2010-20853. Airworthiness Directives; Learjet Inc. Model 45 Airplanes

AGENCY:

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

ACTION:

Notice of proposed rulemaking (NPRM).

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: [phone].
• 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: [phone]; fax: [phone]; e-mail: [e-mail]; 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 [phone]) 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 [phone]; fax [phone].

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.

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.

Estimated Costs

Action	Work hours	Average labor rate per hour	Parts	Cost per airplane	Number of U.S.- registered airplanes	Fleet cost
Inspection (required by AD 2009-11-13)	3	$85	$0	$255 per inspection	325	$82,875 per inspection.
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.

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.

§ 39.13

[Amended]

2. The FAA amends § 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 inclusive (commonly referred to as “M45” airplanes)	Bombardier Alert Service Bulletin A45-29-15, dated December 26, 2006.
Serial numbers 45-2001 through 45-2063 inclusive (commonly referred to as “M40” airplanes)	Bombardier Alert Service Bulletin A40-29-03, dated December 26, 2006.

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 inclusive (commonly referred to as “M40” airplanes)	Learjet 40 TR 71-1, dated April 28, 2009, to the Learjet 40 Maintenance Manual MM-105.
Serial numbers 45-002 through 45-2000 inclusive (commonly referred to as “M45” airplanes)	Learjet 45 TR 71-1, dated April 28, 2009, to the Learjet 45 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 inclusive (commonly referred to as “M45” airplanes)	Section 71-00-00, “Powerplant—Maintenance Practices,” and 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 inclusive (commonly referred to as “M40” airplanes)	Section 71-00-01, “Engine—Maintenance Practices,” of 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 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 [phone]; fax [phone].

(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.