
[Federal Register Volume 84, Number 41 (Friday, March 1, 2019)]
[Proposed Rules]
[Pages 6984-6986]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-03468]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2019-0023; Product Identifier 2018-NM-145-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 all 
The Boeing Company Model 737-100, 737-200, 737-200C, 737-300, 737-400, 
and 737-500 series airplanes. This proposed AD was prompted by reports 
of cracks in the frame webs below the passenger floor. This proposed AD 
would require repetitive inspections for cracking of the fuselage lower 
lobe frames, and applicable on-condition actions. This proposed AD 
would also provide an optional terminating action for certain 
repetitive inspections. We are proposing this AD to address the unsafe 
condition on these products.

DATES: We must receive comments on this proposed AD by April 15, 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 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-2019-0023.

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-
0023; 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: Lu Lu, Aerospace Engineer, Airframe 
Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des Moines, WA 
98198; phone and fax: 206-231-3525; email: lu.lu@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-2019-0023; 
Product Identifier 2018-NM-145-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

[[Page 6985]]

will also post a report summarizing each substantive verbal contact we 
receive about this proposed AD.

Discussion

    We have received reports of cracks in frame webs below the 
passenger floor in Section 46 from Station (STA) 727A to STA 1006 
between Stringers S-17L and S-17R. The cracks have been found at the 
typical and triangular stringer cutouts, the frame inner chord common 
to the channel-cargo floor support, the failsafe chord attachments to 
the frame web, the frame integral inboard chord at the voice recorder 
support, the open tooling holes, the lower lobe frame splice, the frame 
web at stringer clips, the frame web at the water tank shear clip 
attachments, and the frame web locations hidden by stringer clips and 
intercostals on opposite sides of the frame. Additionally, there was 
one report of a frame web severed that did not occur at a fatigue 
detail.
    Cracks in frame webs, if not addressed, could result in propagation 
of cracks until the frame severs. Continued operation of the airplane 
with multiple adjacent severed frames, or the combination of a severed 
frame adjacent to fuselage skin chem-milled cracks, could result in an 
uncontrolled decompression and loss of structural integrity of the 
airplane.

Related Service Information Under 1 CFR Part 51

    We reviewed Boeing Alert Service Bulletin 737-53A1362, dated 
September 20, 2018. The service information describes procedures for 
repetitive inspections for cracking of the fuselage lower lobe frames, 
applicable on-condition actions, and an optional modification of the 
tooling holes and insulation attachment holes. On-condition actions 
include repetitive inspections for cracking of the lower lobe frames, 
repair, and repetitive post-repair inspections for cracking.
    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 as ``RC'' (required for compliance) in the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1362, dated 
September 20, 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-2019-0023.

Costs of Compliance

    We estimate that this proposed AD affects 262 airplanes of U.S. 
registry. We estimate the following costs to comply with this proposed 
AD:

                                      Estimated Costs for Required Actions
----------------------------------------------------------------------------------------------------------------
                                                                                                Cost on U.S.
            Action                   Labor cost         Parts cost      Cost per product          operators
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Inspection...................  Up to 56 work-hours x              $0  Up to $4,760 per      Up to $1,247,120 per
                                $85 per hour =                         inspection cycle.     inspection cycle.
                                $4,760 per
                                inspection cycle.
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                                      Estimated Costs for Optional Actions
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               Action                         Labor cost            Parts cost           Cost per product
----------------------------------------------------------------------------------------------------------------
Modification.......................  1 work-hour x $85 per hour              (*)  $85 per hole.
                                      = $85 per hole.
----------------------------------------------------------------------------------------------------------------
* Parts and materials (e.g., rivets, bolts, collars, primer, adhesive) are supplied by the operator.

    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 have 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) Is not a ``significant rule'' under the DOT Regulatory Policies 
and

[[Page 6986]]

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-2019-0023; Product Identifier 
2018-NM-145-AD.

(a) Comments Due Date

    The FAA must receive comments on this AD action by April 15, 
2019.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to all The Boeing Company Model 737-100, 737-
200, 737-200C, 737-300, 737-400, and 737-500 series airplanes, 
certificated in any category.

(d) Subject

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

(e) Unsafe Condition

    This AD was prompted by reports of cracks in the frame webs 
below the passenger floor. We are issuing this AD to address cracks 
that could propagate until the frame severs. Continued operation of 
the airplane with multiple adjacent severed frames, or the 
combination of a severed frame adjacent to fuselage skin chem-milled 
cracks, could result in an uncontrolled decompression and loss of 
structural integrity of the airplane.

(f) Compliance

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

(g) Required Actions for Group 1 Airplanes

    For airplanes identified as Group 1 in Boeing Alert Service 
Bulletin 737-53A1362, dated September 20, 2018 (``BASB 737-
53A1362''): Within 120 days after the effective date of this AD, 
accomplish actions to correct the unsafe condition (e.g., 
inspections and on-condition actions) using a method approved in 
accordance with the procedures specified in paragraph (k) of this 
AD.

(h) Required Actions for Group 2 Through 20 Airplanes

    For airplanes identified as Group 2 through 20 in BASB 737-
53A1362: Except as specified in paragraph (i) of this AD, at the 
applicable times specified in paragraph 1.E., ``Compliance,'' of 
BASB 737-53A1362, do all applicable actions identified as ``RC'' 
(required for compliance) in, and in accordance with, the 
Accomplishment Instructions of BASB 737-53A1362.

(i) Optional Terminating Action for Certain Repetitive Inspections

    For airplanes identified as Group 2 through 20 in BASB 737-
53A1362, accomplishment of part 13, ``Preventive Modification of the 
Frame Web Tooling Hole and Insulation Attachment Hole in the Section 
46 Lower Lobe Frame,'' in accordance with the Accomplishment 
Instructions of BASB 737-53A1362, terminates the repetitive open 
hole high frequency eddy current inspections required by paragraph 
(h) of this AD, for the modified tooling hole or insulation 
attachment hole location only.

(j) Exceptions to Service Information Specifications

    (1) For purposes of determining compliance with the requirements 
of this AD: Where BASB 737-53A1362 uses the phrase ``the original 
issue date of this service bulletin,'' this AD requires using ``the 
effective date of this AD.''
    (2) Where BASB 737-53A1362 specifies contacting Boeing for 
repair instructions or 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 (k) of this 
AD.

(k) 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 (l)(2) 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.
    (4) Except as required by paragraph (j)(2) of this AD: For 
service information that contains steps that are labeled as Required 
for Compliance (RC), the provisions of paragraphs (k)(4)(i) and 
(k)(4)(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.

(l) Related Information

    (1) For more information about this AD, contact Lu Lu, Aerospace 
Engineer, Airframe Section, FAA, Seattle ACO Branch, 2200 South 
216th St., Des Moines, WA 98198; phone and fax: 206-231-3525; email: 
lu.lu@faa.gov.
    (2) For information about AMOCs, contact George Garrido, 
Aerospace Engineer, Airframe Section, FAA, Los Angeles ACO Branch; 
3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: 562-627-
5232; fax: 562-627-5210; email: george.garrido@faa.gov.
    (3) 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 in Des Moines, Washington, on February 21, 2019.
Dionne Palermo,
Acting Director, System Oversight Division, Aircraft Certification 
Service.
[FR Doc. 2019-03468 Filed 2-28-19; 8:45 am]
 BILLING CODE 4910-13-P


