AD 98-16-21

This amendment adopts a new airworthiness directive (AD), applicable to certain Aerospatiale Model ATR42 and ATR72 series airplanes, that requires one-time inspections to verify the correct shape of the stiffeners for the upper engine cowl and to detect wear of the aft upper fittings of the rear engine mounts, 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 wear (scratches or grooving) of the aft upper fittings of the rear engine mount, and consequent reduced structural integrity of the engine mounts.

Final rule

98-16-21 AEROSPATIALE: Amendment 39-10698. Docket 98-NM-146-AD.

Applicability: Model ATR42 and Model ATR72 series airplanes, as listed in Avions de Transport Regional Service Bulletins ATR42-54-0019 (for Model ATR42 series airplanes) and ATR72-54-1011 (for Model ATR72 series airplanes), both dated March 9, 1998; 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 (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 conditionhas not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent wear (scratches or grooving) of the aft upper fittings of the rear engine mount, and consequent reduced structural integrity of the engine mounts, accomplish the following:

(a) Within 10 months after the effective date of this AD, perform a one-time visual inspection of the stiffeners for the upper left and right engine cowls to ensure the stiffeners have the correct lower edge profile, in accordance with the Accomplishment Instructions of Avions de Transport Regional Service Bulletin ATR42-54-0019 or ATR72-54-1011, both dated March 9, 1998, as applicable.

(1) If the lower edge profile of the stiffener meets the specifications of the applicable service bulletin, no further action is required by this paragraph.

(2) If the lower edge profile of the stiffener does not meet the specificationsof the applicable service bulletin, prior to further flight, modify or replace the stiffener with a new stiffener in accordance with the applicable service bulletin.

(b) Within 10 months after the effective date of this AD, perform a one-time detailed visual inspection for wear (scratches or grooving) of the aft upper fittings of the left- and right-hand rear engine mounts, in accordance with Avions de Transport Regional Service Bulletin ATR42-54-0019 (for Model ATR42 series airplanes) or ATR72-54-1011 (for Model ATR72 series airplanes), both dated March 9, 1998, as applicable.

(1) If no wear is detected, no further action is required by this paragraph.

(2) If any wear is detected that cannot be removed with a Type I or II blend-out as described in the applicable service bulletin, prior to further flight, repair in accordance with a method approved by the Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate.

(3) If any wear other than thatspecified in paragraph (b)(2) of this AD is detected, prior to further flight, repair in accordance with the Accomplishment Instructions of the applicable service bulletin.

(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 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) Except as provided by paragraph (b)(2) of this AD, the actions shall be done in accordance with Avions de Transport Regional Service Bulletin ATR42-54-0019, dated March 9, 1998, or Avions de Transport Regional Service Bulletin ATR72-54-1011, dated March 9, 1998, as applicable. 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 directives 98-069- 073(B) (for Model ATR42 series airplanes), dated February 11, 1998; and 98-071-035(B) (for Model ATR72 series airplanes), dated February 11, 1998, as revised by Erratum 98-071-35(B), dated February 25, 1998.

(f) This amendment becomes effective on September 11, 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 ATR42 and ATR72 series airplanes was published in the Federal Register on June 12, 1998 (63 FR 32152). That action proposed to require one-time inspections to verify the correct shape of the stiffeners for the upper engine cowl and to detect wear of the aft upper fittings of the rear engine mounts, 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 152 airplanes of U.S. registry will be affected by this AD, that it will take approximately 15 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $136,800, or $900 per airplane.

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 forpart 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: