AD 97-03-08

This amendment adopts a new airworthiness directive (AD), applicable to certain Jetstream Model 4101 airplanes, that requires repetitive inspections to detect cracking of the offset lightening hole on the drag brace of the left and right main landing gear (MLG); and replacement of these braces with braces having a centralized lightening hole. This replacement terminates the repetitive inspections. This amendment is prompted by a report indicating that fatigue cracking was detected on the upper link of a drag brace. The actions specified by this AD are intended to prevent fatigue cracking of the drag braces of the MLG, which, if not corrected, could cause the MLG to fail and, consequently, result in reduced controllability of the airplane during takeoff, landing, and taxiing.

Final rule

97-03-08 JETSTREAM AIRCRAFT LIMITED: Amendment 39-9914. Docket 96-NM-86-AD.
Applicability: Model 4101 airplanes having constructors numbers 41004 through 41009 inclusive, and 41017; equipped with a main landing gear (MLG) on which drag braces having Jetstream part numbers (P/N) AIR84352-0 through AIR84352-4, inclusive, and having offset lightening holes, are installed; certificated in any category.

NOTE 1: Drag braces having Jetstream part numbers (P/N) AIR84352-0 through AIR84352-4 inclusive, can have either offset or centralized lightening holes. This AD applies only to those airplanes equipped with those drag braces that have the offset lightening holes.

NOTE 2: 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 therequirements 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 fatigue cracking of the drag brace of the left and right MLG which, if not corrected, could cause the MLG to fail and, consequently, lead to reduced controllability of the airplane during takeoff, landing, and taxiing, accomplish the following:

(a) Within 50 hours time-in-service after the effective date of this AD, perform a detailed visual inspection to detect cracking at the offset lightening hole on the drag brace of the left and right MLG, in accordance with Part 1 of Jetstream Service Bulletin J41-32-049, Revision 1, dated January 15, 1996.

NOTE 3: Accomplishment of the visual inspection in accordance with Part 1 of Jetstream Service Bulletin J41-32-049, dated November 21, 1995, is considered acceptable for compliance with this paragraph.

(1) If no cracking is detected, repeat this inspection thereafter at intervals not to exceed 50 hours time-in-service until the requirements of paragraph (b) of this AD have been accomplished.

(2) If any cracking is detected, prior to further flight, replace the drag brace with a drag brace that has Jetstream part number (P/N) AIR84352-4 and a centralized lightening hole, in accordance with Part 2 of Jetstream Service Bulletin J41-32-049, Revision 1, dated January 15, 1996. This replacement constitutes terminating action for the repetitive inspections and replacement of that brace required by paragraphs (a) and (b), respectively, of this AD.

NOTE 4: Accomplishment of the replacement inaccordance with Part 2 of Jetstream Service Bulletin J41-32-049, dated November 21, 1995, is considered acceptable for compliance with paragraphs (a)(2) and (b) of this AD.

(b) Within two years after the effective date of this AD, replace any MLG drag brace that has P/N AIR84352-0 through AIR84352-4, inclusive, and an offset lightening hole, with a drag brace that has Jetstream P/N AIR84352-4 and a centralized lightening hole, in accordance with Part 2 of Jetstream Service Bulletin J41-32-049, Revision 1, dated January 15, 1996. This replacement constitutes terminating action for the repetitive inspections required by paragraph (a) of this AD.

(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 5: 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 inspections and replacements shall be done in accordance with Jetstream Service Bulletin J41-32-049, Revision 1, dated January 15, 1996, which contains the following list of effective pages:

Page Number
Revision Level
Shown on Page
Date
Shown on Page
1, 3
1
January 15, 1996
2, 4-9
Original
November 21, 1995

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 11, 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 12, 1996 (61 FR 58016). That action proposed to require repetitive detailed visual inspections of the offset lightening hole on the drag brace of the left and right MLG to detect cracking. That action also proposed to require, prior to further flight, the replacement of any cracked brace with a brace having a centralized lightening hole. Such replacement would constitute terminating action for the repetitive detailed visual inspections.

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 1 Jetstream Model 4101 airplane of U.S. registry will be affected by this AD.

It will take approximately 1 work hour 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 the single U.S. operator is estimated to be $60 per inspection cycle.

It will take approximately 2 work hours per airplane to accomplish the required replacement, at an average labor rate of $60 per work hour. Required parts will be provided by the manufacturer at no cost to the operator. Based on these figures, the cost impact of the required replacement on the single U.S. operator is estimated to be $120.

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 actionsin 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: