AD 95-15-03

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Aerospatiale Model ATR42 series airplanes. This action requires replacement of the currently installed side brace pins of the main landing gear (MLG) with new pins. This amendment is prompted by a report of a ruptured pin on an in-service airplane. The actions specified in this AD are intended to prevent failure of the side brace pins and the subsequent collapse of the MLG.

Final rule; request for comments.

95-15-03 AEROSPATIALE: Amendment 39-9306. Docket 95-NM-100-AD.

Applicability: Model ATR42 series airplanes having manufacturer's serial numbers 121 through 125 inclusive, 128 through 139 inclusive, and 141 through 143 inclusive, 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 use the authority provided in paragraph (c) to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition; or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration onthe unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any airplane from the applicability of this AD.

Compliance: Required as indicated, unless accomplished previously.

To prevent failure of the side brace pins and the subsequent collapse of the main landing gear (MLG), accomplish the following:

(a) Prior to the accumulation of 6,000 total flight cycles on the MLG pins or within 250 flight cycles after the effective date of this AD, whichever occurs later, replace the currently installed side brace pins of the MLG with new side brace pins having part number (P/N) S5357841320600, in accordance with Avions de Transport Regional Service Bulletin ATR42-32- 0070, dated April 3, 1995.

(b) As of the effective date of this AD, only side brace pins of the MLG having P/N S5357841320600 shall be installed on any airplane.

(c) An alternative method of compliance or adjustment of the compliance time thatprovides an acceptable level of safety may be used if approved by the Manager, Standardization Branch, ANM-113, 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, Standardization Branch, ANM-113.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Standardization Branch, ANM-113.

(d) 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.

(e) The replacement shall be done in accordance with Avions de Transport Regional Service Bulletin ATR42-32-0070, dated April 3, 1995. This incorporation by reference was approved by the Director of the Federal Register in accordancewith 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.

(f) This amendment becomes effective on August 8, 1995.

The Direction G n rale de l'Aviation Civile (DGAC), which is the airworthiness authority for France, recently notified the FAA that an unsafe condition may exist on certain Aerospatiale Model ATR42 series airplanes. The DGAC advises that it has received a report indicating that the side brace pin of the main landing gear (MLG) ruptured on an in-service airplane. Investigation revealed that the cause of the ruptured pin may be attributed to a defect in the manufacturing process. The defective pins were improperly dehydrogenated after they were chromium plated. This condition, if not corrected, could result in failure of the side brace pins and the subsequent collapse of the MLG.

The defective pins have been isolated and identified as those installed on airplanes having manufacturer's serial numbers 121 through 125 inclusive, 128 through 139 inclusive, and 141 through 143 inclusive.

Avions de Transport Regional has issued Service Bulletin ATR42-32-0070, dated April 3, 1995, which describes procedures for replacement of the currently installed side brace pins of the MLG with new pins having part number (P/N) S5357841320600. These replacement pins are not susceptible to the rupture problems associated with the currently installed pins. The French DGAC classified this service bulletin as mandatory and issued French airworthiness directive 95-051-058(B), dated March 15, 1995, in order to assure the continued airworthiness of these airplanes in France.

This airplane model is manufactured in France and is type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, the French DGAC has kept the FAA informed of the situation described above. The FAA has examined the findings of the French DGAC, reviewed all available information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.

Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design registered in the United States, this AD is being issued to prevent failure of the side brace pins of the MLG. This AD requires replacement of the currently installed side brace pins of the MLG with new pins. The actions are required to be accomplished in accordance with the service bulletin described previously.

As a result of recent communications with the Air Transport Association (ATA) of America, the FAA has learned that, in general, some operators may misunderstand the legal effect of AD's on airplanes that are identified in the applicability provision of the AD, but that have been altered or repaired in the area addressed by the AD. The FAA points out that all airplanes identified in the applicability provision of an AD are legallysubject to the AD. If an airplane has been altered or repaired in the affected area in such a way as to affect compliance with the AD, the owner or operator is required to obtain FAA approval for an alternative method of compliance with the AD, in accordance with the paragraph of each AD that provides for such approvals. A note has been included in this rule to clarify this long-standing requirement.

Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

Comments Invited
Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 95-NM-100-AD." The postcard will be date stamped and returned to the commenter.

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.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.
39.13 - [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: