AD 2009-12-13

We are adopting a new airworthiness directive (AD) for the products listed above. This 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:

There has been one case reported of failure of a shaft (tailstock) on an elevator Power Control Unit (PCU), Part Number (P/ N) 390600-1007. Continued actuation of the affected PCU caused damage to the surrounding structure. * * *

Each elevator surface has three PCUs, powered by separate independent hydraulic systems, and a single elevator PCU shaft failure may remain dormant. Such a dormant loss of redundancy, coupled with the potential for a failed shaft to produce collateral damage, including damage to hydraulic lines, could possibly affect the controllability of the aircraft.

* * * * * This AD requires actions that are intended to address the unsafe condition described in the MCAI.

Final rule; request for comments.

2009-12-13 Bombardier, Inc. (Formerly de Havilland, Inc.): Amendment 39-15936. Docket No. FAA-2009-0530; Directorate Identifier 2009-NM- 079-AD.

Effective Date

(a) This airworthiness directive (AD) becomes effective June 26, 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 4135 through 4149 inclusive.

Subject

(d) Air Transport Association (ATA) of America Code 27: Flight Controls.

Reason

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

There has been one case reported of failure of a shaft (tailstock) on an elevator Power Control Unit (PCU), Part Number (P/ N) 390600-1007. Continued actuation of the affected PCU caused damage to the surrounding structure. Subsequent investigation determined that the failure was the result of a material defect and that the shafts installed on a total of 88 suspect PCUs * * * may contain a similar defect.

Each elevator surface has three PCUs, powered by separate independent hydraulic systems, and a single elevator PCU shaft failure may remain dormant. Such a dormant loss of redundancy, coupled with the potential for a failed shaft to produce collateral damage, including damage to hydraulic lines, could possibly affect the controllability of the aircraft.

This directive mandates an identification check for elevator PCU serial numbers, a daily check for correct operation of all suspect PCUs and, finally, replacement of all suspect PCUs.

Actions and Compliance

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

(1) Within 30 days after the effective date of this AD, inspect the serial number of each of the six installed elevator PCUs having P/N 390600-1007. If one or more of the six installed elevator PCUs, P/N 390600-1007, have any of the PCU serial numbers 238, 698, 783 through 788 inclusive, 790, 793, 795, 802, 806, 807, 810, 820 through 823 inclusive, 826 through 828 inclusive, 831, 835, 838, 840, 886 through 889 inclusive, or 898 through 955 inclusive; without a suffix "A'' after the serial number: Within 30 days after the effective date of this AD, perform a check for the correct operation of all installed elevator PCUs in accordance with the procedures detailed in Appendix A, B, or C of Bombardier Q400 All Operator Message 217B, dated April 26, 2007. Repeat the check thereafter before the first flight of each day until the replacement specified in paragraph (f)(3) of this AD is done. The checks in Appendix A and B of Bombardier Q400 All Operator Message 217B, dated April 26, 2007, must be performed by the flight crew, while the check specified in Appendix C of the all operators message must be performed by certificated maintenance personnel.

Note 1: Suffix "A'' after the serial number indicates that the PCU has already passed a magnetic particle inspection and is cleared for continued use.(2) If incorrect operation of any elevator PCU is found during any check required by paragraph (f)(1) of this AD, before further flight, replace the elevator PCU with a PCU, P/N 390600-1007, having a serial number not specified in paragraph (f)(1) of this AD; or with a PCU, P/N 390600-1007, having the suffix "A'' after the serial number; in accordance with the Accomplishment Instructions of Bombardier Service Bulletin 84-27-32, Revision A, dated January 18, 2008.

(3) Replacing all PCUs, P/N 390600-1007, having a serial number specified in paragraph (f)(1) of this AD, and not having suffix "A'' after the serial number, with a PCU, P/N 390600-1007, having a serial number not specified in paragraph (f)(1) of this AD; or with a PCU, P/N 390600-1007, having the suffix "A'' after the serial number; in accordance with the Accomplishment Instructions of Bombardier Service Bulletin 84-27-32, Revision A, dated January 18, 2008; terminates the requirements of paragraph (f)(1) of this AD.

(4) Actions accomplished before the effective date of this AD according to Bombardier Service Bulletin 84-27-32, dated May 1, 2007, are considered acceptable for compliance with the corresponding action specified in this AD.

FAA AD Differences

Note 2: This AD differs from the MCAI and/or service information as follows: Unlike the Canadian airworthiness directive CF-2009-16, dated April 20, 2009, this AD does not require the eventual replacement of all elevator PCUs identified in paragraph (f)(1) of this AD. The planned compliance times for those actions would allow enough time to provide notice and opportunity for prior public comment on the merits of those actions. Therefore, we are considering further rulemaking to address this issue.

Other FAA AD Provisions

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

(1) Alternative Methods of Compliance (AMOCs): The Manager, Airframe and Propulsion Branch, ANE-171, 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: Cesar Gomez, Aerospace Engineer, Airframe and Propulsion Branch, ANE-171, FAA, New York Aircraft Certification Office, 1600 Stewart Avenue, Suite 410, Westbury, New York 11590; telephone (516) 228-7318; 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. The AMOC approval letter must specifically reference this AD.

(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-2009-16, dated April 20, 2009; Bombardier Service Bulletin 84-27-32, Revision A, dated January 18, 2008; and Bombardier Q400 All Operator Message 217B, dated April 26, 2007; for related information.

Material Incorporated by Reference

(i) You must use Bombardier Service Bulletin 84-27-32, Revision A, dated January 18, 2008, or Bombardier Q400 All Operator Message 217B, dated April 26, 2007 to do the actions required by this AD, unless the AD specifies otherwise.

(1) The Director of the Federal Register approved the incorporation by reference of this service information under 5 U.S.C. 552(a) and 1 CFR part 51.

(2) For service information identified in this AD, contact Bombardier, Inc., 400 C[ocirc]te-Vertu Road West, Dorval, Qu[eacute]bec H4S 1Y9, Canada; telephone 514-855-5000; fax 514-855- 7401; e-mail thd.qseries@aero.bombardier.com; Internet http:// www.bombardier.com.

(3) You may review copies of the 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.

(4) You may also review copies of the service information that is incorporated by reference at the National Archives and

Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http:// www.archives.gov/federal_register/code_of_federal_regulations/ ibr_locations.html.

Discussion

Transport Canada Civil Aviation (TCCA), which is the aviation authority for Canada, has issued Canadian Airworthiness Directive CF- 2009-16, dated April 20, 2009 (referred to after this as "the MCAI''), to correct an unsafe condition for the specified products. The MCAI states:

There has been one case reported of failure of a shaft (tailstock) on an elevator Power Control Unit (PCU), Part Number (P/ N) 390600-1007. Continued actuation of the affected PCU caused damage to the surrounding structure. Subsequent investigation determined that the failure was the result of a material defect and that the shafts installed on a total of 88 suspect PCUs * * * may contain a similar defect.

Each elevator surface has three PCUs, powered by separate independent hydraulic systems, and a single elevator PCU shaft failure may remain dormant. Such a dormant loss of redundancy, coupled with the potential for a failed shaft to produce collateral damage, including damage to hydraulic lines, could possibly affect the controllability of the aircraft.

This directive mandates an identification check for elevator PCU serial numbers, a daily check for correct operation of all suspect PCUs and, finally, replacement of all suspect PCUs.

You may obtain further information by examining the MCAI in the AD docket.

Relevant Service Information

Bombardier has issued Service Bulletin 84-27-32, Revision A, dated January 18, 2008; and Q400 All Operator Message 217B, dated April 26, 2007. 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 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 issuing this AD because we evaluated all pertinent information and determined the unsafe condition exists and is likely to exist or develop on other products of the same type design.

Differences Between the 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 required 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 AD.

FAA's Determination of the Effective Date

An unsafe condition exists that requires the immediate adoption of this AD. The FAA has found that the risk to the flying public justifies waiving notice and comment prior to adoption of this rule because the power control unit (PCU), part number P/N 390600-1007, has been identified as having a shaft (tailstock) failure. Each elevator on the affected model airplane contains three PCUs which are powered independently as a means of redundancy. Due to this built-in redundancy, a fracture to the elevator PCU shaft can remain undetected while decreasing airplane safety. Furthermore, the continual use of the failed shaft in the PCUs can result in damage to additional systems such as hydraulic lines, and could result in loss of controllability of the airplane. Since this is a dormant failure, it is necessary to identify and replace any defective units within 30 days after the effective date of this AD. Therefore, we determined that notice and opportunity for public comment before issuing this AD are impracticable and that good cause exists for making this amendment effective in fewer than 30 days.

Comments Invited

This AD is a final rule that involves requirements affecting flight safety, and we did not precede it by notice and opportunity for public comment. We invite you to send any written relevant data, views, or arguments about this AD. Send your comments to an address listed under the ADDRESSES section. Include "Docket No. FAA-2009-0530; Directorate Identifier 2009-NM-079-AD'' at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this AD. We will consider all comments received by the closing date and may amend this 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 AD.

Authority for This Rulemaking

Title 49 of the United States Codespecifies 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 AD will not have federalism implications under Executive Order 13132. This AD will 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 AD:

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 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.

Adoption of the Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 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 adding the following new AD: