AD 97-03-12

This amendment adopts a new airworthiness directive (AD), applicable to certain Jetstream Model 4101 airplanes, that requires a one-time inspection for damage caused by arcing and overheating of the electrical ground posts ("earth posts") and ground cables for the direct current (DC) power generation and propeller de-icing systems of the left and right engines; and repair and replacement, if necessary. This amendment also requires the eventual replacement of earth posts with new posts. This amendment is prompted by reports indicating that earth posts on some airplanes have failed due to overheating. The actions specified by this AD are intended to prevent potential consequences of overheating, such as failure of the DC power generation and propeller de-icing systems.

Final rule

97-03-12 JETSTREAM AIRCRAFT LIMITED: Amendment 39-9917. Docket 96-NM-97-AD.

Applicability: Model 4101 airplanes having constructor number 41004 through 41074 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 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 overheating of the electrical ground posts ("earth posts") for the direct current (DC) power generation and de-icing systems of the left and right engines, which could result in such things as failure of these systems, accomplish the following:

(a) Within 300 hours time-in-service after the effective date of this AD, accomplish the actions specified in paragraphs (a)(1) and (a)(2) of this AD on both the left and right engines:

(1) Inspect each earth post and earth post bracket to detect damage caused by arcing, signs that it has been overheated, and lateral movement of the earth post, in accordance with Part A of Jetstream Service Bulletin J41-24-033, Revision 2, dated January 24, 1996. If any discrepancy is detected, prior to further flight, accomplish both paragraphs (a)(1)(i) and (a)(1)(ii) of this AD:

(i) Repair any damage and lateral movement in accordance with a method approved by the Manager, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate; and

(ii) Replace the earth post with a new earth post in accordance with Part B of the service bulletin.

(2) Inspect each ground cable ("earth cable") for the DC power generation and propeller de-icing systems to detect damage caused by arcing, and signs that the terminal tags and cable insulation have been overheated, in accordance with Part A of the service bulletin. If any discrepancy is detected, prior to further flight, replace the earth cable with a new or serviceable cable, in accordance with Part A of the service bulletin.

(b) Within 6 months after the effective date of this AD, replace each earth post with a new earth post, in accordance with Part B of Jetstream Service Bulletin J41-24-033, Revision 2, dated January 24, 1996. Any earth post that is replaced in accordance with paragraph (a)(1)(ii) of this AD need not be replaced again under the requirements of this paragraph.

(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, 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 actions shall be done in accordance with Jetstream Service Bulletin J41-24-033, Revision 2, dated January 24, 1996. 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.

(f) This amendment becomes effective on March 14, 1997.

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 Jetstream Model 4101 airplanes was published in the Federal Register on November 20, 1996 (61 FR 59038). That action proposed to require a one-time inspection to detect damage or signs of overheating of the earth posts and earth cables for the DC power generation and propeller de-icing systems of the left and right engines. That action proposed to require, prior to further flight, repair and replacement of damaged earth posts with new posts, and replacement of damaged earth cables with new or serviceable cables. That action also proposed to require the eventual replacement of all earth posts on all affected airplanes.

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 determinationof 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 44 Jetstream Model 4101 airplanes of U.S. registry will be affected by this proposed AD.

It will take approximately 8 work hours per airplane to accomplish the required inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the required inspection on U.S. operators is estimated to be $21,120, or $480 per airplane.

It will take approximately 8 work hours per airplane to accomplish the required replacement of earth posts, at an average labor rate of $60 per work hour. Required parts will be provided by the manufacturer at no charge. Based on these figures, the cost impact of the required replacement on U.S. operators is estimated to be $21,120, or $480 per airplane.

The cost impact figures discussed above are based on assumptions that nooperator 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:.