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[Federal Register Volume 79, Number 27 (Monday, February 10, 2014)]
[Proposed Rules]
[Pages 7601-7603]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2014-02715]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2014-0010; Directorate Identifier 2012-NM-218-AD]
RIN 2120-AA64

Airworthiness Directives; Learjet Inc. 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 Learjet Inc. Model 45 airplanes. This proposed AD was prompted 
by a report of two cases of premature corrosion found on the structural 
support flange for the engine thrust reverser. This proposed AD would 
require doing a fluorescent penetrant inspection of the metallic 
components of the thrust reverser's attach flange for any corrosion; 
inspecting the thrust reverser flange for damage to the sealant, as 
applicable; installing sealants and gaskets, as applicable, to the 
thrust reverser flanges and service island flanges; and related 
investigative and corrective actions as necessary. We are proposing 
this AD to prevent failure of the thrust reverser structural support, 
which could result in departure of the thrust reverser from the engine 
that could subsequently result in damage to the adjacent support 
structure and engine controls, airframe structure, and control 
surfaces. Departing thrust reversers could also result in injury to 
persons on the ground.

DATES: We must receive comments on this proposed AD by March 27, 2014.

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 
Learjet, Inc., One Learjet Way, Wichita, KS 67209-2942; telephone 316-
946-2000; fax 316-946-2220; email ac.ict@aero.bombardier.com; Internet 
http://www.bombardier.com. You may view this referenced service 
information at the FAA, Transport Airplane Directorate; 1601 Lind 
Avenue SW., Renton, WA 98057-3356. 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 by searching for and locating Docket No. FAA-2014-
0010; 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: Paul Chapman, Aerospace Engineer, 
Airframe and Services Branch, ACE-118W, FAA, Wichita Aircraft 
Certification Office, 1801 Airport Road, Room 100, Mid-Continent 
Airport, Wichita, KS 67209; phone: (316) 946-4152; fax: (316) 946-4107; 
email: paul.chapman@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-2014-0010; 
Directorate Identifier 2012-NM-218-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 two cases of premature corrosion found on 
the structural support flange for the engine thrust reverser that 
attaches the thrust reverser to the engine. The thrust reverser's 
attach flange is made of aluminum and the corrosion of that flange can 
be caused by contact with exposed graphite fibers from the engine's 
composite bypass duct. This condition, if not corrected, could result 
in failure of the thrust reverser structural support which could result 
in departure of the thrust reverser from the engine that could 
subsequently result in damage to the adjacent support structure and 
engine controls, airframe structure, and control surfaces. Departing 
thrust reversers could also result in injury to persons on the ground.

Relevant Service Information

    We reviewed Bombardier Service Bulletin 40-78-03, Revision 1, dated

[[Page 7602]]

November 5, 2012 (for Model 45 airplanes having S/N 45-2001 through 45-
2132); and Bombardier Service Bulletin 45-78-9, Revision 1, dated 
November 5, 2012 (for Model 45 airplanes having S/N 45-005 through 45-
436). Those service bulletins describe inspecting the thrust reverser's 
attach flange for damage to the sealant, as applicable, and installing 
sealants and gaskets as applicable to the thrust reverser flanges and 
service island flanges.
    We also reviewed Nordam Service Bulletin 5045 78-13, dated January 
17, 2012 (for Model 45 airplanes having S/N 45-005 through 45-420 
inclusive and S/N 45-2001 through 45-2129 inclusive), which describes 
procedures for fluorescent penetrant inspection of the metallic 
components of the thrust reverser's attach flange for any corrosion, 
and related investigative and corrective actions. Corrective actions 
include removing corrosion from the thrust reverser's attach flange, 
applying finishes, contacting the manufacturer, and replacing the 
engine attach flange. Related investigative actions include doing 
further fluorescent penetrant inspection for any remaining corrosion, 
and measuring to ensure a minimum material thickness.

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, except as discussed 
under ``Difference Between the Proposed AD and the Service 
Information.''

Difference Between Proposed AD and the Service Information

    Although Nordam Service Bulletin 5045 78-13, dated January 17, 
2012, specifies that operators may contact the manufacturer for 
disposition of certain repair conditions, this proposed AD would 
require operators to repair those conditions in accordance with a 
method approved by the FAA.

Costs of Compliance

    We estimate that this proposed AD affects 365 airplanes of U.S. 
registry.
    We estimate the following costs to comply with this proposed AD:

                                                                     Estimated Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                               Number of  U.S.          Cost on U.S.
               Action                      Labor cost              Parts cost           Cost per product           products              operators
--------------------------------------------------------------------------------------------------------------------------------------------------------
Inspections and installing sealants  Between 26 and 36 work- Between $1,216 and      Between $3,426 and     730 thrust reversers   Between $2,500,980
 and gaskets.                         hours x $85 per hour    $1,476 per thrust       $4,536 per thrust      (365 airplanes).       and $3,311,280.
                                      = Between $2,210 and    reverser.               reverser.
                                      $3,060 per thrust
                                      reverser.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    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 
this replacement.

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                Action                        Labor cost               Parts cost            Cost per product
----------------------------------------------------------------------------------------------------------------
Replacing thrust reverser attachment   40 work-hours x $85 per  $1,200 per thrust        $4,600 per thrust
 flange.                                hour = $3,400 per        reverser.                reverser.
                                        thrust reverser.
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    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:

[[Page 7603]]

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):

Learjet Inc.: Docket No. FAA-2014-0010; Directorate Identifier 2012-
NM-218-AD.

(a) Comments Due Date

    We must receive comments by March 27, 2014.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to Learjet Inc. Model 45 airplanes having serial 
numbers (S/N) 45-005 through 45-436 inclusive, and 45-2001 through 
45-2132 inclusive, certificated in any category, that are equipped 
with composite engine fan bypass ducts.

    Note 1 to paragraph (c) of this AD:  Learjet Model 45 airplanes 
having S/Ns 45-2001 and subsequent are commonly referred to as Model 
40 airplanes or Lear 40 Model 45 airplanes as a marketing 
designation.

(d) Subject

    Air Transport Association (ATA) of America Code 78, Engine 
Exhaust.

(e) Unsafe Condition

    This AD was prompted by a report of two cases of premature 
corrosion found on the structural support flange for the engine 
thrust reverser. We are issuing this AD to prevent failure of the 
thrust reverser structural support, which could result in departure 
of the thrust reverser from the engine that could subsequently 
result in damage to the adjacent support structure and engine 
controls, airframe structure, and control surfaces. Departing thrust 
reversers could also result in injury to persons on the ground.

(f) Compliance

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

(g) Inspections and Sealant Installation With Applicable Related 
Investigative and Corrective Actions

    Within 1,200 flight hours or 48 months after the effective date 
of this AD, whichever occurs first, do the requirements of paragraph 
(g)(1) of this AD; and for the airplanes identified in paragraph 
(g)(2) of this AD, do the requirements of paragraph (g)(2) of this 
AD concurrently.
    (1) Do a detailed inspection of the thrust reverser flange for 
damage to the sealant, as applicable, and install sealants and 
gaskets before further flight, as applicable, to the thrust reverser 
flanges and service island flanges, in accordance with the 
Accomplishment Instructions of Bombardier Service Bulletin 40-78-03, 
Revision 1, dated November 5, 2012 (for Model 45 airplanes having S/
N 45-2001 through 45-2132 inclusive); or Bombardier Service Bulletin 
45-78-9, Revision 1, dated November 5, 2012 (for Model 45 airplanes 
having S/N 45-005 through 45-436 inclusive).
    (2) For Model 45 airplanes having S/N 45-2001 through 45-2129 
inclusive and S/N 45-005 through 45-420 inclusive: Do a fluorescent 
penetrant inspection for corrosion of the metallic components of the 
thrust reverser's attach flange for any corrosion, and all 
applicable related investigative and corrective actions, in 
accordance with the Accomplishment Instructions of Nordam Service 
Bulletin 5045 78-13, dated January 17, 2012, except as required by 
paragraph (h) of this AD. Do all applicable related investigative 
and corrective actions before further flight.

(h) Exception to the Nordam Service Information

    If any material thickness less than the minimum allowable 
thickness is found during any inspection required by paragraph 
(g)(2) of this AD, and Nordam Service Bulletin 5045 78-13, dated 
January 17, 2012, specifies contacting Bombardier Learjet for 
appropriate action: Before further flight, repair the thrust 
reverser's attach flange in accordance with a method approved by the 
Manager, Wichita Aircraft Certification Office (ACO), FAA. For a 
repair method to be approved by the Manager, Wichita ACO, as 
required by this paragraph, the Manager's approval letter must 
specifically refer to this AD.

(i) 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 Bombardier Service Bulletin 40-78-
03, dated February 27, 2012 (for Model 45 airplanes having S/N 45-
2001 through 45-2132); or Bombardier Service Bulletin 45-78-9, dated 
February 27, 2012 (for Model 45 airplanes having S/N 45-005 through 
45-436).

(j) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Wichita 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 paragraph 
(k)(1) of this AD.
    (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.

(k) Related Information

    (1) For more information about this AD, contact Paul Chapman, 
Aerospace Engineer, Airframe and Services Branch, ACE-118W, FAA, 
Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, 
Mid-Continent Airport, Wichita, KS 67209; phone: (316) 946-4152; 
fax: (316) 946-4107; email: paul.chapman@faa.gov.
    (2) For service information identified in this AD, contact 
Learjet, Inc., One Learjet Way, Wichita, KS 67209-2942; telephone 
316-946-2000; fax 316-946-2220; email ac.ict@aero.bombardier.com; 
Internet http://www.bombardier.com. You may view this 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 January 22, 2014.
Jeffrey E. Duven,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2014-02715 Filed 2-7-14; 8:45 am]
BILLING CODE 4910-13-P
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