AD 94-08-11 ACTIVE

This amendment adopts a new airworthiness directive (AD), applicable to certain Jetstream Model ATP airplanes, that requires replacement of certain circuit breakers on the left- and right-hand AC generator panel assemblies with new circuit breakers. This amendment is prompted by reports of failures due to localized overheating of the electric power circuit for the air conditioning recirculation fan in the environmental control system (ECS). The actions specified by this AD are intended to prevent the recirculation fan circuit from overheating, which could lead to smoke and/or flame in the fuselage.

Final rule

94-08-11 JETSTREAM AIRCRAFT LIMITED (FORMERLY BRITISH AEROSPACE): Amendment 39-8883. Docket 93-NM-166-AD.
Applicability: Model ATP airplanes, serial numbers 2002 through 2065 inclusive, certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent the recirculation fan circuit from overheating, which could lead to smoke and/or flame in the fuselage, accomplish the following:

(a) Within 600 hours time-in-service after the effective date of this AD, replace Texas Instrument circuit breakers 1HG3 and 2HG3 having part number (P/N) 6TC4-10, on the left- and right-hand AC generator panel assemblies at zones 131-05-00 and 132-05-00, respectively, with Genelco circuit breakers having P/N 4330-014-10, in accordance with Jetstream Service Bulletin ATP-21-24-10306A, dated July 30, 1993.

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

(c) Special flight permits may be issued in accordance with Federal Aviation Regulations (FAR) 21.197 and 21.199 to operate the airplane to a location where the requirements of this AD can be accomplished.

(d) The replacement shall be done in accordance with Jetstream Service Bulletin ATP-21-24-10306A, dated July 30, 1993. 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 Jetstream Aircraft, Inc., P.O. Box 16029, Dulles International Airport, Washington, DC 20041-6029. 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.

(e) This amendment becomes effective on June 6, 1994.

A proposal to amend part 39 of the Federal Aviation Regulations to include an airworthiness directive (AD) that is applicable to certain Jetstream Model ATP airplanes was published in the Federal Register on November 22, 1993 (58 FR 61635). That action proposed to require replacement of certain Texas Instrument circuit breakers on the left- and right-hand AC generator panel assemblies with certain Genelco circuit breakers.

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.

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.

The FAA estimates that 10 airplanes of U.S. registry will be affected by this AD, that it will take approximately 2 work hours per airplane to accomplish the required actions, and that the average labor rate is $55 per work hour. Required parts will cost approximately $225 per airplane. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $3,350, or $335 per airplane.

The total 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.

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 reasonsdiscussed 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 14 CFR part 39 of the Federal Aviation Regulations 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:

The service information referenced in this AD may be obtained from Jetstream Aircraft, Inc., P.O. Box 16029, Dulles International Airport, Washington, DC 20041-6029. This information may be examined at the Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

William Schroeder, Aerospace Engineer, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 227-2148; fax (206) 227-1320.