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[Federal Register: August 23, 2010 (Volume 75, Number 162)]
[Proposed Rules]               
[Page 51701-51705]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr23au10-22]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2010-0802; Directorate Identifier 2009-NM-256-AD]
RIN 2120-AA64

 
Airworthiness Directives; Learjet Inc. Model 45 Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to supersede an existing airworthiness 
directive (AD) that applies to certain Learjet Inc. Model 45 airplanes. 
The existing AD currently requires, for certain airplanes, repetitive 
inspections for chafing and other damage of the case drain tube from 
the hydraulic pump case installed on the left-hand engine, and 
corrective action if necessary. The existing AD also requires, for all 
airplanes, repetitive inspections for discrepancies of the left 
engine's nacelle tubing, repetitive inspections for evidence of fluid 
leakage within the left engine accessory compartment, and corrective 
actions if necessary. This proposed AD would require replacing the left 
engine fuel and hydraulic tubing and installing a tubing support 
channel, which would terminate the repetitive inspections required in 
the existing AD. This proposed AD also removes airplanes from the 
applicability. This proposed AD results from reports of chafed 
hydraulic tubes in the left-hand engine. We are proposing this AD to 
detect and correct chafed hydraulic tubes in the left-hand engine and 
consequent hydraulic tube failure and uncontrolled loss of flammable 
fluid within the engine cowling, which could result in a fire in the 
engine nacelle and loss of control of the airplane.

DATES: We must receive comments on this proposed AD by October 7, 2010.

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 
Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-2942; telephone: 
316-946-2000; fax: 316-946-2220; e-mail: ac.ict@aero.bombardier.com; 
Internet: http://www.bombardier.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: James Galstad, Aerospace Engineer, 
Systems and Propulsion Branch, ACE-116W, FAA, Wichita Aircraft 
Certification Office, 1801 Airport Road, Room 100, Mid-Continent 
Airport, Wichita, Kansas 67209; telephone (316) 946-4135; fax (316) 
946-4107.

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-2010-0802; 
Directorate Identifier 2009-NM-256-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.

[[Page 51702]]

Discussion

    On May 20, 2009, we issued AD 2009-11-13, amendment 39-15923 (74 FR 
26288, June 2, 2009), for certain Learjet Inc. Model 45 airplanes. That 
AD requires, for certain airplanes, repetitive inspections for chafing 
and other damage of the case drain tube from the hydraulic pump case 
installed on the left-hand engine, and corrective action if necessary. 
This AD also requires, for all airplanes, repetitive inspections for 
discrepancies of the left engine's nacelle tubing, repetitive 
inspections for evidence of fluid leakage within the left engine 
accessory compartment, and corrective actions if necessary. That AD 
resulted from reports of chafed hydraulic tubes in the left-hand 
engine. We issued that AD to detect and correct chafed hydraulic tubes 
in the left-hand engine and consequent hydraulic tube failure and 
uncontrolled loss of flammable fluid within the engine cowling, which 
could result in a fire in the engine nacelle and loss of control of the 
airplane.

Actions Since Existing AD Was Issued

    The preamble to AD 2009-11-13 specifies that we consider the 
requirements ``interim action'' and that the manufacturer is developing 
a modification to address the unsafe condition. That AD explains that 
we might consider further rulemaking if a modification is developed, 
approved, and available. The manufacturer now has developed such a 
modification, and we have determined that further rulemaking is indeed 
necessary; this proposed AD follows from that determination.

Changes to the Applicability

    The applicability of AD 2009-11-13 includes airplanes having serial 
numbers (S/N) 45-002 through 45-4000 inclusive. This proposed AD would 
apply to airplanes having S/Ns 45-005 through 45-405 inclusive, and 45-
2001 through 45-2126 inclusive. Airplanes having S/Ns 45-406 through 
45-2000 and 45-2127 through 45-4000, have incorporated a design change 
in production that addresses the identified unsafe condition, and 
therefore we removed these airplanes from the applicability. We also 
removed S/N 45-002 because it is an experimental airplane at Learjet, 
and we removed S/Ns 45-003 and 45-004 because they no longer exist.

Relevant Service Information

    We have reviewed Bombardier Service Bulletins 40-71-04 (Model 45, 
serial numbers 45-2001 through 45-2126) and 45-71-7 (Model 45, serial 
numbers 45-005 through 45-405), both dated December 7, 2009. These 
service bulletins describe procedures for replacing the left engine 
fuel and hydraulic tubing and installing a tubing support channel, 
including doing a general visual inspection for galling of the fuel 
supply manifold assembly, a general visual inspection for minimum 
clearance between the firewall fuel supply tube assembly and the engine 
firewall cutout, a general visual inspection for minimum clearance 
between the lower nacelle hydraulic tube and hose assemblies, a general 
visual inspection for minimum clearance between the lower nacelle fuel 
tubes and flexible hoses, and corrective actions if necessary. The 
corrective actions include replacing the fuel supply manifold, trimming 
the cutout to meet minimum clearance specifications, and adjusting 
parts to meet minimum clearance specifications. Modification of the 
applicable in-service airplanes eliminates the need for the existing 
requirements of AD 2009-11-13.
    Bombardier Service Bulletin 45-71-7, dated December 7, 2009, 
specifies prior or concurrent accomplishment of Bombardier Service 
Bulletin 45-71-5, dated February 13, 2007, for airplanes having serial 
numbers 45-005 through 45-319, and 45-321. Bombardier Service Bulletin 
40-71-04, dated December 7, 2009, specifies prior or concurrent 
accomplishment of Bombardier Service Bulletin 40-71-02, dated February 
13, 2007, for airplanes having serial numbers 45-2001 through 45-2069. 
Bombardier Service Bulletins 45-71-5 and 40-71-02, both dated February 
13, 2007, describe the following procedures:
     For certain airplanes, changing the routing and clamping 
configuration of the engine and alternator wire harnesses, and the 
starter/generator wire bundles.
     For certain airplanes, doing a detailed inspection for 
chafing of specific hydraulic tubes located within the left engine 
nacelle between the adjacent fuel tubes and to determine if there is 
interference between the fuel tubing and hydraulic tubing, securing the 
hydraulic tubes with additional clamps, inspecting adjacent fuel tubing 
for interference with the hydraulic tubing, and corrective actions if 
necessary. Corrective actions include replacing chafed hydraulic tubes 
and replacing fuel tubes if interference is found.
     For certain airplanes, replacing the left engine hydraulic 
pump case drain tube.
     For certain airplanes, inspecting for clearance between 
the left engine hydraulic tubing with adjacent tubing, structure, and 
other components; and replacing tubing if necessary.
     For all airplanes, inspecting for clearance between the 
wire harnesses and the hydraulic and fuel tubing on the left engines, 
if necessary; and replacing tubing if necessary.
     For certain airplanes, inspecting for clearance between 
the wire harnesses and the hydraulic and fuel tubing on the right 
engines, if necessary; and replacing tubing if necessary.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to develop on other airplanes of the 
same type design. For this reason, we are proposing this AD, which 
would supersede AD 2009-11-13 and would retain the requirements of the 
existing AD until the modification is done. This proposed AD would also 
require accomplishing the actions specified in Bombardier Service 
Bulletins 40-71-04 and 45-71-7, both dated December 7, 2009; and 
Bombardier Service Bulletins 40-71-02 and 45-71-5, both dated February 
13, 2007.

Costs of Compliance

    There are about 530 airplanes of the affected design in the 
worldwide fleet. The following table provides the estimated costs for 
U.S. operators to comply with this proposed AD.

[[Page 51703]]

                                                                     Estimated Costs
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                                                                                                                     Number  of
                                                      Average                                                          U.S.-
                Action                 Work  hours   labor rate            Parts              Cost per  airplane     registered         Fleet cost
                                                      per hour                                                       airplanes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Inspection (required by AD 2009-11-              3          $85  $0......................  $255 per inspection....          325  $82,875 per inspection.
 13).
Modification (new proposed action)...           20           85  Up to $14,740...........  Up to $16,440..........          358  Up to $5,885,520.
Concurrent Action....................            4           85  $189....................  $529...................          358  $189,382.
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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 have 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 that the 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); and
    3. 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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this proposed AD and placed it in the AD docket. See the 
ADDRESSES section for a location to examine the regulatory evaluation.

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 removing amendment 39-15923 (74 FR 
26288, June 2, 2009) and adding the following new AD:

Learjet Inc.: Docket No. FAA-2010-0802; Directorate Identifier 2009-
NM-256-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by October 
7, 2010.

Affected ADs

    (b) This AD supersedes AD 2009-11-13, Amendment 39-15923.

Applicability

    (c) This AD applies to Learjet Inc. Model 45 airplanes; 
certificated in any category; serial numbers 45-005 through 45-405 
inclusive, and 45-2001 through 45-2126 inclusive.

Subject

    (d) Air Transport Association (ATA) of America Code 71: 
Powerplant.

Unsafe Condition

    (e) This AD results from reports of chafed hydraulic tubes in 
the left-hand engine. The Federal Aviation Administration is issuing 
this AD to detect and correct chafed hydraulic tubes in the left-
hand engine and consequent hydraulic tube failure and uncontrolled 
loss of flammable fluid within the engine cowling, which could 
result in a fire in the engine nacelle and loss of control of the 
airplane.

Compliance

    (f) You are responsible for having the actions required by this 
AD performed within the compliance times specified, unless the 
actions have already been done.

Restatement of Requirements of AD 2009-11-13, With No Changes

Repetitive Inspections: Case Drain Tube

    (g) For airplanes having serial numbers identified in Table 1 of 
this AD: Within 50 flight hours after June 17, 2009 (the effective 
date of AD 2009-11-13), do a detailed inspection for chafing and 
other damage of the case drain tube from the hydraulic pump case 
installed on the left-hand engine, in accordance with the applicable 
service bulletin identified in Table 1 of this AD. If any damage is 
found, before further flight, reposition or replace the tube, as 
applicable, in accordance with the Accomplishment Instructions of 
the applicable service bulletin identified in Table 1 of this AD. 
Repeat the inspection thereafter at intervals not to exceed 150 
flight hours until the modification required by paragraph (l) of 
this AD is done.

               Table 1--Service Bulletins for Inspections
------------------------------------------------------------------------
                 For--                                Use--
------------------------------------------------------------------------
Serial numbers 45-005 through 45-313     Bombardier Alert Service
 inclusive (commonly referred to as       Bulletin A45-29-15, dated
 ``M45'' airplanes).                      December 26, 2006.
Serial numbers 45-2001 through 45-2063   Bombardier Alert Service
 inclusive (commonly referred to as       Bulletin A40-29-03, dated
 ``M40'' airplanes).                      December 26, 2006.
------------------------------------------------------------------------

[[Page 51704]]

    Note 1: For the purposes of this AD, a detailed inspection is: 
``An intensive examination of a specific item, installation, or 
assembly to detect damage, failure, or irregularity. Available 
lighting is normally supplemented with a direct source of good 
lighting at an intensity deemed appropriate. Inspection aids such as 
mirror, magnifying lenses, etc., may be necessary. Surface cleaning 
and elaborate procedures may be required.''

Repetitive Inspections: Nacelle Tubing

    (h) Within 50 flight hours after June 17, 2009, do a detailed 
inspection for discrepancies of the left engine's nacelle tubing, in 
accordance with the applicable temporary revision (TR) identified in 
Table 2 of this AD. Discrepancies include damaged tubing, and 
inadequate clearance between any unsupported section of the tube or 
other tubing and surrounding components. If any discrepancy is 
found, before further flight, adjust the tubing and clamping or 
replace the tubing, as applicable, in accordance with the applicable 
TR identified in Table 2 of this AD. Repeat the inspection 
thereafter at intervals not to exceed 150 flight hours until the 
modification required by paragraph (l) of this AD is done.

                      Table 2--TRs for Inspections
------------------------------------------------------------------------
                 For--                                Use--
------------------------------------------------------------------------
Serial numbers 45-2001 through 45-4000   Learjet 40 TR 71-1, dated April
 inclusive (commonly referred to as       28, 2009, to the Learjet 40
 ``M40'' airplanes).                      Maintenance Manual MM-105.
Serial numbers 45-002 through 45-2000    Learjet 45 TR 71-1, dated April
 inclusive (commonly referred to as       28, 2009, to the Learjet 45
 ``M45'' airplanes).                      Maintenance Manual MM-104.
------------------------------------------------------------------------

Concurrent Inspections: Fluid Leakage

    (i) Concurrently with each inspection required by paragraph (h) 
of this AD, do a detailed inspection for evidence of engine oil, 
hydraulic fluid, or fuel leakage within the left engine accessory 
compartment, in accordance with the applicable maintenance manual 
section identified in Table 3 of this AD. If there is evidence of 
leakage: Before further flight, remove each plumbing clamp within 
the inspection areas specified in paragraphs (g) and (h) of this AD, 
and clean and remove all evidence of fluid leakage.

          Table 3--Maintenance Manual Sections for Inspections
------------------------------------------------------------------------
                 For--                                Use--
------------------------------------------------------------------------
Serial numbers 45-002 through 45-2000    Section 71-00-00, ``Powerplant--
 inclusive (commonly referred to as       Maintenance Practices,'' and
 ``M45'' airplanes).                      Section 71-00-01, ``Engine--
                                          Maintenance Practices,'' of
                                          the Learjet 45 Maintenance
                                          Manual MM-104, Revision 47,
                                          dated March 30, 2009.
Serial numbers 45-2001 through 45-4000   Section 71-00-01, ``Engine--
 inclusive (commonly referred to as       Maintenance Practices,'' of
 ``M40'' airplanes).                      the Learjet 40 Maintenance
                                          Manual MM-105, Revision 15,
                                          dated March 30, 2009.
------------------------------------------------------------------------

Additional Corrective Action for Fluid Leakage and Inadequate Clearance

    (j) If evidence of fluid leakage was found during any inspection 
required by paragraph (i) of this AD, or if inadequate clearance was 
found during any action required by paragraph (g) or (h) of this AD: 
Before further flight, replace each clamp associated with the fluid 
leakage or inadequate clearance with a new clamp, in accordance with 
the applicable maintenance manual identified in Table 3 of this AD.

Parts Installation

    (k) As of June 17, 2009, no person may re-install, on any 
airplane, any plumbing clamp that has been removed in accordance 
with the requirements of paragraphs (g), (h), (i), or (j) of this 
AD.

New Requirements of This AD

Terminating Action

    (l) Within 300 flight hours or 12 months after the effective 
date of this AD, whichever occurs first, do the actions specified in 
paragraphs (l)(1) and (l)(2) of this AD, in accordance with the 
Accomplishment Instructions of Bombardier Service Bulletin 40-71-04 
(Model 45, serial numbers 45-2001 through 45-2126) or 45-71-7 (Model 
45, serial numbers 45-005 through 45-405), both dated December 7, 
2009, as applicable. Accomplishment of the requirements of 
paragraphs (l) and (m), as applicable, of this AD terminates the 
requirements of paragraphs (g), (h), (i), and (j) of this AD.
    (1) Replace the left engine fuel and hydraulic tubing and 
install a tubing support channel using new parts.
    (2) Do the inspections specified in paragraphs (l)(2)(i), 
(l)(2)(ii), (l)(2)(iii), and (l)(2)(iv) of this AD and all 
applicable corrective actions. Do all applicable corrective actions 
before further flight.
    (i) A general visual inspection for galling of the fuel supply 
manifold assembly;
    (ii) A general visual inspection for minimum clearance between 
the firewall fuel supply tube assembly and the engine firewall 
cutout;
    (iii) A general visual inspection for minimum clearance between 
the lower nacelle hydraulic tube and hose assemblies; and
    (iv) A general visual inspection for minimum clearance between 
the lower nacelle fuel tubes and flexible hoses.
    (m) For airplanes having serial numbers 45-005 through 45-319, 
and 45-321, as identified in Bombardier Service Bulletin 45-71-5, 
dated February 13, 2007; and for airplanes having serial numbers 45-
2001 through 45-2069, as identified in Bombardier Service Bulletin 
40-71-02, dated February 13, 2007: Before or concurrently with 
accomplishing the requirements of paragraph (l) of this AD, do the 
applicable actions specified in paragraphs (m)(1), (m)(2), (m)(3), 
(m)(4), and (m)(5) of this AD, depending on airplane serial number 
and configuration, as specified in, and in accordance with, the 
Accomplishment Instructions of Bombardier Service Bulletin 45-71-5 
(Model 45, serial numbers 45-005 through 45-319, and 45-321), dated 
February 13, 2007; and Bombardier Service Bulletin 40-71-02 (Model 
45, serial numbers 45-2001 through 45-2069), dated February 13, 
2007; as applicable. Do all applicable corrective actions before 
further flight. If, during any inspection required by paragraph 
(m)(3), (m)(4), or (m)(5) of this AD, it is determined that 
clearances are not met, before further flight, replace the tubing in 
accordance with the Accomplishment Instructions of Bombardier 
Service Bulletin 45-71-5, dated February 13, 2007; and Bombardier 
Service Bulletin 40-71-02, dated February 13, 2007; as applicable.
    (1) Change the routing and clamping configuration of the engine 
and alternator wire harnesses and the starter/generator wire 
bundles.
    (2) Do a detailed inspection for chafing damage of specific 
hydraulic tubes located within the left engine nacelle between the 
adjacent fuel tubes and to determine if there is interference 
between the fuel tubing and hydraulic tubing; secure hydraulic tubes 
with additional clamps, inspect adjacent fuel tubing for 
interference with the hydraulic tubing, replace the left engine 
hydraulic pump case drain tube on certain airplanes, and do all 
applicable corrective actions.
    (3) Do a general visual inspection for clearance between the 
left engine hydraulic

[[Page 51705]]

tubing with adjacent tubing, structure, and other components.
    (4) Do a general visual inspection for clearance between the 
wire harnesses and the hydraulic and fuel tubing on the left engine.
    (5) Do a general visual inspection for clearance between the 
wire harnesses and the hydraulic and fuel tubing on the right 
engine.

Alternative Methods of Compliance (AMOCs)

    (n)(1) The Manager, Wichita 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. Send information to 
ATTN: James Galstad, Aerospace Engineer, Systems and Propulsion 
Branch, ACE-116W, FAA, Wichita ACO, 1801 Airport Road, Room 100, 
Mid-Continent Airport, Wichita, Kansas 67209; telephone (316) 946-
4135; fax (316) 946-4107.
    (2) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Before using any approved AMOC on any airplane to which the AMOC 
applies, notify your principal maintenance inspector (PMI) or 
principal avionics inspector (PAI), as appropriate, or lacking a 
principal inspector, your local Flight Standards District Office. 
The AMOC approval letter must specifically reference this AD.
    (3) AMOCs approved previously in accordance with AD 2009-11-13, 
amendment 39-15923, are approved as AMOCs for the corresponding 
provisions of this AD.

    Issued in Renton, Washington, on August 16, 2010.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2010-20853 Filed 8-20-10; 8:45 am]
BILLING CODE 4910-13-P
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