AD 99-23-06

This amendment adopts a new airworthiness directive (AD), applicable to all Aerospatiale Model SN-601 (Corvette) series airplanes, that requires repetitive inspections, and repair if necessary, of the locking indication system of the drag strut jack on the main landing gear (MLG) to detect corrosion and damage resulting from its operation. This proposal also requires replacement of seals and backup rings with new parts. 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 failure of the locking indication system of the drag strut jack on the MLG due to corrosion. Such corrosion could prevent the MLG from locking and result in the subsequent collapse of the MLG.

Final rule

99-23-06 AEROSPATIALE: Amendment 39-11402. Docket 98-NM-365-AD.

Applicability: All Model SN-601 (Corvette) series airplanes, certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been 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 (b) 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 failure of the locking indication system of the drag strut jack on the main landing gear (MLG) due to corrosion that could prevent the MLG from locking and result in the subsequent collapse of the MLG, accomplish the following:

(a) Within 3,600 flight hours or 36 months after the effective date of this AD, whichever occurs first, perform a detailed visual inspection to detect certain discrepancies of the locking indication system on the drag strut jack on the MLG, in accordance with Messier-Dowty Technical Instruction No. 20403, Issue 2, dated March 1998. Prior to reassembling the parts, replace all the seals and backup rings with new parts, in accordance with the Technical Instruction.

(1) If no corrosion is found on either plunger, prior to further flight, inspect for the free displacement of both plungers, in accordance with the Technical Instruction.

(i) If the displacement of both plungers is free without any hard points, repeat the inspection required by paragraph (a) of this AD thereafter at intervals not to exceed 72 months.

(ii) If the displacement of either plunger is not free, prior to further flight, replace the plunger with a new plunger, in accordance with the Technical Instruction. Repeat the inspection required by paragraph (a) of this AD thereafter at intervals not to exceed 72 months.

(2) If corrosion is found on either plunger, prior to further flight, replace the plunger with a new plunger, in accordance with the Technical Instruction. Repeat the inspection thereafter at intervals not to exceed 72 months.

(3) If no corrosion, marking, binding, or peening is found on any disassembled part removed from the stacking, other than the plungers, repeat the inspection thereafter at intervals not to exceed 72 months.

(4) If any corrosion, marking, binding or peening is found on any disassembled parts removed from the stacking, other than the plungers, prior to further flight, replace the part with a new part, in accordance with the Technical Instruction. Repeat the inspection thereafter at intervals not to exceed 72 months.

NOTE 2: For the purposes of this AD, a detailed visual inspection is defined as: "An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required."

Alternative Methods of Compliance
(b) 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, FAA, Transport Airplane Directorate. 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 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the International Branch, ANM-116.

Special Flight Permits
(c) Special flight permits may be issued in accordance 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.

Incorporation by Reference
(d) The actions shall be done in accordance with Messier-Dowty Technical Instruction No. 20403, Issue 2, dated March 1998. 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 4: The subject of this AD is addressed in French airworthiness directive 98-179-021(B), dated May 6, 1998.

(e) This amendment becomes effective on December 17, 1999.

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 all Aerospatiale Model SN-601 (Corvette) series airplanes was published in the Federal Register on September 10, 1999 (64 FR 49113). That action proposed to require repetitive inspections, and repair if necessary, of the locking indication system of the drag strut jack on the main landing gear (MLG) to detect corrosion and damage resulting from its operation. That action also proposal to require replacement of seals and backup rings with new parts.

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
TheFAA estimates that 2 airplanes of U.S. registry will be affected by this AD, that it will take approximately 8 work hours per airplane to accomplish the inspection, and that the average labor rate is $60 per work hour. The cost of required parts will be minimal. Based on these figures, the cost impact of this AD on U.S. operators is estimated to be $960, or $480 per airplane, 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: