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###### Department of Transportation

###### Federal Aviation Administration

          - 14 CFR Part 39
          - [Docket No. FAA-2010-0951; Directorate Identifier 2010-NM-107-AD]
          - RIN 2120-AA64

# AGENCY:

Federal Aviation Administration (FAA), DOT.

# ACTION:

Notice of proposed rulemaking (NPRM).

# SUMMARY:

We propose to adopt a new airworthiness directive (AD) for all Model 45 airplanes. This proposed AD would require a general visual inspection for damage of wiring (including chafing, pinched wires, and exposed wires) and correct routing of wires in the left and right circuit breaker panels, and related investigative and corrective actions if necessary. This proposed AD results from reports of wire damage on the pilot and copilot circuit breaker panels caused by a short circuit between chafed wires. We are proposing this AD to detect and correct damaged or misrouted wires, which could result in a short circuit and the loss of systems associated with the wiring (including fire suppression function for one engine and essential avionics systems).

# DATES:

We must receive comments on this proposed AD by November 15, 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.                               ( print page 60668)      
      -  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:

Kevin Schwemmer, Aerospace Engineer, Electrical Systems and Avionics, ACE-119W, FAA, Wichita Aircraft Certification Office (ACO), 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209; telephone (316) 946-4174; 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-2010-0951; Directorate Identifier 2010-NM-107-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 a wire failure associated with the pilot and copilot circuit breaker panel that could result in toxic gases in the crew compartment. Wire damage caused by a short circuit and subsequent burning of wires have been reported on four Model 45 airplanes. In all four incidents, the wire damage was associated with the 28 volts direct current (VDC) power for the fire-suppression system. This condition, if not corrected, could result in wire damage caused by a short circuit, which could result in the loss of systems associated with the wiring (including fire suppression function for one engine and essential avionics systems).

## Relevant Service Information

We have reviewed Bombardier Alert Service Bulletin A40-24-11, dated November 16, 2009; and Bombardier Alert Service Bulletin A45-24-16, dated November 16, 2009. The service information describes procedures for doing a general visual inspection for damage of wiring (including chafing, pinched wires, and exposed wires) and correct routing of wires in the left and right circuit breaker panels, and related investigative and corrective actions, if necessary. The related investigative action is doing a general visual inspection for arcing damage on the mounting brackets of the forward circuit breaker panel. Depending on inspection findings, the corrective actions are replacing damaged (chafed, pinched, or exposed) wires, and re-routing any incorrectly routed wires; and contacting the manufacturer for repair instructions and doing the repair.

## FAA's Determination and Requirements of This Proposed AD

We are proposing this AD because we evaluated all relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design. This proposed AD would require accomplishing the actions specified in the service information described previously, except as discussed under “Differences Between the Proposed AD and Service Bulletin.”

## Differences Between the Proposed AD and Service Bulletin

Although Bombardier Alert Service Bulletin A40-24-11, dated November 16, 2009; and Bombardier Alert Service Bulletin A45-24-16, dated November 16, 2009; specify that operators may contact the manufacturer for disposition of certain repair conditions, this proposed AD would require operators to repair those conditions using a method approved by the FAA.

## Costs of Compliance

We estimate that this proposed AD would affect 339 airplanes of U.S. registry. We also estimate that it would take about 1 work-hour per product to comply with this proposed AD. The average labor rate is $85 per work-hour. Based on these figures, we estimate the cost of this proposed AD to the U.S. operators to be $28,815, or $85 per product.

## 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), 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.

You can find our regulatory evaluation and the estimated costs of compliance in the AD Docket.

      ( print page 60669)    

# 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 

2. The FAA amends § 39.13 by adding the following new AD:

**Learjet Inc.:**                                 Docket No. FAA-2010-0951; Directorate Identifier 2010-NM-107-AD.                            

## Comments Due Date

(a) We must receive comments by November 15, 2010.

## Affected ADs

(b) None.

## Applicability

(c) This AD applies to Learjet Inc. Model 45 airplanes, certificated in any category; having serial numbers identified in paragraphs (c)(1) and (c)(2) of this AD.

(1) Serial numbers 45-2001 through 45-2114 inclusive, 45-2116 through 45-2120 inclusive, 45-2122, 45-2125, and 45-2126.

(2) Serial numbers 45-005 through 45-380 inclusive, 45-382 through 45-391 inclusive, 45-393 through 45-396 inclusive, 45-398, 45-400, 45-401, and 45-403.

## Subject

(d) Air Transport Association (ATA) of America Code 24: Electrical power.

## Unsafe Condition

(e) This AD results from reports of wire damage on the pilot and copilot circuit breaker panels caused by a short circuit between chafed wires. The Federal Aviation Administration is issuing this AD to detect and correct damaged or misrouted wires, which could result in a short circuit and the loss of systems associated with the wiring (including fire suppression function for one engine and essential avionics systems).

## 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.

## Inspection and Corrective Action

(g) Within 50 flight hours after the effective date of this AD: Do a general visual inspection for damage of wiring and correct routing of wires in the left and right circuit breaker panels, and all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Bombardier Alert Service Bulletin A40-24-11, dated November 16, 2009; or Bombardier Alert Service Bulletin A45-24-16, dated November 16, 2009; as applicable; except if arcing damage is found on the mounting brackets of the forward circuit breaker panel, before further flight, repair in accordance with a method approved by the Manager, Wichita Aircraft Certification Office, FAA. Do all applicable related investigative and corrective actions before further flight.

# Note 1:

For the purposes of this AD, a general visual inspection is: “A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to ensure visual access to all surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or droplight and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.”

## Alternative Methods of Compliance (AMOCs)

(h)(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: Kevin Schwemmer, Aerospace Engineer, Electrical Systems and Avionics, ACE-119W, FAA, Wichita Aircraft Certification Office (ACO), 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209; telephone (316) 946-4174; 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.

Issued in Renton, Washington, on September 24, 2010.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.

[FR Doc. 2010-24713 Filed 9-30-10; 8:45 am]

BILLING CODE 4910-13-P