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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 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:
alan.pohl@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-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
|
Action
|
Labor cost
|
Parts cost
|
Cost per
product
|
Cost on
U.S. operators
|
| Inspection |
2 work-hours x $85 per hour =
$170 per inspection cycle |
$0 |
$170 per inspection cycle |
$308,380 per inspection cycle |
Estimated Costs for Optional Terminating
Action
|
Action
|
Labor cost
|
Parts cost
|
Cost per
product
|
| Modification |
Up to 6 work-hours x $85 per
hour = Up to $510 |
$2,900 |
Up to $3,410 |
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
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]
2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive (AD):
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