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###### Department of Transportation

###### Federal Aviation Administration

          - 14 CFR Part 39
          - [Docket No. FAA-2009-0526; Directorate Identifier 2009-NM-029-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 the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:

Four aircraft have experienced a dual AC generator shutdown, caused by a broken propeller de-ice bus bar which short-circuited with the backplate assembly. 

* * * A short circuit can cause a dual AC generator shutdown that, particularly in conjunction with an engine failure in icing conditions, could result in reduced controllability of the aircraft. 

* * * * *

Reduced controllability of the airplane in certain operating conditions affects continued safe flight and landing. The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.

# DATES:

We must receive comments on this proposed AD by July 10, 2009.

# 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, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.                    

                        For service information identified in this proposed AD, contact Bombardier, Inc., 400 Côte-Vertu Road West, Dorval, Québec H4S 1Y9, Canada; telephone 514-855-5000; fax 514-855-7401; e-mail                         *thd.qseries@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 or 425-227-1152.                    

## Examining the AD Docket

                    You may examine the AD docket on the Internet at                     *http://www.regulations.gov;*                     or in person at the Docket Operations office 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 Operations 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:

Wing Chan, Aerospace Engineer, Aerospace Engineer, Systems and Flight Test Branch, ANE-172, FAA, New York Aircraft Certification Office, 1600 Stewart Avenue, Suite 410, Westbury, New York 11590; telephone (516) 228-7311; fax (516) 794-5531.

# 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-2009-0526; Directorate Identifier 2009-NM-029-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 based on 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

Transport Canada Civil Aviation (TCCA), which is the aviation authority for Canada, has issued Canadian Airworthiness Directive CF-2009-01, dated January 19, 2009 (referred to after this as “the MCAI”), to correct an unsafe condition for the specified products. The MCAI states:

Four aircraft have experienced a dual AC generator shutdown, caused by a broken propeller de-ice bus bar which short-circuited with the backplate assembly.

It was subsequently determined that any friction or contact between a propeller de-ice bus bar and the backplate assembly can cause an intermittent short circuit. Such a short circuit can cause a dual AC generator shutdown that, particularly in conjunction with an engine failure in icing conditions, could result in reduced controllability of the aircraft.

                        This directive mandates revision of the Airplane Flight Manual (AFM) to introduce a procedure that restores AC power following a failure of No. 1 and No. 2 AC generators with propeller de-ice on. Additionally, in                               ( print page 27477)                            order to prevent similar dual AC generator shutdowns, it mandates the application of sealant as insulation between the propeller de-ice bus bars and the backplate assembly.                    

Reduced controllability of the airplane in certain operating conditions affects continued safe flight and landing. You may obtain further information by examining the MCAI in the AD docket.

## Relevant Service Information

Bombardier has issued Service Bulletin 84-61-03, Revision `A,' dated September 18, 2008; and Bombardier Temporary Amendment (TA) 14, Issue 1, dated May 10, 2006, to the Dash 8 Q400 Airplane Flight Manual PSM 1-84-1A. The actions described in this service information are intended to correct the unsafe condition identified in the MCAI.

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

This product has been approved by the aviation authority of another country, and is approved for operation in the United States. Pursuant to our bilateral agreement with the State of Design Authority, we have been notified of the unsafe condition described in the MCAI and service information referenced above. We are proposing this AD because we evaluated all pertinent information and determined an unsafe condition exists and is likely to exist or develop on other products of the same type design.

## Differences Between This AD and the MCAI or Service Information

We have reviewed the MCAI and related service information and, in general, agree with their substance. But we might have found it necessary to use different words from those in the MCAI to ensure the AD is clear for U.S. operators and is enforceable. In making these changes, we do not intend to differ substantively from the information provided in the MCAI and related service information.

We might also have proposed different actions in this AD from those in the MCAI in order to follow FAA policies. Any such differences are highlighted in a NOTE within the proposed AD.

## Costs of Compliance

Based on the service information, we estimate that this proposed AD would affect about 62 products of U.S. registry. We also estimate that it would take about 6 work-hours per product to comply with the basic requirements of this proposed AD. The average labor rate is $80 per work-hour. Based on these figures, we estimate the cost of the proposed AD on U.S. operators to be $29,760, or $480 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.

We prepared a regulatory evaluation of the estimated costs to comply with this proposed AD and placed it in the AD docket.

# 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:

**Bombardier, Inc. (Formerly de Havilland, Inc.):**                                 Docket No. FAA-2009-0526; Directorate Identifier 2009-NM-029-AD.                            

## Comments Due Date

(a) We must receive comments by July 10, 2009.

## Affected ADs

(b) None.

## Applicability

(c) This AD applies to Bombardier Model DHC-8-400, DHC-8-401, and DHC-8-402 airplanes, certificated in any category, serial numbers 4001, 4003, 4004, 4006, and 4008 through 4154 inclusive.

## Subject

(d) Air Transport Association (ATA) of America Code 61: Propellers/Propulsors.

## Reason

(e) The mandatory continuing airworthiness information (MCAI) states:

Four aircraft have experienced a dual AC generator shutdown, caused by a broken propeller de-ice bus bar which short-circuited with the backplate assembly.

It was subsequently determined that any friction or contact between a propeller de-ice bus bar and the backplate assembly can cause an intermittent short circuit. Such a short circuit can cause a dual AC generator shutdown that, particularly in conjunction with an engine failure in icing conditions, could result in reduced controllability of the aircraft.

This directive mandates revision of the Airplane Flight Manual (AFM) to introduce a procedure that restores AC power following a failure of No. 1 and No. 2 AC generators with propeller de-ice on. Additionally, in order to prevent similar dual AC generator shutdowns, it mandates the application of sealant as insulation between the propeller de-ice bus bars and the backplate assembly.

Reduced controllability of the airplane in certain operating conditions affects continued safe flight and landing.

## Actions and Compliance

(f) Unless already done, do the following actions.

                                (1) Within 30 days after the effective date of this AD, revise the Limitations section of the AFM by inserting a copy of Bombardier Temporary Amendment (TA) 14, Issue 1, dated May 10, 2006, to the Dash 8 Q400 AFM PSM 1-84-1A. When the information in Bombardier TA 14, Issue 1, dated May 10, 2006, is included in the general revisions of the AFM, the general revisions may be inserted in the AFM and the TA may be removed.                                      ( print page 27478)    

(2) Within 5,000 flight hours after the effective date of this AD: Apply sealant between the bus bar assemblies and the backplate assembly by incorporating Modsum 4W163047, Revision B, dated August 11, 2008, in accordance with the Accomplishment Instructions of Bombardier Service Bulletin 84-61-03, Revision `A,' dated September 18, 2008.

(3) Incorporating Bombardier DHC-8-S400 Modification Summary Package 4W163047 before the effective date of this AD in accordance with Bombardier Service Bulletin 84-61-03, dated April 27, 2007, is considered acceptable for compliance with the requirements of paragraph (f)(2) of this AD.

## FAA AD Differences

# Note 1: 

This AD differs from the MCAI and/or service information as follows: No differences.

## Other FAA AD Provisions

(g) The following provisions also apply to this AD:

                                (1)                                 *Alternative Methods of Compliance (AMOCs):*                                 The Manager, New York 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: Wing Chan, Aerospace Engineer, Aerospace Engineer, Systems and Flight Test Branch, ANE-172, FAA, New York ACO, 1600 Stewart Avenue, Suite 410, Westbury, New York 11590; telephone (516) 228-7311; fax (516) 794-5531. 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.                            

                                (2)                                 *Airworthy Product:*                                 For any requirement in this AD to obtain corrective actions from a manufacturer or other source, use these actions if they are FAA-approved. Corrective actions are considered FAA-approved if they are approved by the State of Design Authority (or their delegated agent). You are required to assure the product is airworthy before it is returned to service.                            

                                (3)                                 *Reporting Requirements:*                                 For any reporting requirement in this AD, under the provisions of the Paperwork Reduction Act, the Office of Management and Budget (OMB) has approved the information collection requirements and has assigned OMB Control Number 2120-0056.                            

## Related Information

(h) Refer to MCAI Canadian Airworthiness Directive CF-2009-01, dated January 19, 2009; and Bombardier Service Bulletin 84-61-03, Revision `A,' dated September 18, 2008; for related information.

Issued in Renton, Washington, on June 2, 2009.

Stephen P. Boyd,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

[FR Doc. E9-13505 Filed 6-9-09; 8:45 am]

BILLING CODE 4910-13-P