,
Deputy Director for Strategic Initiatives, Compliance & Airworthiness 
Division, Aircraft Certification Service.
[FR Doc. 2020-03083 Filed 2-14-20; 8:45 am]
BILLING CODE 4910-13-P