[Federal Register Volume 76, Number 223 (Friday, November 18, 2011)]
[Proposed Rules]
[Pages 71472-71474]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-29800]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2011-1231; Directorate Identifier 2011-NM-088-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 would require inspecting to 
detect damage to the upper fire seals on the forward edge of the thrust 
reverser, where the fire seal contacts the 12-o'clock engine strut, and 
for correct stiffness and vent holes, and doing corrective actions if 
necessary; and installing a bracket for the fire seal. This proposed AD 
was prompted by reports of damaged fire seals on the forward edge of 
the thrust reverser. We are proposing this AD to detect and correct 
damage to the fire seals, which could result in damage to the strut 
structure and the thrust reverser firewall. Such damage could 
significantly deteriorate the protection capacity of the fire 
extinguishing system and result in an uncontrolled fire.

DATES: We must receive comments on this proposed AD by January 3, 2012.

ADDRESSES: You may send comments 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: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue SE., Washington, DC 20590, 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; email 
[email protected]; 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 (telephone (800) 647-5527) is in the 
ADDRESSES section. Comments will be available in the AD docket shortly 
after receipt.

FOR FURTHER INFORMATION CONTACT: Chris R. Parker, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue SW., Renton, Washington 98057-3356; phone: 
(425) 917-6496; fax: (425) 917-6590; email: [email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2011-1231; 
Directorate Identifier 2011-NM-088-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 have received reports of damaged fire seals on the forward edge 
of the thrust reverser, where the fire seal contacts the 12-o'clock 
engine strut. The damage has been reported as light wear marks, tears, 
and holes in the bulb-part of the fire seal. The damage to the seal is 
attributed to insufficient seal stiffness and/or missing vent holes. If 
a damaged seal remained in service for an extended time, damage also 
could result to the 12-o'clock strut structure and the thrust reverser 
firewall. Such damage could significantly deteriorate the protection 
capacity of the fire extinguishing system and result in an uncontrolled 
fire.

Relevant Service Information

    We have reviewed Boeing Special Attention Service Bulletin 737-78-
1086, dated October 6, 2010. This service information describes 
procedures for a general visual inspection on the upper fire seals on 
the forward edge of the thrust reversers, where the fire seals contact 
the 12-o'clock engine strut, for damage and correct stiffness, and for 
sufficient vent holes behind the upper fire seals; and corrective 
actions if necessary. Corrective actions include replacing any damaged 
fire seal, drilling vent holes in the upper fire seal if needed. The 
service information also specifies installing a new bracket behind the 
fire seal retainer to further stiffen the seal.

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

[[Page 71473]]

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.

Costs of Compliance

    We estimate that this proposed AD will affect 968 airplanes of U.S. 
registry.
    We estimate the following costs to comply with this proposed AD:

                                                 Estimated Costs
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                                                                                     Cost per      Cost on U.S.
               Action                         Labor cost            Parts cost        product        operators
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General visual inspection and        18 work-hours x $85 per                $756          $2,286      $2,212,848
 bracket installation.                hour = $1,530.
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    We estimate the following costs to do necessary repairs and 
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 repairs.

                                               On-Condition Costs
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                                                                                                     Cost per
                   Action                                 Labor cost                Parts cost        product
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Drill vent holes (up to 8).................  1 work-hour x $85 per hour = $85...              $0             $85
Replace fire seal (up to 4)................  8 work-hours x $85 per hour = $680.           8,010           8,690
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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-2011-1231; Directorate Identifier 
2011-NM-088-AD.

Comments Due Date

    (a) We must receive comments by January 3, 2012.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to The Boeing Company Model 737-600, -700, -
700C, -800, -900, and -900ER series airplanes with line numbers 1 
through 3029 inclusive; certificated in any category.

Subject

    (d) Joint Aircraft System Component (JASC)/Air Transport 
Association (ATA) of America Code 78: Engine exhaust.

Unsafe Condition

    (e) This AD was prompted by reports of damaged upper fire seals 
on the forward edge of the thrust reversers. We are issuing this AD 
to detect and correct damage to the fire seals, which could result 
in damage to the strut structure and the thrust reverser firewall. 
Such damage could significantly deteriorate the protection capacity 
of the fire extinguishing system and result in an uncontrolled fire.

Compliance

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

Inspections and Corrective Actions

    (g) Within 36 months after the effective date of this AD: Do a 
general visual inspection of the left and right thrust reverser 
halves of each engine for damage to the upper fire seal, for 
stiffness of the upper fire seal, and for missing vent holes as 
applicable, in accordance with paragraph 3.B. of the Accomplishment 
Instructions of Boeing Special Attention Service Bulletin 737-78-
1086, dated October 6, 2010.
    (1) If, during the inspection required by paragraph (g) of this 
AD, no upper fire seal damage is found, and the fire seal has the 
correct stiffness: Before further flight, drill vent holes if they 
are missing, and install a new bracket behind the upper fire seal 
retainer, in accordance with paragraph 3.B. of

[[Page 71474]]

the Accomplishment Instructions of Boeing Special Attention Service 
Bulletin 737-78-1086, dated October 6, 2010.
    (2) If, during the inspection required by paragraph (g) of this 
AD, upper fire seal damage or insufficient fire seal stiffness is 
found: Before further flight, install a new upper fire seal, drill 
vent holes if they are missing, and install a new bracket behind the 
upper fire seal retainer, in accordance with paragraph 3.B. of the 
Accomplishment Instructions of Boeing Special Attention Service 
Bulletin 737-78-1086, dated October 6, 2010.

Alternative Methods of Compliance (AMOCs)

    (h)(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.

Related Information

    (i) For more information about this AD, contact Chris R. Parker, 
Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle ACO, 
1601 Lind Avenue SW., Renton, Washington 98057-3356; phone: (425) 
917-6496; fax: (425) 917-6590; email: [email protected].

    Issued in Renton, Washington, on November 8, 2011.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2011-29800 Filed 11-17-11; 8:45 am]
BILLING CODE 4910-13-P