AD 98-22-08

This amendment adopts a new airworthiness directive (AD), applicable to certain Aerospatiale Model SN 601 (Corvette) series airplanes, that requires repetitive inspections to detect discrepancies of the upper and lower reinforcement panels and panel fasteners of the wing roots; and corrective actions, if necessary. This amendment is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by this AD are intended to prevent debonding of the upper and lower reinforcement panels of the wing roots, which could result in reduced structural integrity of the wing.

Final rule

98-22-08 AEROSPATIALE: Amendment 39-10855. Docket 98-NM-161-AD.

Applicability: Model SN 601 (Corvette) series airplanes on which Aerospatiale Modification 1049 has been installed, certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (c) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent debonding of the upper and lower reinforcement panels of the wing roots, which could result in reduced structural integrity of the wing, accomplish the following:

(a) For airplanes that have been modified in accordance with Aerospatiale Corvette Service Bulletin 57-25, dated November 21, 1990: Within 8,300 flight cycles after installation of the modification, or within 100 flight cycles after the effective date of this AD, whichever occurs later, perform a sonic resonance inspection to detect debonding of the upper and lower reinforcement panels of the wing roots and a visual inspection to detect fatigue damage of the panel fasteners, in accordance with the Accomplishment Instructions of Aerospatiale Corvette Service Bulletin 57-24, Revision 1, dated May 30, 1994.

(1) If no panel debonding or fastener damage is found, repeat the sonic resonance inspection and the visual inspection thereafter at intervals not to exceed 1,000 flight cycles.

(2) If any panel debonding or fastener damage is found, prior to further flight, repair in accordance with a method approved by either the Manager, International Branch, ANM-116, or the Direction G n rale de l'Aviation Civile (DGAC), which is the airworthiness authority for France (or its delegated agent).

(b) For airplanes that have not been modified in accordance with Aerospatiale Corvette Service Bulletin 57-25, dated November 21, 1990: Prior to the accumulation of 8,200 total flight cycles, or within 100 flight cycles after the effective date of this AD, whichever occurs later, perform a sonic resonance inspection to detect debonding of the upper and lower reinforcement panels of the wing roots, and a visual inspection to detect fatigue damage of the panel fasteners, in accordance with the Accomplishment Instructions of Aerospatiale Corvette Service Bulletin 57-24, Revision 1, dated May 30, 1994.

(1) For any reinforcement panel on which no debonding or fastener damage is found, repeat the sonic resonance inspection and the visual inspection thereafter at intervals not to exceed 2,500 flight cycles or three years, whichever occurs first.

(2) For any reinforcement panel on which debonding is detected, and the total debonded area is less than or equal to 45% of the total area, and no contiguous debonded area on the panel is greater than 5% of the total area of the panel, repeat the sonic resonance inspection and the visual inspection thereafter at the interval specified in paragraph (b)(2)(i), (b)(2)(ii), or (b)(2)(iii), as applicable, of this AD.

(i) If the total debonded area on the panel is less than or equal to 10% of the total area, repeat the inspections of that panel thereafter at intervals not to exceed 2,500 flight cycles or 3 years, whichever occurs first.

(ii) If the total debonded area on the panel is greater than 10% and less than or equal to 30% of the total area, repeat the inspections of that panel thereafter at intervals not to exceed 2,000 flight cycles or 3 years, whichever occurs first.

(iii) If the total debonded area of the panel is greater than 30% and less than or equal to 45% of the total area, repeat the inspections of that panel thereafter at intervals not to exceed 1,000 flight cycles or 2 years, whichever occurs first.

(3) For any reinforcement panel on which debonding is detected, and the total debonded area of the panel is greater than 45% of the total area, or if any single debonded area on any single panel is greater than 5% of the total area of that panel, or if any panel fastener damage is detected, accomplish the actions specified in paragraphs (b)(3)(i) and (b)(3)(ii) of this AD.

(i) Prior to further flight, inspect the skin to determine the level of corrosion relative to the skin thickness in accordance with a method approved by either the Manager, International Branch, ANM-116, or the DGAC (or its delegated agent).

(A)If the depth of corrosion of the skin is less than or equal to 10% of the skin thickness, remove and replace the panel and treat the skin for corrosion, in accordance with the Accomplishment Instructions of Aerospatiale Corvette Service Bulletin 57-25, dated November 21, 1990.

(B) If the depth of corrosion of the skin exceeds 10% of the skin thickness, repair in accordance with a method approved by the Manager, International Branch, ANM-116, or in accordance with a method approved by the DGAC (or its delegated agent).

(ii) For airplanes on which the actions of paragraph (b)(3)(i)(A) of this AD have been accomplished: Within 8,300 flight cycles after accomplishment of paragraph (b)(3)(i)(A) of this AD, perform a sonic resonance inspection to detect debonding of the panel and a visual inspection to detect fatigue damage of the panel fasteners, in accordance with the Accomplishment Instructions of Aerospatiale Corvette Service Bulletin 57-24, Revision 1, dated May 30, 1994.

(A) If no debonding or fastener damage is found, repeat the inspection thereafter at intervals not to exceed 1,000 flight cycles.

(B) If any debonding or fastener damage is detected, prior to further flight, repair in accordance with a method approved by the Manager, International Branch, ANM-116, or in accordance with a method approved by the DGAC (or its delegated agent).

(c) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, International Branch, ANM-116. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, International Branch, ANM-116.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the International Branch, ANM-116.

(d) Special flight permits may be issued inaccordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

(e) Except as provided by paragraphs (a)(2), (b)(3)(i), (b)(3)(i)(B), and (b)(3)(ii)(B) of this AD, the actions shall be done in accordance with Aerospatiale Corvette Service Bulletin 57-25, dated November 21, 1990, and Aerospatiale Corvette Service Bulletin 57-24, Revision 1, dated May 30, 1994. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Aerospatiale, 316 Route de Bayonne, 31060 Toulouse, Cedex 03, France. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

NOTE 3: The subject of this AD is addressed in French airworthiness directive 91-045-010(B)R1, dated August 3, 1994.

(f) This amendment becomes effective on December 2, 1998.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain Aerospatiale Model SN 601 (Corvette) series airplanes was published in the Federal Register on August 27, 1998 (63 FR 45775). That action proposed to require repetitive inspections to detect discrepancies of the upper and lower reinforcement panels and panel fasteners of the wing roots; and corrective actions, if necessary.

Comments
Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were submitted in response to the proposal or the FAA's determination of the cost to the public.

Conclusion
The FAA has determined that air safety and the public interest require the adoption of the rule as proposed.

Cost Impact
The FAA estimates that 1 airplane of U.S. registry will be affected by this AD, that it will take approximately 2 work hours per airplane to accomplish the required inspection, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the inspection required by this AD on the single U.S. operator is estimated to be $120, per inspection cycle.

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted.

Regulatory Impact
The regulations adopted herein will not have substantial direct effects 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. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this action (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. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption"ADDRESSES."

List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (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 [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: