AD 96-25-13

This amendment adopts a new airworthiness directive (AD), applicable to certain Jetstream Model 4101 series airplanes, that requires a high frequency eddy current inspection to detect cracks of the boundary angle and joint angle of the rear pressure bulkhead, and repair, if necessary. This amendment also requires modification of the rear pressure bulkhead of the fuselage. This amendment is prompted by a report of fatigue cracking in the rear pressure bulkhead of the fuselage. The actions specified by this AD are intended to prevent such fatigue cracking, which could result in reduced structural integrity of the fuselage and, consequently, lead to the rapid decompression of the pressurized area of the airplane.

Final rule

96-25-13 JETSTREAM AIRCRAFT LIMITED: Amendment 39-9856. Docket 95-NM-271-AD.
Applicability: Model 4101 airplanes, constructors numbers 41004 through 41047 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 (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, unlessaccomplished previously.

To prevent fatigue-related cracking in the rear pressure bulkhead, which could result in reduced structural integrity of the fuselage and, consequently, lead to the rapid decompression of the pressurized area of the airplane, accomplish the following:

(a) Prior to the accumulation of 10,000 total landings, or within 6 months after the effective date of this AD, whichever occurs later, accomplish paragraphs (a)(1) and (a)(2) of this AD, in accordance with Jetstream Service Bulletin J41-53-020, Revision 1, dated June 4, 1996.

(1) Perform a high frequency eddy current inspection to detect cracks of the boundary angle and joint angle of the rear pressure bulkhead, in accordance with the service bulletin. 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.

(2) Modify the rear pressure bulkhead of the fuselage (Jetstream Modification JM41382A), in accordance with the service bulletin.

(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 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.

(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 inspection and modification shall be done in accordance with Jetstream Service Bulletin J41-53-020, Revision 1, dated June 4, 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.

(e) This amendment becomes effective on January 31, 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 as a supplemental notice of proposed rulemaking in the Federal Register on October 31, 1996 (61 FR 56169). That action proposed to require a high frequency eddy current inspection to detect cracks of the boundary angle and joint angle of the rear pressure bulkhead, and repair, if necessary. That action also proposed to require modification of the rear pressure bulkhead of the fuselage.

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.

Conclusion
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.

Cost Impact
The FAA estimates that 40 Model 4101 airplanes of U.S. registry will be affected by this AD, that it will take approximately 40 work hours per airplane to accomplish the required actions, and that the average labor rate is $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 AD on U.S. operators is estimated to be $96,000, or $2,400 per airplane.

The 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.

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: