[Federal Register Volume 78, Number 159 (Friday, August 16, 2013)]
[Rules and Regulations]
[Pages 49903-49906]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2013-18090]



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  Federal Register / Vol. 78, No. 159 / Friday, August 16, 2013 / Rules 
and Regulations  

[[Page 49903]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2012-0637; Directorate Identifier 2012-NM-006-AD; 
Amendment 39-17532; AD 2013-15-16]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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

SUMMARY: We are adopting a new airworthiness directive (AD) for certain 
The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER 
series airplanes. This AD was prompted by a report of an inboard main 
landing gear (MLG) door assembly departure due to premature fatigue 
cracking in the inboard MLG door hinge fittings. This AD requires 
repetitive inspections for cracking of the inboard MLG door hinge 
fittings; and replacement or modification of cracked fittings. This AD 
also provides an option to remove the affected MLG door. We are issuing 
this AD to detect and correct fatigue cracking in the inboard MLG door 
hinge fittings, which could result in loss of the MLG door assembly 
from the airplane, and the MLG door assembly could impact the flight 
control surfaces and result in reduced controllability of the airplane.

DATES: This AD is effective September 20, 2013.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in the AD as of September 20, 
2013.

ADDRESSES: For service information identified in this AD, contact 
Boeing Commercial Airplanes, Attention: Data & Services Management, 
P.O. Box 3707, MC 2H-65, Seattle, WA 98124-2207; telephone 206-544-
5000, extension 1; fax 206-766-5680; Internet https://www.myboeingfleet.com. You may review copies of the referenced service 
information at the FAA, Transport Airplane Directorate, 1601 Lind 
Avenue SW., Renton, WA. For information on the availability of this 
material at the FAA, call 425-227-1221.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov; 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 AD, the regulatory evaluation, 
any comments received, and other information. The address for the 
Docket Office (phone: 800-647-5527) is Document Management Facility, 
U.S. Department of Transportation, Docket Operations, M-30, West 
Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE., 
Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Nancy Marsh, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue SW., Renton, WA 98057-3356; phone: 425-917-6440; fax: 
425-917-6590; email: [email protected].

SUPPLEMENTARY INFORMATION:

Discussion

    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 
part 39 to include an AD that would apply to the specified products. 
The NPRM published in the Federal Register on June 18, 2012 (77 FR 
36222). The NPRM proposed to require repetitive inspections for 
cracking of the inboard MLG door hinge fittings; and modification of 
cracked fittings, which would terminate the repetitive inspections.

Comments

    We gave the public the opportunity to participate in developing 
this AD. The following presents the comments received on the proposal 
(77 FR 36222, June 18, 2012) and the FAA's response to each comment.

Request To Extend Compliance Time

    American Airlines requested that we revise the NPRM (77 FR 36222, 
June 18, 2012) to extend the compliance time for the initial 
inspections from 10,000 total flight cycles to before 18,000 total 
flight cycles. American Airlines stated that the FAA has not provided 
sufficient evidence to warrant issuance of regulatory action with such 
a reduced compliance time. American Airlines calculated that the event 
described in the service information represents only 0.085 percent of 
the airplanes under U.S. registry, and that the event described 
occurred at 24,000 total flight cycles.
    We disagree with the request to extend the compliance time. In 
developing an appropriate compliance time for this action, we 
considered the safety implications, parts availability, and normal 
maintenance schedules for the timely accomplishment of the inspections 
and modifications. There is additional data related to the MLG door 
hinge failures that is not included in the manufacturer's service 
bulletin. Up to 10 percent of hinges inspected to date have been found 
with cracking. The cracking occurred between 11,000 and 24,000 total 
flight cycles, and has been found on both hinges of the inboard MLG 
door. In consideration of these items, we have determined that a 
compliance time of before 10,000 total flight cycles will ensure an 
acceptable level of safety and allow the inspections and modifications 
to be done during scheduled maintenance intervals for most affected 
operators. We have not changed the AD in this regard.

Request To Allow New Hinges Having Part Numbers (P/Ns) 113A8341-1 and 
113A8341-2

    American Airlines requested that we revise paragraph (g) of the 
NPRM (77 FR 36222, June 18, 2012) to allow installation of new hinges 
having P/Ns 113A8341-1 and 113A8341-2 as replacements for cracked 
hinges found during the inspections. American Airlines stated that 
paragraph 1.E., ``Compliance,'' of Boeing Alert Service Bulletin 737-
52A1167, dated December 1, 2011 (referred to in the NPRM as the 
appropriate source of service information), implies that an operator 
may install a new set of hinges having P/Ns 113A8341-1 and 113A8341-2 
and restart the inspection threshold and

[[Page 49904]]

interval; however, the Accomplishment Instructions recommend 
installation of new hinges having P/Ns 113A8341-9 and 113A8341-10 if 
cracking is found. American Airlines stated that installation of a new 
set of hinges having P/Ns 113A8341-1 and 113A8341-2 should be 
acceptable as long as the on-going repetitive inspections are 
accomplished as defined in paragraph 1.E., ``Compliance,'' of Boeing 
Alert Service Bulletin 737-52A1167, dated December 1, 2011.
    We agree to allow replacement of cracked hinges with new hinges 
having P/Ns 113A8341-1 and 113A8341-2, as long as inspections of the 
replacement hinges are accomplished at the time specified in paragraph 
1.E., ``Compliance,'' of Boeing Alert Service Bulletin 737-52A1167, 
dated December 1, 2011. We have added new paragraph (h)(2) to this AD 
to clarify that installing new MLG door hinge fittings having P/N 
113A8341-1 and 113A8341-2, is acceptable for compliance with the 
modification specified in paragraphs (g)(1)(ii) and (g)(2)(i) of this 
AD. Paragraph (h)(2) also specifies that installation of the MLG door 
hinge fittings having P/N 113A8341-1 and 113A8341-2, must be done using 
a method approved in accordance with the procedures specified in 
paragraph (j) of this AD. We have revised subsequent paragraph 
identifiers accordingly. This difference has been coordinated with 
Boeing.

Request for Clarification of Follow-On Actions

    Boeing requested that we reword paragraph (g) of the NPRM (77 FR 
36222, June 18, 2012) to clarify the follow-on actions required after 
the inspections. Boeing stated that the requirement to continue 
repetitive inspections needs to be clarified since it only pertains if 
the hinges were found to be uncracked.
    We agree that clarification is needed. The repetitive inspections 
are not required if the modification has been accomplished with hinges 
having P/Ns 113A8341-9 and 113A8341-10. However, the repetitive 
inspections are required if hinges having P/N 113A8341-1 and 113A8341-2 
are installed. We have added this clarification in paragraphs (g)(1) 
and (g)(2) of this AD.

Request To Require Modification of Only Doors Having Cracked Hinges

    Southwest Airlines (Southwest) requested that replacement of the 
hinges be required only on the door where cracks were found, rather 
than replacing both doors if cracking is found only on one door. 
Southwest stated it wants the option to not modify a door on which the 
hinges are not cracked, even though there is hinge cracking on the door 
on the other side of the airplane. Southwest added that, for a door 
that has no cracked hinges, the repetitive inspections would remain 
effective, and modification would not be required prior to further 
flight.
    We agree that only doors with cracked hinges need to be modified, 
and that the repetitive inspections specified in the AD remain in 
effect for the door that has not been modified. We have revised 
paragraph (g)(2)(i) of this AD to clarify that modification is only 
required on affected doors.

Request for the Option To Remove Inboard MLG Door in Accordance With 
the Configuration Deviation List (CDL)

    Southwest requested that we allow the option of removing the 
inboard MLG door from the airplane as specified in the CDL. Southwest 
noted that the CDL allows for continued operation without the inboard 
MLG door.
    We agree with adding an option to the AD to remove the affected 
inboard MLG door. However, the removal must be done in accordance with 
a method approved by the FAA because applicable flight effects and 
restrictions must be accounted for. In addition, if a door with new 
hinge fittings is reinstalled, the inspection required by paragraph (h) 
of this AD must be done. We have added paragraph (g)(2)(ii) of this AD 
accordingly. We have also added note 1 to paragraph (g)(2)(ii) of this 
AD to this AD to refer to the CDL as guidance.

Supplemental Type Certificate (STC) Winglet Comment

    Aviation Partners Boeing stated that the installation of winglets 
per STC ST00830SE (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgstc.nsf/0/408E012E008616A7862578880060456C?OpenDocument&Highlight=st00830se) does 
not affect the accomplishment of the manufacturer's service 
instructions.
    We have added paragraph (c)(1) to this AD to state that 
installation of STC ST00830SE (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgstc.nsf/0/408E012E008616A7862578880060456C?OpenDocument&Highlight=st00830se) does 
not affect the ability to accomplish the actions required by this AD. 
Therefore, for airplanes on which STC ST00830SE is installed, a 
``change in product'' alternative method of compliance (AMOC) approval 
request is not necessary to comply with the requirements of 14 CFR 
39.17. For all other AMOC requests, the operator must request approval 
of an AMOC in accordance with the procedures specified in paragraph (j) 
of this AD.

New Optional Installation Paragraph

    We have added new paragraph (h)(1) to this AD to clarify that 
installing new MLG door hinge fittings having P/N 113A8341-9 and 
113A8341-10, terminates the inspection requirements of this AD for only 
the door on which new fittings are installed.

Conclusion

    We reviewed the relevant data, considered the comments received, 
and determined that air safety and the public interest require adopting 
this AD with the changes described previously and minor editorial 
changes. We have determined that these minor changes:
     Are consistent with the intent that was proposed in the 
NPRM (77 FR 36222, June 18, 2012) for correcting the unsafe condition; 
and
     Do not add any additional burden upon the public than was 
already proposed in the NPRM (77 FR 36222, June 18, 2012).
    We also determined that these changes will not increase the 
economic burden on any operator or increase the scope of this AD.

Costs of Compliance

    We estimate that this AD affects 1,175 airplanes of U.S. registry.
    We estimate the following costs to comply with this AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                 Cost on U.S.
             Action                      Labor cost         Parts cost   Cost per  product        operators
----------------------------------------------------------------------------------------------------------------
Inspection......................  3 work-hours x $85 per           $0   $255 per inspection  $299,625 per
                                   hour = $255 per                       cycle.               inspection cycle.
                                   inspection cycle.
----------------------------------------------------------------------------------------------------------------


[[Page 49905]]

    We estimate the following costs to do any necessary modification 
that would be required based on the results of the inspection. We have 
no way of determining the number of airplanes that might need this 
modification:

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                 Action                             Labor cost            Parts cost       Cost per product
----------------------------------------------------------------------------------------------------------------
Modification...........................  9 work-hours x $85 per hour =       $6,550   $7,315
                                          $765.
----------------------------------------------------------------------------------------------------------------

    According to the manufacturer, some of the costs of this 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.

Regulatory Findings

    This AD will not have federalism implications under Executive Order 
13132. This AD will 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 this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Is not a ``significant rule'' under 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.

Adoption of the Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA amends 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):

2013-15-16 The Boeing Company: Amendment 39-17532; Docket No. FAA-
2012-0637; Directorate Identifier 2012-NM-006-AD.

(a) Effective Date

    This AD is effective September 20, 2013.

(b) Affected ADs

    None.

(c) Applicability

    (1) This AD applies to The Boeing Company Model 737-600, -700, -
700C, -800, -900, and -900ER series airplanes, certificated in any 
category, as identified in Boeing Alert Service Bulletin 737-
52A1167, dated December 1, 2011.
    (2) Installation of Supplemental Type Certificate (STC) 
ST00830SE (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgstc.nsf/0/408E012E008616A7862578880060456C?OpenDocument&Highlight=st00830se) 
does not affect the ability to accomplish the actions required by 
this AD. Therefore, for airplanes on which STC ST00830SE is 
installed, a ``change in product'' alternative method of compliance 
(AMOC) approval request is not necessary to comply with the 
requirements of 14 CFR 39.17.

(d) Subject

    Joint Aircraft System Component (JASC)/Air Transport Association 
(ATA) of America Code 52, Doors.

(e) Unsafe Condition

    This AD was prompted by a report of an inboard main landing gear 
(MLG) door assembly departure due to premature fatigue cracking in 
the inboard MLG door hinge fittings. We are issuing this AD to 
detect and correct fatigue cracking in the inboard MLG door hinge 
fittings, which could result in loss of the MLG door assembly from 
the airplane, and the MLG door assembly could impact the flight 
control surfaces and result in reduced controllability of the 
airplane.

(f) Compliance

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

(g) Initial and Repetitive Inspections

    Except as provided by paragraph (i) of this AD, at the 
applicable time specified in paragraph 1.E., ``Compliance,'' of 
Boeing Alert Service Bulletin 737-52A1167, dated December 1, 2011, 
do either a detailed or surface high frequency eddy current (HFEC) 
inspection for cracking of the left- and right-side inboard MLG door 
hinge fittings, in accordance with the Accomplishment Instructions 
of Boeing Alert Service Bulletin 737-52A1167, dated December 1, 
2011.
    (1) If no cracking is found, at the times specified in paragraph 
1.E., ``Compliance,'' of Boeing Alert Service Bulletin 737-52A1167, 
dated December 1, 2011, do the actions specified in either paragraph 
(g)(1)(i) or (g)(1)(ii) of this AD, in accordance with the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
52A1167, dated December 1, 2011.
    (i) Repeat either a detailed or a surface HFEC inspection for 
cracking of the left- and right-side inboard MLG door hinge 
fittings.
    (ii) Modify the hinge fittings on the inboard MLG doors by 
installing P/N 113A8341-9 and 113A8341-10, in accordance with Part 3 
of the Accomplishment Instructions of Boeing Alert Service Bulletin 
737-52A1167, dated December 1, 2011. Doing the modification 
specified in this paragraph terminates the inspection requirements 
for only the door on which new fittings are installed.
    (2) If any cracking is found, before further flight, do the 
actions specified in either paragraph (g)(2)(i) or (g)(2)(ii) of 
this AD.
    (i) Modify the hinge fittings on all affected inboard MLG doors 
by installing P/N 113A8341-9 and 113A8341-10, in accordance with 
Part 3 of the Accomplishment Instructions of Boeing Alert Service 
Bulletin 737-52A1167, dated December 1, 2011. Doing the modification 
specified in this paragraph terminates the inspection requirements 
for only the door on which new fittings are installed.
    (ii) Remove the affected MLG door, using a method approved in 
accordance with the procedures specified in paragraph (j) of this 
AD. For airplanes on which this door is reinstalled, before further 
flight, accomplish the actions specified in either paragraph

[[Page 49906]]

(h)(1) or (h)(2) of this AD on the reinstalled door.

    Note 1 to paragraph (g)(2)(ii) of this AD: Guidance for removing 
the door can be found in Section 32-10 of Appendix CDL, 
Configuration Deviation List, Model 737-100/200/300/400/500/600/700/
800/900/900 ER Series, to the Boeing 737-700 Airplane Flight Manual 
Document D631A001.

(h) Optional Installation

    (1) Installing new MLG door hinge fittings having P/N 113A8341-9 
and 113A8341-10, terminates the inspection requirements of this AD 
for only the doors on which new fittings are installed.
    (2) Installing new MLG door hinge fittings having P/N 113A8341-1 
and 113A8341-2, is acceptable for compliance with the modification 
specified in paragraphs (g)(1)(ii) and (g)(2)(i) of this AD, 
provided the inspections (both the initial and the repetitive 
inspections) required by paragraph (g) of this AD are done within 
the applicable times specified in paragraph 1.E., ``Compliance,'' of 
Boeing Alert Service Bulletin 737-52A1167, dated December 1, 2011. 
Installation of the MLG door hinge fittings having P/N 113A8341-1 
and 113A8341-2, as applicable, must be done using a method approved 
in accordance with the procedures specified in paragraph (j) of this 
AD. Accomplishing the requirements of this paragraph does not 
terminate the inspection requirements of paragraph (g) of this AD.

(i) Exception to the Service Information

    Where Boeing Alert Service Bulletin 737-52A1167, dated December 
1, 2011, specifies a compliance time ``after the original issue date 
of this service bulletin,'' this AD requires compliance within the 
specified compliance time after the effective date of this AD.

(j) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Seattle Aircraft Certification Office (ACO), 
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 ACO, send it to the 
attention of the person identified in the Related Information 
section 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 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 to make 
those findings. For a repair method to be approved, the repair must 
meet the certification basis of the airplane, and the approval must 
specifically refer to this AD.

(k) Related Information

    For more information about this AD, contact Nancy Marsh, 
Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue SW., Renton, WA 98057-3356; 
phone: 425-917-6440; fax: 425-917-6590; email: [email protected].

(l) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference (IBR) of the service information listed 
in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this service information as applicable to do 
the actions required by this AD, unless the AD specifies otherwise.
    (i) Boeing Alert Service Bulletin 737-52A1167, dated December 1, 
2011.
    (ii) Reserved.
    (3) For service information identified in this AD, contact 
Boeing Commercial Airplanes, Attention: Data & Services Management, 
P.O. Box 3707, MC 2H-65, Seattle, WA 98124-2207; telephone 206-544-
5000, extension 1; fax 206-766-5680; Internet https://www.myboeingfleet.com.
    (4) You may view this service information at FAA, Transport 
Airplane Directorate, 1601 Lind Avenue SW., Renton, WA. For 
information on the availability of this material at the FAA, call 
425-227-1221.
    (5) You may view this service information that is incorporated 
by reference at the National Archives and Records Administration 
(NARA). For information on the availability of this material at 
NARA, call 202-741-6030, or go to: http://www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued in Renton, Washington, on July 21, 2013.
Stephen P. Boyd,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2013-18090 Filed 8-15-13; 8:45 am]
BILLING CODE 4910-13-P