AD 98-09-04

This amendment adopts a new airworthiness directive (AD), applicable to certain Aerospatiale Model ATR72 series airplanes, that requires a one-time high frequency eddy current inspection to detect cracking of the lower fuselage structure, and repair, if necessary. This amendment also requires modification of certain fastener holes in the lower fuselage structure. 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 reduced structural integrity of the airplane due to fatigue cracking in the lower fuselage structure.

Final rule.

98-09-04 AEROSPATIALE: Amendment 39-10483. Docket 97-NM-263-AD.

Applicability: Model ATR72 series airplanes on which Aerospatiale Modification 2879 or Modification 2628 has not been incorporated, 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 reduced structural integrity of the airplane due to fatigue cracking in the lower fuselage structure, accomplish the following:

(a) Prior to the accumulation of 17,500 total flight cycles, or within 500 flight cycles after the effective date of this AD, whichever occurs later: Except as provided in paragraph (b) of this AD, perform a one-time high frequency eddy current inspection to detect fatigue cracking around the fastener holes in the lower fuselage structure in the area of the side brace fitting near frame 25 on the left- and right-hand sides, and modify crack-free fastener holes, as required by paragraph (a)(1) and/or (a)(2) of this AD, as applicable.

(1) For airplanes on which Aerospatiale Modification 2879 has not been installed: Perform the inspection and modification in accordance with Aerospatiale Service Bulletin ATR72-53-1022, Revision 2, dated February 20, 1995.

(2) For airplaneson which Aerospatiale Modification 2628 has not been installed: Perform the inspection and modifications in accordance with Aerospatiale Service Bulletins ATR72-53-1034, Revision 1, and ATR72-53-1053, Revision 1, both dated March 28, 1995.

(b) If any crack or oversize hole is found during the accomplishment of paragraph (a) of this AD, and if any service bulletin listed in paragraph (a) of this AD specifies to contact the manufacturer for an appropriate corrective action: Prior to further flight, repair the discrepancy in accordance with a method approved by the Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate.

(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) The actions shall be done in accordance with the following Aerospatiale service bulletins, which contain the following list of effective pages:

Service Bulletin
Referenced and Date
Page Number
Shown on Page
Revision Level
Shown on Page
Date
Shown on Page
ATR72-53-1034,
Revision 1
March 28, 1995
1, 7, 9, 11-17, 20,
21, 23-25, 29, 30

2-6, 8, 10, 18, 19,
22, 26-28
1

Original
March 28, 1995

November 4, 1994
ATR72-53-1022,
Revision 2
February 20, 1995
1, 11, 12, 16

2

3-10, 13-15, 17-24
2

1

Original
February 20, 1995

November 10, 1994

July 29, 1994
ATR72-53-1053,
Revision 1
March 28, 1995
1, 6-8, 16, 19

2-5, 9-15, 17, 18, 20
1

Original
March 28, 1995

November 7, 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 94-191-022(B), dated August 17, 1994.

(f) This amendment becomes effective on May 29, 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 ATR72 series airplanes was published in the Federal Register on February 5, 1998 (63 FR 5900). That action proposed to require a one-time high frequency eddy current inspection to detect cracking of the lower fuselage structure, and repair, if necessary. That action also proposed to require modification of certain fastener holes in the lower fuselage structure.

Comments
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the single comment received.

The commenter supports the proposed rule.

Conclusion
After careful review of the available data, including the comment noted above, 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 7 airplanes of U.S. registry will be affected by this AD.

Accomplishment of the actions specified in Aerospatiale Service Bulletin ATR72-53-1022 will take approximately 80 work hours per airplane, at an average labor rate of $60 per work hour. Required parts will be provided by the manufacturer at no cost to the operators. Based on these figures, the cost impact on U.S. operators of the actions specified in this service bulletin and required by this AD is estimated to be $4,800 per airplane.

Accomplishment of the actions specified in Aerospatiale Service Bulletin ATR72-53-1034 will take approximately 65 work hours per airplane, at an average labor rate of $60 per work hour. Required parts will be provided by the manufacturer at no cost to the operators. Based on these figures, the cost impact on U.S. operators of the actions specified in this service bulletin and required by this AD is estimated to be $3,900 per airplane.

Accomplishmentof the actions specified in Aerospatiale Service Bulletin ATR72-53-1053 will take approximately 65 work hours per airplane, at an average labor rate of $60 per work hour. Required parts will be provided by the manufacturer at no cost to the operators. Based on these figures, the cost impact on U.S. operators of the actions specified in this service bulletin and required by this AD is estimated to be $3,900 per airplane.

The cost impact figures discussed above are 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 isdetermined 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: