AD 2009-26-05

We are adopting a new 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:

This Airworthiness Directive (AD) is prompted due to the discovery of cracks caused by stress corrosion in the main-gear support struts. All the main-gear support struts that had cracks were made from material AA2024-T351 which has a lower resistance to stress corrosion cracking.

Such cracks, if undetected, could lead to the failure of the strut during landing which could then cause the Main Landing Gear (MLG) to collapse.

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

Final rule.

2009-26-05 Pilatus Aircraft Ltd: Amendment 39-16140; Docket No. FAA- 2009-0938; Directorate Identifier 2009-CE-052-AD.

Effective Date

(a) This airworthiness directive (AD) becomes effective February 1, 2010.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Model PC-7 airplanes, manufacturer serial numbers 101 through 618 that are:

(1) Equipped with main-gear support struts part number (P/N) 532.10.09.039 or P/N 114.48.07.127; and

(2) Certificated in any category.

Subject

(d) Air Transport Association of America (ATA) Code 32: Landing Gear.

Reason

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

This Airworthiness Directive (AD) is prompted due to the discovery of cracks caused by stress corrosion in the main-gear support struts. All the main-gear support struts that had cracks were made from material AA2024-T351 which has a lower resistance to stress corrosion cracking.

Such cracks, if undetected, could lead to the failure of the strut during landing which could then cause the Main Landing Gear (MLG) to collapse.

In order to correct and control the situation, this AD mandates the identification of the main-gear support struts to check if they have rounded clevis lugs and a Non-Destructive Inspection (NDI) procedure on the main-gear support struts if they have chamfered clevis lugs.

For main-gear support struts with chamfered clevis lugs that show cracks during the NDI, the MCAI also requires replacing any cracked main-gear support struts with parts of improved design. You may obtain further information by examining the MCAI in the AD docket.

Actions and Compliance

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

(1) Within the next 30 hours time-in-service (TIS) after February 1, 2010 (the effective date of this AD) or within the next 30 days after February 1, 2010 (the effective date of this AD), whichever occurs first, visually inspect the leftand right main- gear support struts to determine if they have rounded or chamfered clevis lugs. Do the inspection following paragraph 3.A. of Pilatus PC-7 Service Bulletin No. 32-024, Rev. No. 1, dated November 17, 2008.

(2) Based on the results of the inspection required in paragraph (f)(1) of this AD, if the main-gear support strut has rounded clevis lugs, no further action is required except the requirement specified in paragraph (f)(4) of this AD still applies. Make an entry in the airplane logbook to show compliance with this AD. Based on the reports of the results of the inspection required by this AD, further rulemaking action may be taken to mandate repetitive inspections or terminating action.

(3) Based on the results of the inspection required in paragraph (f)(1) of this AD, if the main-gear support strut has chamfered clevis lugs, before further flight do a Non-Destructive Inspection (NDI). Do the NDI following paragraphs 3.B. through 3.E. of Pilatus PC-7 Service Bulletin No. 32-024, Rev. No. 1, dated November 17, 2008.

(i) If cracks are found during the inspection required in paragraph (f)(3) of this AD:

(A) Before further flight after the inspection, replace any cracked main-gear support struts with new main-gear support struts, P/N 532.10.09.128. Do the replacement following Pilatus PC-7 Service Bulletin No. 32-025, Rev. No. 1, dated November 17, 2008.

(B) Within the next 10 days after the inspection, report the cracks to Pilatus Aircraft LTD., Customer Liaison Manager, CH-6371 STANS, Switzerland, using the Crack Report Form (Figure 4) in Pilatus PC-7 Service Bulletin No. 32-024, Rev. No. 1, dated November 17, 2008.

(ii) If no cracks are found during the inspection required in paragraph (f)(3) of this AD, no further action is required. Make an entry in the airplane logbook to show compliance with this AD.

(4) As of 30 days after February 1, 2010 (the effective date of this AD), do not install any main-gear support struts, P/N 532.10.09.039 or P/N 114.48.07.127, with chamfered clevis lugs.

Note 1: If you have any main-gear support struts, P/N 532.10.09.039 or P/N 114.48.07.127, with chamfered clevis lugs held as spares, you may return them to Pilatus Aircraft Ltd., Customer Liaison Manager, CH-6371 STANS, Switzerland, for replacement with a new main-gear support strut, P/N 532.10.09.128.

FAA AD Differences

Note 2: 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, Standards 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: Doug Rudolph, Aerospace Engineer, FAA, Small Airplane Directorate, 901 Locust, Room 301, Kansas City, Missouri 64106; telephone: (816) 329-4059; fax: (816) 329-4090; e-mail: doug.rudolph@faa.gov. 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

(h) Refer to MCAI Federal Office of Civil Aviation AD HB-2009- 011, dated September 10, 2009; and Pilatus PC-7 Service Bulletin No. 32-024, Rev. No. 1, dated November 17, 2008; and Pilatus PC-7 Service Bulletin No. 32-025, Rev. No. 1, dated November 17, 2008, for related information.

Material Incorporated by Reference

(i) You must use Pilatus PC-7 Service Bulletin No. 32-024, Rev. No. 1, dated November 17, 2008; and Pilatus PC-7 Service Bulletin No. 32-025, Rev. No. 1, dated November 17, 2008, 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 Pilatus Aircraft LTD., Customer Service Manager, CH-6371 STANS, Switzerland; telephone: +41 (0)41 619 62 08; fax: +41 (0)41 619 73 11; Internet: http://www.pilatus-aircraft.com/, or e-mail: snolan@pilatus-aircraft.com.

(3) You may review copies of the service informationincorporated by reference for this AD at the FAA, Central Region, Office of the Regional Counsel, 901 Locust, Kansas City, Missouri 64106. For information on the availability of this material at the Central Region, call (816) 329-3768.

(4) You may also review copies of the service information incorporated by reference for this AD 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 October 9, 2009 (74 FR 52156). That NPRM proposed to correct an unsafe condition for the specified products. The MCAI states:

This Airworthiness Directive (AD) is prompted due to the discovery of cracks caused by stress corrosion in the main-gear support struts. All the main-gear support struts that had cracks were made from material AA2024-T351 which has a lower resistance to stress corrosion cracking.

Such cracks, if undetected, could lead to the failure of the strut during landing which could then cause the Main Landing Gear (MLG) to collapse.

In order to correct and control the situation, this AD mandates the identification of the main-gear support struts to check if they have rounded clevis lugs and a Non-Destructive Inspection (NDI) procedure on the main-gear support struts if they have chamfered clevis lugs.

For main-gear support struts with chamfered clevis lugs that show cracks during the NDI, the MCAI also requires replacing any cracked main-gear support struts with parts of improved design. You may obtain further information by examining the MCAI in the AD docket.

Comments

We gave the public the opportunity to participate in developing this AD. We considered the comment received.

PILATUS Aircraft Ltd. states that there is a typographical error in one of the affected part numbers (P/N) referenced in the proposed AD. The P/N should read 114.48.07.127 instead of 114.48.07.172.

We agree with the commenter and will make that change in final rule AD action.

Conclusion

We reviewed the available data, including the comment received, and determined that air safety and the public interest require adopting the AD with the changes described previously. We determined that these changes will notincrease the economic burden on any operator or increase the scope of the AD.

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 10 products of U.S. registry. We also estimate that it will take about 4 work-hours per product to comply with the basic requirements of this AD. The average labor rate is $80 per work-hour.

Based on thesefigures, we estimate the cost of the AD on U.S. operators to be $3,200, or $320 per product.

In addition, we estimate that any necessary follow-on actions will take about 20 work-hours and require parts costing $20,000, for a cost of $21,600 per product. We have no way of determining the number of products that may need these actions.

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 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 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.

Weprepared 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 adding the following new AD: