[Federal Register Volume 85, Number 159 (Monday, August 17, 2020)]
[Proposed Rules]
[Pages 49978-49981]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-17837]


 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
 
 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
 ========================================================================
 

  Federal Register / Vol. 85, No. 159 / Monday, August 17, 2020 / 
Proposed Rules  

[[Page 49978]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0689; Product Identifier 2020-NM-060-AD]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: The FAA proposes to supersede Airworthiness Directive (AD) 
2013-18-08, which applies to certain The Boeing Company Model 737-200, 
-200C, -300, -400, and -500 series airplanes. AD 2013-18-08 requires 
repetitive inspections for cracking of certain upper and lower skin 
panels of the fuselage, and of the fuselage skin along certain chem-
milled lines, and corrective actions if necessary. AD 2013-18-08 also 
includes a terminating action for the repetitive inspections of certain 
modified or repaired areas only. Since the FAA issued AD 2013-18-08, 
there have been reports of additional cracking in certain horizontal 
and vertical chem-milled step locations outside of those identified in 
AD 2013-18-08. This proposed AD would continue to require repetitive 
inspections for cracking of the fuselage skin along certain chem-milled 
lines and applicable on-condition actions, and would expand the 
inspection area. This AD would continue to provide terminating action 
for repetitive inspections of certain modified or repaired areas. This 
proposed AD would also add airplanes to the applicability. 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 1, 
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 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-
0689.

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-
0689; 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: 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-2020-0689; 
Product Identifier 2020-NM-060-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 NPRM 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 FAA will also post a report summarizing each substantive 
verbal contact received about this proposed AD.

Confidential Business Information

    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 the person identified in the FOR FURTHER 
INFORMATION CONTACT section. Any commentary that the FAA receives which 
is not specifically designated as CBI will be placed in the public 
docket for this rulemaking.

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

[[Page 49979]]

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 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 ADs 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 issued AD 2013-18-08, Amendment 39-17581 (78 FR 60660, 
October 2, 2013) (``AD 2013-18-08''), for certain The Boeing Company 
Model 737-200, -200C, -300, -400, and -500 series airplanes. AD 2013-
18-08 requires repetitive inspections for cracking of certain upper and 
lower skin panels of the fuselage, and of the fuselage skin along 
certain chem-milled lines, and corrective actions if necessary. AD 
2013-18-08 also includes a terminating action for the repetitive 
inspections of certain modified or repaired areas only. The FAA issued 
AD 2013-18-08 to address fatigue cracking of the skin panels, which 
could result in sudden fracture and failure of the skin panels of the 
fuselage, and consequent rapid decompression of the airplane.

Actions Since AD 2013-18-08 Was Issued

    Since the FAA issued AD 2013-18-08, there have been reports of 
additional cracking in the horizontal and vertical chem-milled step 
locations outside of those identified in AD 2013-18-08. The cracking 
was caused by fatigue from hoop stress and higher than expected bending 
stresses across the chem-milled steps. The FAA has determined that the 
repetitive inspections must be expanded to include these areas and that 
additional airplanes are subject to the unsafe condition.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Boeing Alert Service Bulletin 737-53A1346, dated 
March 27, 2020. This service information describes procedures for 
repetitive detailed and non-destructive tests (NDTs) (including 
external medium frequency eddy current (MFEC), external magneto optical 
imaging (MOI), external c-scan, external sliding probe, external high 
frequency eddy current (HFEC), external low frequency eddy current 
(LFEC), internal ultrasonic phased array (UTPA), or internal 
ultrasonic); inspections for cracking of the fuselage skin along all 
horizontal and vertical chem-milled locations with a history of 
cracking between stations (STAs) 259.5 and 1016; and applicable on-
condition actions. On-condition actions include repair; LFEC 
inspections of certain repairs for cracking; detailed inspections of 
certain repairs for cracking and loose, missing, or damaged fasteners; 
replacement of loose, missing, or damaged fasteners; and preventative 
modifications. 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

    Although this proposed AD does not explicitly restate the 
requirements of AD 2013-18-08, this proposed AD would retain certain 
requirements of AD 2013-18-08. Those requirements are referenced in the 
service information identified previously, which, in turn, is 
referenced in paragraph (g) of this proposed AD. This proposed AD would 
expand the area for the existing inspections for cracking of the 
fuselage skin along all horizontal and vertical chem-milled locations 
and add airplanes to the applicability. This proposed AD would also 
require accomplishment of the actions identified as ``RC'' (required 
for compliance) in the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-53A1346, dated March 27, 2020, described 
previously. For information on the procedures, see this service 
information at https://www.regulations.gov by searching for and 
locating Docket No. FAA-2020-0689.

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
----------------------------------------------------------------------------------------------------------------
               Action                          Labor cost             Parts cost          Cost per product
----------------------------------------------------------------------------------------------------------------
Inspections.........................  Up to 165 work[dash]hours x               $0  Up to $1,977,525 per
                                       $85 per hour = $14,025 per                    inspection cycle.
                                       inspection cycle.
----------------------------------------------------------------------------------------------------------------


[[Page 49980]]

    The FAA estimates the following costs to do any necessary 
corrective actions that would be required based on the results of the 
proposed inspections. The FAA has no way of determining the number of 
aircraft that might need these corrective actions:

                 Estimated Costs of On-Condition Actions
------------------------------------------------------------------------
            Labor cost                Parts cost      Cost per product
------------------------------------------------------------------------
Up to 185 work-hours x $85 per                $ *   Up to $15,725.
 hour = $15,725.
------------------------------------------------------------------------
* The FAA has received no definitive data that would enable providing
  parts costs 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 has 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 that the 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 removing Airworthiness Directive (AD) 
2013-18-08, Amendment 39-17581 (78 FR 60660, October 2, 2013), and 
adding the following new AD:

The Boeing Company: Docket No. FAA-2020-0689; Product Identifier 
2020-NM-060-AD.

(a) Comments Due Date

    The FAA must receive comments on this AD action by October 1, 
2020.

(b) Affected ADs

    This AD replaces AD 2013-18-08, Amendment 39-17581 (78 FR 60660, 
October 2, 2013) (``AD 2013-18-08'').

(c) Applicability

    This AD applies to The Boeing Company Model 737-100, -200, -
200C, -300, -400, and -500 series airplanes, certificated in any 
category, as identified in Boeing Alert Service Bulletin 737-
53A1346, dated March 27, 2020.

(d) Subject

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

(e) Unsafe Condition

    This AD was prompted by reports of additional cracking in the 
horizontal and vertical chem-milled step locations outside of those 
identified in AD 2013-18-08. The FAA is issuing this AD to address 
fatigue cracking of the skin panels, which could result in sudden 
fracture and failure of the skin panels of the fuselage, and 
consequent rapid decompression of the airplane.

(f) Compliance

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

(g) Required Actions for Group 1 Through 25 Airplanes

    For airplanes identified as Group 1 through 25 in Boeing Alert 
Service Bulletin 737-53A1346, dated March 27, 2020, except as 
specified in paragraph (h) of this AD: At the applicable times 
specified in paragraph 1.E., ``Compliance,'' of Boeing Alert Service 
Bulletin 737-53A1346, dated March 27, 2020, do all applicable 
actions identified as ``RC'' (required for compliance) in, and in 
accordance with, the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-53A1346, dated March 27, 2020. Actions 
identified as terminating action in Boeing Alert Service Bulletin 
737-53A1346, dated March 27, 2020, terminate the applicable required 
actions of this AD, provided the terminating action is done in 
accordance with the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-53A1346, dated March 27, 2020.

(h) Exceptions to Service Information Specifications

    (1) Where Boeing Alert Service Bulletin 737-53A1346, dated March 
27, 2020, uses the phrase ``the original issue date of this service 
bulletin,'' this AD requires using ``the effective date of this 
AD.''
    (2) Where Boeing Alert Service Bulletin 737-53A1346, dated March 
27, 2020, 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 
(j) of this AD.

(i) Required Actions for Group 26 Airplanes

    For airplanes identified as Group 26 in Alert Service Bulletin 
737-53A1346, dated March 27, 2020: Within 120 days after the 
effective date of this AD, inspect the fuselage skin along certain 
chem-milled lines for cracks, 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: 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,

[[Page 49981]]

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.
    (4) AMOCs approved previously for AD 2013-18-08 are approved as 
AMOCs for the corresponding provisions of Boeing Alert Service 
Bulletin 737-53A1346, dated March 27, 2020, that are required by 
paragraph (g) of this AD.
    (5) For service information that contains steps that are labeled 
as Required for Compliance (RC), the provisions of paragraphs 
(j)(5)(i) and (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 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, 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 August 6, 2020.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2020-17837 Filed 8-14-20; 8:45 am]
BILLING CODE 4910-13-P


