AD 97-07-02

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Airbus Model A300 series airplanes. It requires a one-time template inspection of the rear pressure bulkhead to detect dents; repetitive eddy current inspections of dents greater than a certain depth to detect cracking; and repair, if necessary. This amendment is prompted by a report indicating that cracking has been found in the vicinity of a dent in the rear pressure bulkhead of one airplane. The actions specified by this amendment are intended to prevent fatigue cracking resulting from a dent in the rear pressure bulkhead; that condition, if not corrected, could reduce the structural integrity of the bulkhead and, consequently, lead to rapid depressurization of the airplane.

Final rule.

97-07-02 AIRBUS INDUSTRIE: Amendment 39-9975. Docket 96-NM-107-AD.

Applicability: Model A300 airplanes having serial numbers 001 through 0156, 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 (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 fatigue cracking of the rear pressure bulkhead, which could reduce its structural integrity, and consequently lead to rapid depressurization of the airplane, accomplish the following:

(a) Within 12 months after the effective date of this AD, perform a template inspection to detect dents of the rear pressure bulkhead in the area between right hand and left hand radial stiffeners RS 5 and RS 13, in accordance with Airbus Service Bulletin A300-53-302, dated November 3, 1995.

(b) If no dent, or if no dent that is greater than 2 mm in depth, is detected during the template inspection required by paragraph (a) of this AD: No further action is required by this AD.

(c) If any dent that is greater than 2 mm in depth is detected during the template inspection required by paragraph (a) of this AD: Prior to further flight, inspect the dent for cracking, in accordance with Airbus Service Bulletin A300-53-302, dated November 3, 1995.

(1) If no crack isdetected: Repeat the inspection for cracking at intervals not to exceed 2,000 landings until the permanent repair specified in paragraph (c)(1)(i) of this AD is accomplished.

(i) Prior to the accumulation of 5 years or 11,000 landings after the effective date of this AD, whichever occurs first, accomplish the permanent repair of the dent in accordance with paragraph 2.B.(3)(c)1 of the Accomplishment Instructions of the service bulletin.

(ii) Accomplishment of the permanent repair of the dent constitutes terminating action for the repetitive inspection requirements of this paragraph, and thereafter, no further action is required.

(2) If only radial cracking is detected in the circumferential strap and no other cracking is found elsewhere in the rear pressure bulkhead: Prior to further flight, accomplish the circumferential strap repair, in accordance with paragraph 2.B.(3)(c)2 of the Accomplishment Instructions of the service bulletin. Thereafter, inspect the dent for cracking at intervals not to exceed every 1,000 landings until the permanent repair specified in paragraph (c)(2)(i) of this AD is accomplished.

(i) Prior to the accumulation of 5 years or 11,000 landings after the effective date of this AD, whichever occurs first, accomplish permanent repair of the dent in accordance with the paragraph 2.B.(3)(c)2 of the Accomplishment Instructions of the service bulletin.

(ii) Accomplishment of the permanent repair of the dent constitutes terminating action for the repetitive inspection and repair requirements of this paragraph and thereafter, no further action is required.

(3) If any other cracking not specified in paragraph (c)(1) or (c)(2) of this AD is detected: Prior to further flight, accomplish a permanent repair of the dent in accordance with the paragraph 2.B.(3)(c)3 or 4, as applicable, of the Accomplishment Instructions of the service bulletin; or in a manner approved by the Manager, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate. Accomplishment of the permanent repair of the dent in accordance with the Accomplishment Instructions of the service bulletin constitutes terminating action for the requirements of this AD and, thereafter, no further action is required.

(d) 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.

(e) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

(f) The actions shall be done in accordance with Airbus Service Bulletin A300-53- 302, dated November 3, 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 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.

(g) This amendment becomes effective on May 2, 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 Airbus Model A300 series airplanes was published in the Federal Register on November 5, 1996 (61 FR 56923). That action proposed to require a one-time template inspection of the rear pressure bulkhead to detect dents; repetitive eddy current inspections of dented areas greater than a certain depth to detect fatigue cracking; 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 comments received.

Support for the Proposal
One commenter supports the proposed AD.

Request to Explain Adequacy of One-Time Inspection
One commenter asks if a one-time inspection, as would be required by the AD, is adequate to address the subject fatigue cracking. The commenter points out that if the inspection finds no dents of a depth greater than 2 mm, no further action would be required; consequently, any subsequent detection of dents/cracking will depend upon the existing level and frequency of inspections in the operators existing maintenance program, specifically the Maintenance Planning Document (MPD). The commenter questions whether the inspections scheduled under the current MPD are adequate to ensure that any small dents are subsequently found and corrected in a timely manner.

The FAA responds to this comment by reiterating the circumstances relevant to the cracking addressed by this AD action. The subject cracks were detected on the rear pressure bulkhead on one airplane during a heavy maintenance check. The cracks were found to initiate from a dent in the bulkhead. Airbus conducted analyses and calculations of the dent and associated cracking, which demonstrated that:

1. the force necessary to make a dent of this sort in the rear pressure bulkhead in the specificlocation could not have been generated in service, and

2. the dent was unique to the production process.

The purpose of the one-time inspection required by this AD is to detect dents as small as 2 mm in depth in the rear pressure bulkhead that may have occurred during production. To accomplish this, the inspection makes use of a template in accordance with Airbus Service Bulletin A300-53-302, because the inspections conducted under the MPD cannot detect small dents of this type. The inspections that are part of the MPD are visual inspections, and are considered adequate to detect defects of the rear pressure bulkhead that may occur in service.

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 15 Airbus Model A300 series airplanes of U.S. registry will be affected by this AD, that it will take approximately 5 work hours per airplane to accomplish the required inspection for denting, 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 $4,500, or $300 per airplane.

If subsequent eddy current inspections to detect cracking are necessary, they would require 46 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of these inspections on U.S. operators is estimated to be $2,760 per airplane per inspection.

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: