AD 2008-03-01

We are superseding an existing airworthiness directive (AD) for the products listed above. This AD results from mandatory continuing airworthiness information (MCAI) issued 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:

Certain structural components must be replaced by new components at a certain stage of the aircraft's life to avoid any possibility of fatigue failure.

We are issuing this AD to require actions to correct the unsafe condition on these products.

Final rule.

2008-03-01 Viking Air Limited: Amendment 39-15350; Docket No. FAA- 2007-27192; Directorate Identifier 2007-CE-008-AD.

Effective Date

(a) This airworthiness directive (AD) becomes effective March 6, 2008.

Affected ADs

(b) This AD supersedes AD 83-02-02, Amendment 39-4553.

Applicability

(c) This AD applies to Models DHC-6-1, DHC-6-100, DHC-6-200, and DHC-6-300 airplanes, all serial numbers, certificated in any category.

Subject

(d) Air Transport Association of America (ATA) Code 51: Structures.

Reason

(e) The mandatory continuing airworthiness information (MCAI) refers to the Product Support Manual (PSM) 1-6-11, Revision 5, dated January 11, 2000, which states:

Certain structural components must be replaced by new components at a certain stage of the aircraft's life to avoid any possibility of fatigue failure.

The MCAI requires you to inspect, modify, and/or retire affected structural components to maintain the structural integrityof DHC-6 airplanes.

Actions and Compliance

(f) Unless already done, within 30 days after March 6, 2008 (the effective date of this AD), for all aircraft, incorporate the inspections, modifications, and/or retirement of components specified in Bombardier Inc.(formerly de Havilland) DHC-6 "Twin Otter'' PSM 1-6-11, Revision 6, dated March 28, 2007, into the aircraft maintenance program. The compliance times are specified in the manual. For aircraft that are approaching or have exceeded the threshold of the new or revised inspections introduced by this AD, compliance with the threshold inspection may be modified as detailed below:
(1) Pre Mod 6/1117 Wing Assemblies:

(i) If the last inspection done of the main wing spar attachment lug fastener holes, before March 6, 2008 (the effective date of this AD), was an eddy current inspection following Bombardier Inc. (formerly de Havilland) DHC-6 "Twin Otter'' PSM 1-6-11, Revision 5, dated January 11, 2000; or PSM 1-6-11, Revision6, dated March 28, 2007; do the repeat high frequency eddy current inspection in accordance with the schedule in PSM 1-6-11, Revision 6, dated March 28, 2007.

(ii) If the last inspection done of the main wing spar attachment lug fastener holes, before March 6, 2008 (the effective date of this AD), was an ultrasonic inspection following Bombardier Service Bulletin 6/525, dated September 6, 1996, do the first high frequency eddy current inspection within 1,000 hours time-in-service (TIS) or 2000 cycles, whichever occurs first, after the last ultrasonic inspection. Repetitively inspect thereafter in accordance with the schedule in PSM 1-6-11, dated March 28, 2007.

Note 1: Operators that do not have landing (or cycle) records may determine the number of landings (or cycles) by dividing the number of hours of time-in-service of each airplane by the time of the average flight for the aircraft of that type in the operator's fleet.

(2) Post Mod 6/1117 and Post Mod 6/1630 Wing Assemblies: If the inspection threshold for the lower wing skin, stringers, and aft spar lower flange WS122 to WS263 (ribs 8 to 20) has been exceeded or will be exceeded within 6 months after March 6, 2008 (the effective date of this AD), do the first high frequency eddy current inspection within the next 500 hours TIS after March 6, 2008 (the effective date of this AD), or within the next 6 months after March 6, 2008 (the effective date of this AD), whichever occurs first, following PSM 1-6-11, Revision 6, dated March 28, 2007.

(g) You may take "unless already done'' credit if the above actions were done following the procedures described in Bombardier Inc. (formerly de Havilland) DHC-6 "Twin Otter'' PSM 1-6-11, Revision 5, dated January 11, 2000.

FAA AD Differences

Note 2: This AD differs from the MCAI and/or service information as follows: The MCAI references PSM 1-6-11, Revision 5, dated January 11, 2000. PSM 1-6-11, Revision 6, dated March 28, 2007, has since been issued and is referenced for compliance in this AD.

Other FAA AD Provisions

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

(1) Alternative Methods of Compliance (AMOCs): The Manager, New York Aircraft Certification Office, 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: George Duckett, Aerospace Engineer, Airframe and Propulsion Branch, FAA, New York Certification Office, 1600 Stewart Avenue, suite 410, Westbury, New York 11590; telephone: (516) 228-7325; fax: (516) 794-5531. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO.

(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 (44 U.S.C. 3501 et. seq.), the Office of Management and Budget (OMB) has approved the information collection requirements and has assigned OMB Control Number 2120-0056.

Related Information

(i) Refer to MCAI Transport Canada AD No. CF-2000-14, dated May 25, 2000; and Viking Air Limited Structural Components Service Life Limits Manual PSM 1-6-11, Revision 6, dated March 28, 2007, for related information.

Material Incorporated by Reference

(j) You must use PSM 1-6-11, Revision 6, dated March 28, 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 serviceinformation under 5 U.S.C. 552(a) and 1 CFR part 51.

(2) For service information identified in this AD, contact Bombardier Inc., Bombardier Regional Aircraft Division, Garratt Boulevard, Downsview, Ontario, Canada M3K 1Y5; telephone: (416) 633- 7310.

(3) You may review copies at the FAA, Central Region, Office of the Regional Counsel, 901 Locust, Room 506, Kansas City, Missouri 64106; or 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

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to the specified products. That NPRM was published in the Federal Register on November 14, 2007 (72 FR 64010) and proposed to supersede AD 83-02-02, Amendment 39-4553. That NPRM proposed to correct an unsafe condition for the specified products. The MCAI states that:

Certain structural components must be replaced by new components at a certain stage of the aircraft's life to avoid any possibility of fatigue failure.

Comments

We gave the public the opportunity to participate in developing this AD. We received no comments on the NPRM or on the determination of the cost to the public.

Conclusion

We reviewed the available data and determined that air safety and the public interest require adopting the AD as proposed.

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 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.

Costs of Compliance

We estimate that this AD will affect 166 products of U.S. registry. We also estimate that it will take about 30 work-hours per product to comply with basic requirements of this AD. The average labor rate is $80 per work-hour. Required parts will cost about $988 per product. Based on these figures, we estimate the cost of this AD to the U.S. operators to be $562,408 or $3,388 per product.

Authority for This RulemakingTitle 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 AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial directeffect 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 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.

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 the NPRM, 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.

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 removing Amendment 39-4553 (AD 83-02- 02, February 4, 1983) and adding the following new AD: