[Federal Register Volume 83, Number 92 (Friday, May 11, 2018)]
[Proposed Rules]
[Pages 21948-21951]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-09978]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2018-0393; Product Identifier 2018-NM-010-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 737-600, -700, -700C, -800, -900, and -900ER 
series airplanes. This proposed AD was prompted by reports of loose, 
worn, or missing attachment bolts for the main landing gear (MLG) 
center door assemblies. This proposed AD would require repetitive 
detailed inspections of the forward and aft MLG center door assembly 
attachments for loose, missing, damaged, or bottomed out attachment 
bolts; any wear to the retention clip assemblies as applicable; and 
applicable on-condition actions. This proposed AD would also provide an 
optional terminating action for the repetitive inspections. Since this 
is a rotable parts issue, the applicability of this AD has been 
expanded beyond the airplanes listed in the related service bulletin to 
include all airplanes on which the MLG center door assemblies may be 
installed. We are proposing this AD to address the unsafe condition on 
these products.

DATES: We must receive comments on this proposed AD by June 25, 2018.

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 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-2018-0393.

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-2018-
0393; or in person at the Docket Management Facility 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

[[Page 21949]]

other information. The street address for the Docket Office (phone: 
800-647-5527) is in the ADDRESSES section. Comments will be available 
in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Alan Pohl, Aerospace Engineer, 
Airframe Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des 
Moines, WA 98198; phone and fax: 206-231-3527; email: 
[email protected].

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-2018-0393; 
Product Identifier 2018-NM-010-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 
will also post a report summarizing each substantive verbal contact we 
receive about this proposed AD.

Discussion

    We have received reports of loose, worn, or missing attachment 
bolts of the MLG center door assemblies. One operator reported the 
departure and loss of the center and inboard door assemblies from the 
left MLG during flight on a Model 737-800 series airplane. The airplane 
had accumulated 28,279 flight cycles when the incident occurred. There 
have also been several reports of the two inboard bolts that attach the 
MLG center door assembly to the shock strut cylinder being loose or 
missing. One operator reported loose, worn, and missing attachment 
bolts on several airplanes that had accumulated from 15,921 to 31,673 
flight cycles. This condition, if not corrected, could result in 
departure of the center and inboard door assemblies, subsequent damage 
to the main flap and horizontal stabilizer, and loss of control of the 
airplane.
    To support operations, many operators have put processes in place 
that, given certain conditions, allow them to rotate or transfer parts 
or equipment within their fleets to different aircraft than what is 
defined in the manufacturer's type design. We have determined that the 
parts or equipment subject to the unsafe condition addressed by this 
proposed AD may have been rotated or transferred in this manner, due to 
similarity with parts or equipment not subject to the unsafe condition 
addressed by this proposed AD. Therefore, this proposed AD includes all 
Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes.

Related Service Information Under 1 CFR Part 51

    We reviewed Boeing Special Attention Service Bulletin 737-52-1170, 
Revision 1, dated December 19, 2017 (``BSASB 737-52-1170, R1''). The 
service information describes procedures for repetitive detailed 
inspections of the forward and aft MLG center door assembly attachments 
for loose, missing, damaged, or bottomed out attachment bolts; and any 
wear to the retention clip assemblies as applicable; and applicable on-
condition actions. The service information also describes procedures 
for modification of the MLG center door assembly retention clip 
assemblies as an optional terminating action for the repetitive 
inspections. 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 BSASB 737-52-1170, R1, described previously, except as 
discussed under ``Differences Between this Proposed AD and the Service 
Information,'' and 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-2018-0393.

Differences Between This Proposed AD and the Service Information

    The effectivity of BSASB 737-52-1170, R1, is limited to Model 737-
600, -700, -700C, -800, -900, and -900ER series airplanes line numbers 
1 through 6724 inclusive and 6736. The affected MLG center door 
assemblies are rotable parts, and we have determined that these parts 
could later be installed on airplanes that were initially delivered 
with acceptable MLG center door assemblies, thereby subjecting those 
airplanes to the unsafe condition. Therefore, the applicability of this 
proposed AD includes all Model 737-600, -700, -700C, -800, -900, and -
900ER series airplanes to address the rotability of these parts. This 
difference has been coordinated with Boeing.
    Where BSASB 737-52-1170, R1, specifies Group 3 airplanes as having 
line numbers 4275 through 6724 inclusive, and 6736, this proposed AD 
specifies Group 3 airplanes as line number 4275 through any airplane 
with an original Certificate of Airworthiness or an original Export 
Certificate of Airworthiness dated ``on or before the effective date of 
this AD,'' as specified in paragraph (c)(3) of this proposed AD.
    For Model 737-600, -700, -700C, -800, -900, and -900ER series 
airplanes with an original Certificate of Airworthiness or an original 
Export Certificate of Airworthiness dated after the effective date of 
the final rule, operators would not be required to complete the actions 
described in paragraph (g) of this proposed AD, but would be required 
to comply with the parts installation prohibition in paragraph (j) of 
this proposed AD.

Costs of Compliance

    We estimate that this proposed AD affects 1,814 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
----------------------------------------------------------------------------------------------------------------
Inspection.....................  2 work-hours x $85 per               $0  $170 per            $308,380 per
                                  hour = $170 per                          inspection cycle.   inspection cycle.
                                  inspection cycle.
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[[Page 21950]]


                                 Estimated Costs for Optional Terminating Action
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                Action                            Labor cost              Parts cost        Cost per product
----------------------------------------------------------------------------------------------------------------
Modification..........................  Up to 6 work-hours x $85 per            $2,900  Up to $3,410.
                                         hour = Up to $510.
----------------------------------------------------------------------------------------------------------------

    We have received no definitive data that would enable us to provide 
cost estimates for the on-condition actions specified in this proposed 
AD.
    According to the manufacturer some of the costs of this proposed AD 
may be covered under warranty, thereby reducing the cost impact on 
affected individuals. We do not control warranty coverage for affected 
individuals. As a result, we have included all costs in our cost 
estimate.

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 to the Director of the System Oversight 
Division.

Regulatory Findings

    We 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) Is not a ``significant rule'' under the DOT Regulatory Policies 
and 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-2018-0393; Product Identifier 
2018-NM-010-AD.

(a) Comments Due Date

    We must receive comments by June 25, 2018.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to all The Boeing Company Model 737-600, -700, -
700C, -800, -900, and -900ER series airplanes, certificated in any 
category, as specified in paragraphs (c)(1) through (c)(4) of this 
AD.
    (1) Airplanes in Group 1, and in Group 2, Configuration 1, as 
identified in Boeing Special Attention Service Bulletin 737-52-1170, 
Revision 1, dated December 19, 2017 (``BSASB 737-52-1170, R1'').
    (2) Airplanes in Group 2, Configuration 2, as identified in 
BSASB 737-52-1170, R1.
    (3) Airplanes in Group 3, as identified in BSASB 737-52-1170, 
R1, except where this service bulletin specifies the groups as line 
numbers 4275 through 6724 inclusive, and 6736, this AD specifies 
those groups as line number 4275 through any line number of an 
airplane with an original Certificate of Airworthiness or an 
original Export Certificate of Airworthiness dated on or before the 
effective date of this AD.
    (4) All Model 737-600, -700, -700C, -800, -900 and -900ER series 
airplanes with an original Certificate of Airworthiness or an 
original Export Certificate of Airworthiness dated after the 
effective date of this AD.

(d) Subject

    Air Transport Association (ATA) of America Code 52, Doors.

(e) Unsafe Condition

    This AD was prompted by reports of loose, worn, or missing 
attachment bolts for the main landing gear (MLG) center door 
assemblies. We are issuing this AD to address loose, missing, 
damaged, or bottomed out attachment bolts, and any wear to the 
retention clip assemblies, which could result in departure of the 
center and inboard door assemblies, subsequent damage to the main 
flap and horizontal stabilizer, and loss of control of the airplane.

(f) Compliance

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

(g) Required Actions

    For airplanes identified in paragraphs (c)(1), (c)(2), or (c)(3) 
of this AD: Except as required by paragraph (h) of this AD, at the 
applicable time specified in Tables 1 through 6, as applicable, of 
paragraph 1.E., Compliance, of BSASB 737-52-1170, R1, do all 
applicable actions identified as ``RC'' (required for compliance) 
in, and in accordance with, the Accomplishment Instructions of BSASB 
737-52-1170, R1.

(h) Exceptions to Service Information Specifications

    For purposes of determining compliance with the requirements of 
this AD: Where BSASB 737-52-1170, Revision 1, uses the phrase ``the 
original issue date of this service bulletin,'' this AD requires 
using ``the effective date of this AD.''

(i) Optional Terminating Action for Repetitive Inspections

    Accomplishment of the modification of the MLG center door 
retention clip assemblies specified in Part 5 of the Accomplishment 
Instructions of BSASB 737-52-1170, R1, terminates the repetitive 
inspections required by paragraph (g) of this AD for that MLG center 
door retention clip only. The requirements of paragraph (j) of this 
AD continue to apply.

[[Page 21951]]

(j) Parts Installation Limitation

    As of the effective date of this AD, no person may install an 
MLG center door assembly on any airplane unless all actions for 
Group 3 airplanes identified as RC in, and in accordance with, the 
Accomplishment Instructions of BSASB 737-52-1170, R1, have been 
accomplished on that MLG center door assembly within the compliance 
times specified in Tables 4, 5, and 6, as applicable, of paragraph 
1.E., Compliance, of BSASB 737-52-1170, R1.

(k) Credit for Previous Actions

    This paragraph provides credit for the actions specified in 
paragraph (g) of this AD, if those actions were performed before the 
effective date of this AD using Boeing Special Attention Service 
Bulletin 737-52-1170, dated July 29, 2014.

(l) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Seattle 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 (m)(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 Commercial Airplanes Organization 
Designation Authorization (ODA) that has been authorized by the 
Manager, Seattle ACO Branch, 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 (h) of this AD: For service 
information that contains steps that are labeled as RC, the 
provisions of paragraphs (l)(4)(i) and (l)(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.

(m) Related Information

    (1) For more information about this AD, contact Alan Pohl, 
Aerospace Engineer, Airframe Section, FAA, Seattle ACO Branch, 2200 
South 216th St., Des Moines, WA 98198; phone and fax: 206-231-3527; 
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 in Des Moines, Washington, on April 27, 2018.
Michael Kaszycki,
Acting Director, System Oversight Division, Aircraft Certification 
Service.
[FR Doc. 2018-09978 Filed 5-10-18; 8:45 am]
 BILLING CODE 4910-13-P


