[Federal Register Volume 85, Number 184 (Tuesday, September 22, 2020)]
[Proposed Rules]
[Pages 59449-59451]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-20657]



[[Page 59449]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0844; Product Identifier 2020-NM-100-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 737-100, -200, -200C, -300, -400, and 
-500 series airplanes. This proposed AD was prompted by a report of 
cracks found in fastener holes at a certain station of the center wing 
box. This proposed AD would require repetitive external surface high 
frequency eddy current inspections (HFEC) and repetitive external 
surface ultrasonic inspections; or repetitive internal detailed 
inspections; of a certain station of the center wing box for any 
cracking, and repair if necessary. 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 November 6, 
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. You may 
view this referenced service information at the FAA, Airworthiness 
Products Section, Operational Safety 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-
0844.

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-
0844; 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, 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; 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-2020-0844; 
Product Identifier 2020-NM-100-AD'' at the beginning of your comments. 
The most helpful comments reference a specific portion of the proposal, 
explain the reason for any recommended change, and include supporting 
data. The FAA will consider all comments received by the closing date 
and may amend this proposal because of those comments.
    Except for Confidential Business Information (CBI) as described in 
the following paragraph, and other information as described in 14 CFR 
11.35, the FAA will post all comments received, without change, to 
https://www.regulations.gov, including any personal information you 
provide. The agency will also post a report summarizing each 
substantive verbal contact received about this proposed AD.

Confidential Business Information

    CBI is commercial or financial information that is both customarily 
and actually treated as private by its owner. Under the Freedom of 
Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public 
disclosure. If your comments responsive to this NPRM contain commercial 
or financial information that is customarily treated as private, that 
you actually treat as private, and that is relevant or responsive to 
this NPRM, it is important that you clearly designate the submitted 
comments as CBI. Please mark each page of your submission containing 
CBI as ``PROPIN.'' The FAA will treat such marked submissions as 
confidential under the FOIA, and they will not be placed in the public 
docket of this NPRM. Submissions containing CBI should be sent to Wayne 
Ha, Aerospace Engineer, Airframe Section, FAA, Los Angeles ACO Branch, 
3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: 562-627-5238; 
email: [email protected]. Any commentary that the FAA receives which is 
not specifically designated as CBI will be placed in the public docket 
for this rulemaking.

Discussion

    The FAA has received a report of cracks found in fastener holes at 
the center wing box, station 663.75 rear spar, of the lower skin 
located at left buttock line 6.50. The lower skin cracks were hidden 
between the center wing box lower chord on the upper surface and the 
keel beam upper chord on the lower surface. A crack in the center wing 
box, rear spar lower skin, or lower chord could go undetected. This 
condition, if not addressed, could result in inability of a principal 
structural element to sustain limit load and could adversely affect the 
structural integrity of the airplane.

Explanation of Applicability

    The Boeing Company Model 737 airplanes having line numbers 1 
through 291 have a limit of validity (LOV) of 34,000 total flight 
cycles, and the actions proposed in this NPRM, as specified in Boeing 
Alert Requirements Bulletin 737-57A1348 RB, dated June 1, 2020, would 
be required at a compliance time occurring after that LOV. Although 
operation of an airplane beyond its LOV is prohibited by 14 CFR 
121.1115 and 129.115, this NPRM would include those airplanes in the 
applicability so that these airplanes are tracked in the event the LOV 
is extended in the future.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Boeing Alert Requirements Bulletin 737-57A1348 RB, 
dated June 1, 2020. The service information describes procedures for 
repetitive external surface HFEC inspections and repetitive external 
surface ultrasonic inspections; or repetitive internal detailed 
inspections; of the center wing box, station 663.75 rear spar, lower 
skin, and lower chord

[[Page 59450]]

between left buttock line 31.83 and right buttock line 31.83, for any 
cracking, and repair if necessary.
    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 737-57A1348 RB, dated 
June 1, 2020, 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-2020-0844.

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 141 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
----------------------------------------------------------------------------------------------------------------
Repetitive external HFEC and       3 work-hours x $85             $0  $255 per inspection   Up to $35,955 per
 external ultrasonic inspections.   per hour = $255 per                cycle.                inspection cycle.
                                    inspection cycle.
Repetitive internal detailed       28 work-hours x $85            $0  $2,380 per            Up to $335,580 per
 inspections.                       per hour = $2,380                  inspection cycle.     inspection cycle.
                                    per inspection
                                    cycle.
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    The FAA has received no definitive data that would enable providing 
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.
    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-2020-0844; Product Identifier 
2020-NM-100-AD.

(a) Comments Due Date

    The FAA must receive comments by November 6, 2020.

(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 57, Wings.

(e) Unsafe Condition

    This AD was prompted by a report of cracks found in fastener 
holes at the center wing box, station 663.75 rear spar, of the

[[Page 59451]]

lower skin located at left buttock line 6.50. The FAA is issuing 
this AD to address such cracking, which could result in inability of 
a principal structural element to sustain 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) Actions for Group 1

    For airplanes identified as Group 1 in Boeing Alert Requirements 
Bulletin 737-57A1348 RB, dated June 1, 2020: Within 120 days after 
the effective date of this AD, inspect the airplane and do all 
applicable on-condition actions using a method approved in 
accordance with the procedures specified in paragraph (j) of this 
AD.

(h) Required Actions

    For airplanes identified as Group 2 in Boeing Alert Requirements 
Bulletin 737-57A1348 RB, dated June 1, 2020, except as specified by 
paragraph (i) of this AD: At the applicable times specified in the 
``Compliance'' paragraph of Boeing Alert Requirements Bulletin 737-
57A1348 RB, dated June 1, 2020, do all applicable actions identified 
in, and in accordance with, the Accomplishment Instructions of 
Boeing Alert Requirements Bulletin 737-57A1348 RB, dated June 1, 
2020.

    Note 1 to paragraph (h): Guidance for accomplishing the actions 
required by this AD can be found in Boeing Alert Service Bulletin 
737-57A1348, dated June 1, 2020, which is referred to in Boeing 
Alert Requirements Bulletin 737-57A1348 RB, dated June 1, 2020.

(i) Exceptions to Service Information Specifications

    (1) Where Boeing Alert Requirements Bulletin 737-57A1348 RB, 
dated June 1, 2020, uses the phrase ``the original issue date of 
Requirements Bulletin 737-57A1348 RB,'' this AD requires using ``the 
effective date of this AD,'' except where Boeing Alert Requirements 
Bulletin 737-57A1348 RB, dated June 1, 2020, uses the phrase ``the 
original issue date of Requirements Bulletin 737-57A1348 RB'' in a 
note or flag note.
    (2) Where Boeing Alert Requirements Bulletin 737-57A1348 RB, 
dated June 1, 2020, specifies contacting Boeing for repair 
instructions: This AD requires doing the repair 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 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: [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 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 Wayne Ha, 
Aerospace Engineer, Airframe Section, FAA, Los Angeles ACO Branch, 
3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: 562-627-
5238; 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, Airworthiness Products Section, Operational 
Safety 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 September 11, 2020.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2020-20657 Filed 9-21-20; 8:45 am]
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