AD 2007-15-09

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 in the upper wing strut fittings of some PC-6 aircraft.
It is possible that the spherical bearing of the wing strut fittings installed in the underwing can be loose in the fitting or cannot rotate because of corrosion. In this condition, the joint cannot function as designed and fatigue cracks may then develop. Undetected cracks in this area could lead to failure of the upper attachment fitting. This could result in the failure of the wing structure with subsequent loss of control of the airplane.

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

Final Rule.

2007-15-09 Pilatus Aircraft Limited: Amendment 39-15138; Docket No. FAA-2007-28157; Directorate Identifier 2007-CE-046-AD.

Effective Date

(a) This airworthiness directive (AD) becomes effective September 4, 2007.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Models PC-6, PC-6-H1, PC-6-H2, PC-6/350, PC-6/350-H1, PC-6/350-H2, PC-6/A, PC-6/A-H1, PC-6/A-H2, PC-6/B-H2, PC-6/B1-H2, PC-6/B2-H2, PC-6/B2-H4, PC-6/C-H2, and PC-6/C1-H2 airplanes; manufacturer serial numbers (MSN) 101 through 951, and MSN 2001 through 2092; that are certificated in any category. These airplanes are also identified as Fairchild Republic Company PC-6 airplanes, Fairchild Industries PC-6 airplanes, Fairchild Heli Porter PC-6 airplanes, or Fairchild-Hiller Corporation PC-6 airplanes.

Subject

(d) Air Transport Association of America (ATA) Code 57: Wings.

Reason

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

This Airworthiness Directive (AD) is prompted due to the discovery of cracks in the upper wing strut fittings of some PC-6 aircraft.

It is possible that the spherical bearing of the wing strut fittings installed in the underwing can be loose in the fitting or cannot rotate because of corrosion. In this condition, the joint cannot function as designed and fatigue cracks may then develop. Undetected cracks in this area could lead to failure of the upper attachment fitting. This could result in the failure of the wing structure with subsequent loss of control of the airplane.

In order to correct and monitor this situation, the present AD mandates a one time inspection of the wing strut fittings and replacement of damaged wing strut fittings with new ones. This AD also requires examination of the spherical bearings installed in the wing strut fittings and their replacement for bearings that do not pass the examination criteria.

Actions and Compliance

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

(1) For MSN 2001 through MSN 2092: Within the next 100 hours time-in-service (TIS) on the upper wing strut fitting after September 4, 2007 (the effective date of this AD) or within 3 months after September 4, 2007 (the effective date of this AD), whichever occurs first, and repetitively thereafter at intervals not to exceed 12 months, do the actions specified in paragraph (f)(3) of this AD.

(2) For MSN 101 through MSN 951 do the following actions, as applicable:

(i) If the upper wing strut fitting has less than 3,500 hours TIS or has been installed for less than 84 months (7 years): Within the next 1,000 hours TIS on the upper wing strut fitting after September 4, 2007 (the effective date of this AD) or within 24 months after September 4, 2007 (the effective date of this AD) without exceeding 3,600 hours TIS or 87 months (7 years, 3 months), whichever occurs first, and repetitively thereafter at intervals not to exceed 12 months, do the actions specified in paragraph (f)(3) of this AD, or;

(ii) If the upper wing strut fitting has 3,500 or more hours TIS or has been installed for 84 months (7 years) or longer: Within the next 100 hours TIS on the upper wing strut fitting after September 4, 2007 (the effective date of this AD) or within 3 months after September 4, 2007 (the effective date of this AD), whichever occurs first, and repetitively thereafter at intervals not to exceed 12 months, do the actions specified in paragraph (f)(3) of this AD.

Note 1: If the TIS of the upper wing strut fittings cannot be positively determined by a review in the airplane maintenance records, then by default the upper wing strut fittings were installed from the date of original Certificate of Airworthiness.

(3) Do the following at the times specified in paragraph (f)(1) or (f)(2) of this AD:

(i) Perform a visual and non-destructive inspection of the upper wing strut fittings for cracks following the Accomplishment Instructions in Pilatus Aircraft Ltd. Service Bulletin No. 57-004, dated April 16, 2007.

(ii) Examine for conformity the spherical bearings following the Accomplishment Instructions in Pilatus Aircraft Ltd. Service Bulletin No. 57-004, dated April 16, 2007.

(4) If during any inspection required by paragraph (f)(3)(i) of this AD cracks are found in the upper wing strut fitting, before further flight replace the wing strut fitting with a new part number (P/N) 111.35.06.185 (left side) or P/N 111.35.06.186 (right side) following the Accomplishment Instructions in Pilatus Aircraft Ltd. Service Bulletin No. 57-004, dated April 16, 2007. Replacement of the upper wing strut fitting does not terminate the repetitive inspection specified in paragraph (f)(3) of this AD.

(5) If during any inspection required by paragraph (f)(3)(ii) of this AD the spherical bearing is found not in conformity, before further flight replace the bearing with a new P/N 944.61.00.109 following the Accomplishment Instructions in Pilatus Aircraft Ltd. Service Bulletin No. 57-004, dated April 16, 2007. Replacement of the spherical bearing does not terminate the repetitive inspection specified in paragraph (f)(3) of this AD.

(6) Report to Pilatus Aircraft Ltd. Customer Liason Manager results of the inspection/examination using Table 1 of Pilatus Aircraft Ltd. Service Bulletin No. 57-004, dated April 16, 2007.

FAA AD Differences

Note 2: This AD differs from the MCAI and/or service information as follows:

(1) The FAA AD is requiring repetitive inspections and reporting results to the manufacturer, not just a one-time inspection and report as required in the MCAI.

(2) The Service Bulletin specifies "subsequent inspections for cracks will be included in Chapter 5 of the Aircraft Maintenance Manual (AMM).'' The only way we (FAA) can mandate these repetitive inspections is through an AD.

Other FAA AD Provisions

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

(1) Alternative Methodsof Compliance (AMOCs): The Manager, Standards Staff, 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. 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 reportingrequirement 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 European Aviation Safety Agency (EASA) AD No: 2007-0114, dated May 02, 2007; and Pilatus Aircraft Ltd. Service Bulletin No. 57-004, dated April 16, 2007, for related information.

Material Incorporated by Reference

(i) You must use Pilatus Aircraft Ltd. Service Bulletin No. 57- 004, dated April 16, 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 Pilatus Aircraft Ltd., Customer Liaison Manager, CH-6371 STANS, Switzerland; telephone: +41 (0)41 6196580; fax: +41 (0)41 619 6576; e-mail: fodermatt@pilatus-aircaft.com.

(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/cfr/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 May 30, 2007 (72 FR 29895). 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 in the upper wing strut fittings of some PC-6 aircraft.
It is possible that the spherical bearing of the wing strut fittings installed in the underwing can be loose in the fitting or cannot rotate because of corrosion. In this condition, the joint cannot function as designed and fatigue cracks may then develop. Undetected cracks in this area could lead to failure of upper the attachment fitting. This could result in the failure of the wing structure with subsequent loss of control of the airplane.
In order to correct and monitor this situation, the present AD mandates a one time inspection of the wing strut fittings and replacement of damaged wing strut fittings with new ones. This AD also requires examination of the spherical bearings installed in the wing strut fittings and their replacement for bearings that do not pass the examination criteria.

Comments

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

Comment Issue: Allow a Dye-Penetrant Inspection

One commenter requested that we allow a dye-penetrant inspection as an option to the eddy current inspection.
Without specific procedures and proposed intervals, the FAA is not able to approve dye-penetrant inspection as an approved method for this AD. The European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community and Pilatus (the design organization approval holder) only approved using an eddy current procedure for this inspection. Pilatus has only established procedures to detect cracks in the affected areas using the eddy current method. The FAA will not change the AD to allow for dye- penetrant inspections in place of eddy current as called out for in the NPRM per the Pilatus service bulletin (SB) without having specific procedures and intervals that we can coordinate with EASA and Pilatus. An operator may propose these procedures and intervals to the FAA using the alternative method of compliance (AMOC) process specified in 14 CFR 39.19 and the AD. The AMOC proposal must provide the complete method of inspection that the operator believes will provide an acceptable level of safety as that proposed in the AD. The FAA will then coordinate the proposed AMOC with Pilatus and EASA to determine if the method provides an acceptable level of safety. If so, an AMOC can be granted for the FAA issued AD.

We are making no changes to the final rule AD action based on this comment.

Conclusion

We reviewed the availabledata, including the comment received, 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 50 products of U.S. registry. We also estimate that it will take about 7 work-hours per product to comply with basic requirements of this AD. The average labor rate is $80 per work-hour. Based on these figures, we estimate the cost of this AD to the U.S. operators to be $28,000 or $560 per product.

In addition, we estimate that any necessary follow-on actions would take about 15 work-hours and require parts costing $2,500, for a cost of $3,700 per fitting or $7,400 per product if both fittings are replaced. 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.

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://dms.dot.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: