
[Federal Register Volume 77, Number 117 (Monday, June 18, 2012)]
[Proposed Rules]
[Pages 36222-36224]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-14806]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2012-0637; Directorate Identifier 2012-NM-006-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 
certain The Boeing Company Model 737-600, -700, -700C, -800, -900, and 
-900ER series airplanes. This proposed 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 
proposed AD would require repetitive inspections for cracking of the 
inboard MLG door hinge fittings; and modification of cracked fittings, 
which would terminate the repetitive inspections. We are proposing 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; loss of the MLG door assembly could impact the flight control 
surfaces and result in reduced controllability of the airplane.

DATES: We must receive comments on this proposed AD by August 2, 2012.

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 proposed AD, contact 
Boeing Commercial Airplanes, Attention: Data & Services Management, 
P.O. Box 3707, MC 2H-65, Seattle, Washington 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, Washington. 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 proposed AD, 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: Nancy Marsh, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue SW., Renton, Washington 98057-3356; phone: 425-917-
6440; fax: 425-917-6590; email: nancy.marsh@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-2012-0637; 
Directorate Identifier 2012-NM-006-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will consider all comments received by the closing date and may amend 
this proposed AD 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 received a report of an inboard MLG door assembly departure due 
to premature fatigue cracking in the inboard MLG door hinge fittings. 
Fatigue cracking in the inboard MLG door hinge fittings could result in 
loss of the MLG door assembly from the airplane; such loss could impact 
the flight control surfaces and result in reduced controllability of 
the airplane.

[[Page 36223]]

Relevant Service Information

    We reviewed Boeing Alert Service Bulletin 737-52A1167, dated 
December 1, 2011. The service information describes procedures for 
doing repetitive detailed or surface high frequency eddy current (HFEC) 
inspections for cracking of the inboard MLG door hinge fittings; and 
modification of fittings, which would eliminate the need for the 
repetitive inspections. The modification consists of replacing the 
hinge fitting assembly. The initial compliance time is before 10,000 
total flight cycles, within 10,000 flight cycles since replacement, or 
within 600 flight cycles after the effective date of this AD, whichever 
occurs latest. The repetitive interval is 600 flight cycles or 5,500 
flight cycles depending on inspection type.

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 accomplishing the actions specified 
in the service information described previously.

Costs of Compliance

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

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

    We estimate the following costs to do any necessary replacements 
that would be required based on the results of the proposed inspection. 
We have no way of determining the number of aircraft that might need 
these replacements:

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

    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.

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):

The Boeing Company: Docket No. FAA-2012-0637; Directorate Identifier 
2012-NM-006-AD.

(a) Comments Due Date

    We must receive comments by August 2, 2012.

(b) Affected ADs

    None.

(c) Applicability

    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.

(d) Subject

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

[[Page 36224]]

(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; loss of 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 (h) of this AD, at the 
applicable time in paragraph 1.E. 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. If any cracking is 
found, before further flight, modify the inboard MLG door hinge 
fittings on both left- and right-side inboard MLG doors, in 
accordance with the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-52A1167, dated December 1, 2011. Repeat either 
inspection at the applicable time in paragraph 1.E. of Boeing Alert 
Service Bulletin 737-52A1167, dated December 1, 2011. Doing the 
modification terminates the inspection requirements of this AD.

(h) Exception

    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.

(i) 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: 9-ANM-Seattle-ACO-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 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.

(i) Related Information

    (1) 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, Washington 
98057-3356; phone: 425-917-6440; fax: 425-917-6590; email: 
nancy.marsh@faa.gov.
    (2) For service information identified in this AD, contact 
Boeing Commercial Airplanes, Attention: Data & Services Management, 
P.O. Box 3707, MC 2H-65, Seattle, Washington 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, Washington. For information on the 
availability of this material at the FAA, call 425-227-1221.

    Issued in Renton, Washington, on June 8, 2012.
Michael Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2012-14806 Filed 6-15-12; 8:45 am]
BILLING CODE 4910-13-P


