AD 2000-07-22

This amendment adopts a new airworthiness directive (AD), applicable to certain Airbus Model A300-600 series airplanes, that requires repetitive inspections to detect cracking of the doubler angle and discrepancies of the fasteners that connect the doubler angle and the bottom panel of the center wing box, and corrective actions, if necessary. This amendment is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by this AD are intended to detect and correct fatigue cracking in the doubler angle and discrepancies of the fasteners that connect the doubler angle and the bottom panel of the center wing box. Such cracking and discrepancies could result in reduced structural integrity of the airplane.

Final rule.

2000-07-22 AIRBUS INDUSTRIE: Amendment 39-11676. Docket 98-NM-78-AD.
Applicability: Model A300-600 series airplanes, on which Airbus Modification 11044 or Airbus Modification 11045 (reference Airbus Service Bulletin A300-53-6063, dated December 12, 1996) has not been accomplished, 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 (f) 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 detect and correct fatigue cracking of the doubler angle and discrepancies of the fasteners that connect the doubler angle and the bottom panel of the center wing box, which could result in reduced structural integrity of the airplane, accomplish the following:

Inspections
(a) Perform a detailed visual inspection to detect cracking of the doubler angle, and a detailed external visual inspection to detect discrepancies of the fasteners that connect the doubler angle and the bottom panel of the center wing box, on the left and right sides of the airplane, in accordance with Airbus Service Bulletin A300-53-6110, Revision 01, dated December 10, 1998, at the time specified in paragraph (a)(1) or (a)(2) of this AD, as applicable. Thereafter, repeat the inspections of the doubler angle and fasteners at intervals not to exceed 2,400 flight cycles.

(1) For airplanes on which a detailed visual inspection has been performed within the last 2,400 flight cycles prior to the effective date of this AD, in accordance with Structural Significant Item (SSI) 57-10-19 of the Airbus A300-600 Maintenance Review Board (MRB) Document: Inspect within 2,400 flight cycles after the most recent SSI inspection.

(2) For airplanes on which a detailed visual inspection has not been performed within the last 2,400 flight cycles prior to the effective date of this AD, in accordance with Structural Significant Item (SSI) 57-10-19 of the Airbus A300-600 Maintenance Review Board (MRB) Document: Inspect at the time specified in paragraph (a)(2)(i), (a)(2)(ii), or (a)(2)(iii), as applicable.

(i) For airplanes that have accumulated 6,600 or more total flight cycles as of the effective date of this AD: Inspect within 750 flight cycles after the effective date of this AD.

(ii) For airplanes that have accumulated more than 3,100 total flight cycles, but less than 6,600 total flight cycles as of the effective date of this AD: Inspect within 1,500 flight cycles after the effective date of this AD.

(iii) For airplanes that have accumulated 3,100 total flight cycles or less as of the effective date of this AD: Inspect prior to the accumulation of 4,600 total flight cycles.

NOTE 2: Accomplishment of inspections or corrective actions prior to the effective date of this AD, in accordance with Airbus Service Bulletin A300-53-6110, dated April 8, 1997, is acceptable for initial compliance with the applicable paragraph of this AD.

NOTE 3: For the purposes of this AD, a detailed visual inspection is defined as: "An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required."

Corrective Actions
(b) If any discrepancy is found in a fastener that connects the doubler angle and the bottom panel of the center wing box during any detailed external visual inspection performed in accordance with paragraph (a) of this AD: Prior to further flight, remove the discrepant fastener, and perform a rotating probe inspection to detect discrepancies of the fastener holes, in accordance with Airbus Service Bulletin A300-53-6110, Revision 01, dated December 10, 1998.

(1) If no discrepancy is found in any fastener hole, prior to further flight, install a new fastener, in accordance with the service bulletin. Thereafter, repeat the inspections required by paragraph (a) of this AD at intervals not to exceed 2,400 flight cycles.

(2) If any discrepancy is found in any fastener hole, prior to further flight, except as provided by paragraph (e) of this AD, repair in accordance with the service bulletin, and accomplish the actions required by paragraph (c) of this AD.

(c) If any crack is found in the doubler angle during any detailed visual inspection performed in accordance with paragraph (a) of this AD, accomplish paragraph (c)(1) or (c)(2), as applicable, at the time specified in that paragraph.

(1) If the cracking is within the limits specified in Figure 1, Sheet 1, of Airbus Service Bulletin A300-53-6110, Revision 01, dated December 10, 1998: Except as required by paragraph (e) of the AD, accomplish the applicable corrective actions (e.g., crack stopping of hole, rotating probe inspection, repetitive detailed visual inspections, eventual modification of doubler angle) specified in Figure 1, Sheet 1; at the times and in accordance with the procedures specified in the service bulletin.

(2) If the cracking is outside the limits specified in Figure 1, Sheet 1 [i.e., 1.181 inches (30 millimeters) or more in length]: Prior to further flight, modify the doubler angle in accordance with Airbus Service Bulletin A300-53-6063, dated December 12, 1996. Accomplishment of the modification constitutes terminating action for the repetitive inspection requirements of this AD.

Optional Terminating Modification
(d) Accomplishment of the modification in accordance with Airbus Service Bulletin A300-53-6063, dated December 12, 1996, constitutes terminating action for the repetitive inspection requirements of this AD.

Approved Repairs
(e) If any discrepancy is found during any inspection required by this AD, and the service bulletin specifies to contact Airbus for appropriate action: Prior to further flight, repair in accordance with a method approved by either the Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate, or the Direction G n rale de l'Aviation Civile (DGAC) (or its delegated agent). For a repair method to be approved by the Manager, InternationalBranch, ANM 116, as required by this paragraph, the Manager's approval letter must specifically reference this AD.

Alternative Methods of Compliance
(f) 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, International Branch, ANM-116. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, International Branch, ANM-116.

NOTE 4: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the International Branch, ANM-116.

Special Flight Permits
(g) 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.

IncorporationBy Reference
(h) Except as required by paragraph (e) of this AD, the actions shall be done in accordance with Airbus Service Bulletin A300-53-6110, Revision 01, dated December 10, 1998, or Airbus Service Bulletin A300-53-6063, dated December 12, 1996; as applicable. 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.

NOTE 5: The subject of this AD is addressed in French airworthiness directive 97-383-240(B), dated December 17, 1997.

(i) This amendment becomes effective on May 19, 2000.

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 A300-600 series airplanes was published in the Federal Register on May 19, 1998 (63 FR 27516). That action proposed to require repetitive inspections to detect cracking of the doubler angle and discrepancies of the fasteners that connect the doubler angle and the bottom panel of the center wing box, and corrective actions, if necessary.

Comments Received
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

No Objection to the Proposal
One commenter, an operator, states that it does not own or operate the equipment affected by the proposed AD, and as such, has no comments to offer.

Requests to Allow Continued Flight of an Airplane with Known Cracks
Three commenters,the manufacturer and two operators, request that the FAA revise the proposed AD to allow continued flight with a crack under 30 millimeters in length, provided that repetitive inspections are accomplished. These commenters state that analysis has shown that the structure can sustain ultimate load with the pickup angle completely cracked. Two of the commenters point out that the doubler angle is not a principal structural element (PSE). These commenters suggest that the FAA follow the continued flight criteria and angle replacement procedures described in Airbus Service Bulletin A300-53-6110, dated April 8, 1997 (which was referenced in the proposed AD as the appropriate source of service information for accomplishment of the inspection, repair, and installation of new fasteners). One of these commenters, an operator, states that such an allowance would enable scheduling of repairs in a manner that will minimize operational impact; without such an allowance, immediate field repairswould cost $15 million in out-of-service and maintenance costs.

The FAA concurs with the commenters' request to allow, under certain conditions, continued flight of airplanes with known cracks. Based on the substantiating data supplied by the commenters, and based on the circumstances of unusual need described above, the FAA has reconsidered its position regarding continued flight with known cracks for the affected airplanes. The FAA finds that allowing the affected airplanes to continue to fly with cracks that are within the limits specified in Airbus Service Bulletin A300-53-6110 is acceptable, provided that applicable corrective actions (e.g., crack stopping of hole, rotating probe inspection, repetitive detailed visual inspections, eventual modification of doubler angle) are accomplished as specified in Figure 1, Sheet 1, of that service bulletin. The FAA has revised paragraph (c) of the final rule to reflect this finding.

Request for an Alternative Method of Compliance
One commenter suggests that, as an alternative to the modification required by paragraph (c) of the proposed AD, operators be allowed to replace the existing part with a pre-modification 11045 doubler angle part with the same part number. The commenter states that, unlike the modification, such a replacement would be more expedient because it would not require jacking of the airplane. The commenter also states that, if the subject replacement is accomplished, the inspection program specified in Airbus Service Bulletin A300-53-6110 would still be required. The FAA does not concur. The FAA acknowledges that the doubler angle could be replaced by a pre- modified 11045 part if combined with the inspection program specified in Airbus Service Bulletin A300-53-6110. However, the Direction G n rale de l'Aviation Civile (DGAC), which is the airworthiness authority for France, has not definitively approved such a replacement scheme. Paragraph (f) of the final rule contains a provision for requesting approval of an alternative method of compliance on a case-by-case basis. No change to the final rule is necessary in this regard. Changes Made to the Proposed AD Since issuance of the proposed AD, Airbus Service Bulletin A300-53-6110, Revision 01, dated December 10, 1998, has been issued. This revision of the service bulletin is essentially equivalent to the original issue, dated April 8, 1997. The FAA has revised paragraphs (a), (b), and (c) of the AD to require accomplishment of the actions in those paragraphs in accordance with Revision 01 of the service bulletin. However, for operators that may have accomplished required actions prior to the effective date of this AD in accordance with the original issue of the service bulletin, "NOTE 2" has been added to the final rule to give credit for such accomplishment.

Operators should note that a fatigue rating has been added to Airbus Service Bulletin A300-53-6110, Revision 01, that is intended to allow operators to calculate an adjustable compliance threshold for accomplishment of the inspections described in the service bulletin. However, the FAA has determined that utilization of such "adjustment for range" calculations may present difficulties in determining if the applicable actions have been accomplished within the appropriate compliance time. While such adjustable compliance times are utilized as part of the Maintenance Review Board program, they do not fit practically into the AD tracking process for operators or for Principal Maintenance Inspectors attempting to ascertain compliance with AD's. Based on reviews of the "adjustment for range" calculations with the FAA Aircraft Evaluation Group, and in further consultation with the manufacturer, the FAA has determined that fixed compliance times should continue to be specified for accomplishment of the actions required by this AD. However, operators may request an extension of the compliance times of this AD in accordance with the "adjustment for range" formula, under the provisions of paragraph (f) of the final rule.

Because paragraph (c) of the final rule (which provides relief for corrective actions required in the event that cracking within certain limits is found) references paragraph (e), the FAA has revised paragraph (e) to address any case where a discrepancy is found during any inspection required by this AD and the service bulletin specifies to contact Airbus for appropriate action. In such a case, paragraph (e) requires that operators accomplish repairs prior to further flight in accordance with an FAA-approved method. The FAA also has determined that, in light of the type of actions that would be required to address the identified unsafe condition, and in consonance with existing bilateral airworthiness agreements, repair methods approved by either the FAA or the DGAC (or its delegated agent) would be acceptable for compliance with this AD. Accordingly, this provision is added to paragraph (e) of thefinal rule.

Additionally, the FAA has added "NOTE 3" to the final rule to clarify the definition of a detailed visual inspection.

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 with the changes described previously. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

Cost Impact
The FAA estimates that 54 Model A300-600 series airplanes of U.S. registry will be affected by this AD, that it will take approximately 2 work hours per airplane to accomplish the required inspections, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the inspection proposed by this AD on U.S. operators is estimated to be $6,480, or $120 per airplane, per inspection cycle.

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 substantialnumber 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: