AD 97-10-09

This amendment adopts a new airworthiness directive (AD), applicable to certain Jetstream Model 4101 airplanes, that requires repetitive detailed visual inspections to detect cracks on frame 179 at the attachment bracket for the door restraint cable, and various follow-on actions. This amendment also requires installation of new doublers and stress pads on frame 179, which would terminate the repetitive inspections. This amendment is prompted by reports of cracks in frame 179 of the fuselage at the attachment bracket for the door restraint cable on in-service airplanes due to improper rigging of the door restraint system. The actions specified by this AD are intended to prevent such cracking, which could result in structural failure of the fuselage and consequent rapid decompression of the pressurized section of the fuselage.

Final rule

97-10-09 JETSTREAM AIRCRAFT LIMITED: Amendment 39-10021. Docket 96-NM-168-AD.
Applicability: Model 4101 airplanes, constructors numbers 41004 through 41086 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 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 (d) 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 cracking in frame 179 of the fuselage, which could result in structural failure of the fuselage and consequent rapid decompression of the pressurized section of the fuselage, accomplish the following:

(a) Prior to the accumulation of 3,000 total flight cycles, or within 300 flight cycles after the effective date of this AD, whichever occurs later, perform a detailed visual inspection to detect cracks on frame 179 at the attachment bracket for the door restraint cable, in accordance with Part 1 of the Accomplishment Instructions of Jetstream Alert Service Bulletin J41-A53-024, dated April 26, 1996.

(1) If no crack is detected, repeat the visual inspection thereafter at intervals not to exceed 1,000 flight cycles. After each inspection, perform the actions specified in paragraph (c) of this AD.

(2) If any crack is detected, prior to further flight, repair it in accordance with a method approved by the Manager, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate. After repair, perform the actions specified in paragraph (c) of this AD.

(b) Within 24 months after the effective date of this AD, perform the visual inspection specified in paragraph (a) of this AD in accordance with Part 2 of the Accomplishment Instructions of Jetstream Alert Service Bulletin J41-A53-024, dated April 26, 1996; and accomplish the applicable follow-on actions specified in paragraph (b)(1) or (b)(2) of this AD.

(1) If no crack is detected, prior to further flight, install new doublers and stress pads on frame 179 in accordance with the alert service bulletin. Immediately after installation, perform the actions specified in paragraph (c) of this AD. Accomplishment of these actions constitutes terminating action for the repetitive inspection requirements of paragraph (a)(1) of this AD.

(2) If any crack is detected, prior to further flight, repair it in accordance with a method approved by the Manager, Standardization Branch, ANM-113. Prior to further flight following accomplishment of the repair, install new doublers and stress pads on frame 179 in accordance with the alert service bulletin; and then perform the actions specified in paragraph (c) of this AD. Accomplishment of these actions constitutes terminating action for the repetitive inspection requirements of paragraph (a)(1) of this AD.

(c) Prior to further flight following accomplishment of the actions as specified in paragraph (a)(1), (a)(2), (b)(1), or (b)(2) of this AD, perform a test to verify proper adjustment of the restraint cable, in accordance with Jetstream Alert Service Bulletin J41-A53-024, dated April 26, 1996. If the restraint cable has been improperly adjusted, prior to further flight, correct the discrepancy in accordance with the alert service bulletin.

(d) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved bythe Manager, Standardization Branch, ANM-113. 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.

(e) 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.

(f) Certain actions shall be done in accordance with Jetstream Alert Service Bulletin J41-A53-024, dated April 26, 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, DullesInternational 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.

(g) This amendment becomes effective on June 16, 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 February 14, 1997 (62 FR 6888). That action proposed to require repetitive detailed visual inspections to detect cracks on frame 179 at the attachment bracket for the door restraint cable, and various follow-on actions. That action also proposed to require installation of new doublers and stress pads on frame 179, which would constitute terminating action for the repetitive inspection requirements.

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 49 Jetstream Model 4101 airplanes of U.S. registry will be affected by this AD.

The required inspection will take approximately 2 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the inspection required by this AD on U.S. operators is estimated to be $5,880, or $120 per airplane, per inspection cycle.

The required installation will take approximately 8 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts will be supplied by the manufacturer at no cost to the operators. Based on these figures, the cost impact of the installation required by this AD on U.S. operators is estimated to be $23,520, or $480 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: