AD 98-20-06

This amendment adopts a new airworthiness directive (AD), applicable to certain Aerospatiale Model ATR42 series airplanes, that requires modification of the electrical power supply for the standby horizon indicator. 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 loss of the standby horizon indicator in the event of failure of emergency direct current (DC) power, which could result in reduced controllability of the airplane during instrument flight rules conditions.

Final rule.

98-20-06 AEROSPATIALE: Amendment 39-10772. Docket 98-NM-44-AD.

Applicability: Model ATR42-200, -300, and -320 series airplanes on which Aerospatiale Modification 4647 has not been accomplished; 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 (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 loss of the standby horizon indicator in the event of failure of emergency direct current (DC) power, which could result in reduced controllability of the airplane during instrument flight rules conditions, accomplish the following:

(a) Within 12 months after the effective date of this AD, modify the electrical power supply for the standby horizon indicator in accordance with Avions de Transport Regional Service Bulletin ATR42-34-0090, Revision 1, dated April 22, 1997.

(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 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.

(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.

(d) The actions shall be done in accordance with Avions de Transport Regional Service Bulletin ATR42-34-0090, Revision 1, dated April 22, 1997, which contains the following list of effective pages:

Page Number
Revision Level
Shown on Page
Date
Shown on Page
1-4, 15, 29-37,
1
April 22, 1997
49-52, 55-62, 69-72

5-14, 16-28,
Original
December 6, 1997
38-48, 52, 53,

63-68, 73, 74

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 96-230- 066(B), dated October 23, 1996.

(e) This amendment becomes effective on October 26, 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 series airplanes was published in the Federal Register on May 12, 1998 (63 FR 26106). That action proposed to require modification of the electrical power supply for the standby horizon indicator.
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, an operator of the affected airplanes, requests that the proposed rule be revised as follows:
For airplanes on which Aerospatiale Modification 03059 has not been accomplished, allow accomplishment of the actions specified in the original issue of Avions de Transport Regional Service Bulletin ATR42-34-0090.
For all other airplanes, Revision 1 of that service bulletin should be required to be accomplished.
The commenter notes that Revision 1 of the service bulletin is specified in the proposed rule as the appropriate source of service information for all affected airplanes. The commenter states that, from a technical standpoint, there is no difference between the original issue and Revision 1 of the service bulletin in regard to installations accomplished on its fleet. The commenter adds that Revision 1 integrates additional wiring options in Figures 9, 19, and 20 of the service bulletin (in regard to the commenter s fleet) for airplanes on which Aerospatiale Modification 03059 has been accomplished; that modification does not apply to the commenter s fleet.

The FAA does not concur with the commenter s request. The FAA has confirmed that some airplanes on which Aerospatiale Modification 03059 has not been accomplished that have been modified in accordance with the original issue of the service bulletin do not require additional work in accordance with Revision 1. However, other such airplanes do require additional work because of certain changes in the wiring design contained in Revision 1.

An operator of airplanes that have been modified previously in accordance with the original issue of the service bulletin should review the work specified in Revision 1 to determine what additional work is necessary for its affected fleet. If no additional work is necessary to conform to Revision 1 of the service bulletin, those airplanes would be considered to be in compliance with the AD, as provided by the phrase, "unless accomplished previously", in the compliance provision of the AD. No change to this final rule is necessary.

Conclusion
After careful review of the available data, including the comments 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 88 airplanes of U.S. registry will be affected by this AD, that it will take approximately 10 to 55 work hours per airplane to accomplish the required modification (depending on how many kits are needed for each airplane), 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 between $52,800 and $290,400, or between $600 and $3,300 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 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: