AD 96-12-02

This amendment adopts a new airworthiness directive (AD), applicable to certain Airbus Model A300 B2 and B4 series airplanes, that requires measurements of the thickness of the inner skin of the longitudinal lap joint from the inside of the fuselage at certain stringers. This amendment also requires inspections to detect stress corrosion cracking in the subject area, and repair, if necessary. This amendment is prompted by reports of stress corrosion cracking found in the skin at the longitudinal lap joint at certain stringers of the fuselage, which was caused by the increased stress level in the subject area when it was reworked beyond certain limits. The actions specified by this AD are intended to prevent such stress corrosion cracking which, if not detected and corrected in a timely manner, could result in rapid depressurization of the airplane.

Final rule.

96-12-02 AIRBUS INDUSTRIE: Amendment 39-9644. Docket 95-NM-161-AD.

Applicability: Model A300 B2 and B4 series airplanes, manufacturer serial numbers 003 through 156 inclusive; on which Airbus Modification 2611 has not been installed; 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 (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.

NOTE 2: Model A300-600 series airplanes are not subject to the requirements of this AD.

Compliance: Required as indicated, unless accomplished previously.

To prevent stress corrosion cracking in the longitudinal lap joints of the fuselage, which could result in rapid depressurization of the airplane, accomplish the following:

NOTE 3: Any of the inspections and measurements required by this AD that were performed before the effective date of this AD in accordance with Airbus All Operator Telex (AOT) 53-05 (original issue), dated August 16, 1995, are considered acceptable for compliance with the applicable requirements of this AD.

(a) Within 60 days after the effective date of this AD, accomplish paragraphs (a)(1) and (a)(2) of this AD in accordance with Airbus All Operator Telex (AOT) 53-05, Revision 1, dated August 16, 1993.

(1) Measure the thickness of the inner skin of the longitudinal lap joint from the inside of the fuselage at stringer 57 between frames 65 and 72 using the ultrasonic thickness measurement method, in accordance with the AOT. If the thickness is less than or equal to the limits specified in the AOT, prior to further flight, repair the longitudinal lap joint in accordance with a method approved by the Manager, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate.

(2) Perform a high frequency eddy current (HFEC) inspection to detect cracking of the longitudinal lap joint at stringer 57 between frames 65 and 72, in accordance with the AOT. If any cracking is detected, prior to further flight, repair the longitudinal lap joint in accordance with a method approved by the Manager, Standardization Branch, ANM-113.

(b) Within 6 months after the effective date of this AD, accomplish paragraphs (b)(1) and (b)(2) of this AD in accordance with Airbus AOT 53-05, Revision 1, dated August 16, 1993.

(1) Measure the thickness of the inner skin of the longitudinal lap joint from the inside of thefuselage at stringer 52 (left- and right-hand) between frames 58 and 65 using the ultrasonic thickness measurement method, in accordance with the AOT. If the thickness is less than or equal to the limits specified in the AOT, prior to further flight, repair the longitudinal lap joint in accordance with a method approved by the Manager, Standardization Branch, ANM-113.

(2) Perform a HFEC inspection to detect cracking of the longitudinal lap joint at stringer 52 (left- and right-hand) between frames 58 and 65, in accordance with the AOT. If any cracking is detected, prior to further flight, repair the longitudinal lap joint in accordance with a method approved by the Manager, Standardization Branch, ANM-113.

(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. 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 4: 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 measurements and inspections shall be done in accordance with Airbus All Operator Telex (AOT) 53-05, Revision 1, dated August 16, 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 Airbus Industrie, 1 Rond Point Maurice Bellonte, 31707 Blagnac Cedex, France. 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 July 10, 1996.

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 Airbus Model A300 B2 and B4 series airplanes was published in the Federal Register on February 28, 1996 (61 FR 7444). That action proposed to require measurements of the thickness of the inner skin of the longitudinal lap joint from the inside of the fuselage at certain stringers using the ultrasonic thickness measurement method. That action also proposed to require high frequency eddy current (HFEC) inspections to detect cracking in the subject area, and repair, if necessary.
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the two comments received.

Support for the Proposal

Both commenters support the proposed rule.

Conclusion
After careful review of the available data, including the comments 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 17 airplanes of U.S. registry will be affected by this AD, that it will take approximately 32 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $32,640, or $1,920 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