Airworthiness Directives; Airbus Model A319, A320, and A321 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Airbus Model A320 series airplanes, that currently requires an initial inspection of fastener holes on certain outer frames of the fuselage to detect fatigue cracking, and modification of the area by cold expanding the holes and installing oversized fasteners. This action would revise the applicability to include additional airplanes; require a high frequency eddy current inspection to detect fatigue cracking in the frames and frame feet at fuselage frames FR37 through FR41; and follow-on actions. This proposal also provides for an optional terminating action for the follow-on repetitive inspections. This proposal is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by the proposed AD are intended to prevent fatigue cracking of the fuselage frames and frame feet, and consequent reduced structural integrity of the fuselage.

DATES:

Comments must be received by May 5, 2000.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-95-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal holidays.

The service information referenced in the proposed rule may be obtained from Airbus Industrie, 1 Rond Point Maurice Bellonte, 31707 Blagnac Cedex, France. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

Norman B. Martenson, Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2110; fax (425) 227-1149.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 99-NM-95-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-95-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

On May 12, 1997, the FAA issued AD 97-11-01, amendment 39-10030 (62 FR 28324, May 23, 1997), applicable to certain Airbus Model A320 series airplanes, to require an initial inspection of fastener holes on certain outer frames of the fuselage to detect fatigue cracking, and modification of the area by cold expanding the holes and installing oversized fasteners. That action was prompted by a report from the manufacturer indicating that, during full-scale fatigue testing of the test article, fatigue cracking was detected in the area where the center fuselage joins the wing. The requirements of that AD are intended to prevent fatigue cracking and consequent reduced structural integrity of this area, which could lead to rapid depressurization of the fuselage.

Actions Since Issuance of Previous Rule

The Direction Generale de l'Aviation Civile (DGAC), which is the airworthiness authority for France, has advised the FAA that, during accomplishment of the eddy current rotating probe inspection to detect fatigue cracking of fastener holes on certain outer frames of the fuselage (required by AD 97-11-01), some operators have reported also finding cracks in the frame and frame feet at fuselage frames FR37 through FR41, stringer 23. This condition, if not detected and corrected, could result in reduced structural integrity of the fuselage.

Explanation of Relevant Service Information

Airbus has issued Service Bulletin A320-53-1141, Revision 1, dated October 4, 1999. This service bulletin describes procedures for conducting a high frequency eddy current (HFEC) inspection to detect fatigue cracking in the frames and frame feet at fuselage frames FR37 through FR41, and follow-on actions. For cases where no cracking is detected, the follow-on actions include one of the following: (1) Repetitive inspections; (2) the modifications specified in Airbus Service Bulletin A320-53-1128 described below; or (3) if applicable, modification of certain fastener holes of the fuselage frames FR37 through FR41 adjacent to stringer 23, and follow-on repetitive inspections. For certain cracking conditions, the follow-on actions involve a bushing repair, or accomplishment of the modifications in Airbus Service Bulletin A320-53-1128. For certain other cracking conditions, the follow-on actions involve simultaneous replacement of the frame segment or frame foot with a new frame segment or frame foot and accomplishment of the modifications in Airbus Service Bulletin A320-53-1128.

Airbus also has issued Service Bulletin A320-53-1128, Revision 01, including Appendix 01, both dated October 4, 1999. This service bulletin describes procedures for a rotating probe eddy current inspection to detect cracks in the fastener holes where the existing fasteners are removed; repair of the fastener hole; installation of four doublers on each frame; cold working of certain fastener holes; installation of new fasteners in the cold-worked holes; and installation of new modified system brackets at fuselage frames FR37 through FR41. These modifications would improve the fatigue strength in the frame and frame feet of left and right fuselage frames FR37 through FR41, and would eliminate the need for the repetitive HFEC inspections in this area.

Accomplishment of the actions specified in the service bulletins is intended to adequately address the identified unsafe condition. The DGAC classified both of these service bulletins as mandatory for certain actions, recommended Airbus Service Bulletin A320-53-1128 for certain other actions, and issued French airworthiness directive 98-509-123(B), dated December 16, 1998, in order to assure the continued airworthiness of these airplanes in France.

FAA's Conclusions

These airplane models are manufactured in France and are type certificated for operation in the United States under the provisions of § 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, the DGAC has kept the FAA informed of the situation described above. The FAA has examined the findings of the DGAC, reviewed all available information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design registered in the United States, the proposed AD would supersede AD 97-11-01 to require an HFEC inspection to detect fatigue cracking in the frames and frame feet of left and right fuselage frames FR37 through FR41; and follow-on actions. This proposal also would allow for an optional terminating action for the follow-on repetitive inspections. The actions would be required to be accomplished in accordance with the service bulletins described previously, except as discussed below.

Differences Between Proposed Rule and Service Bulletin

Operators should note that, unlike the procedures described in Airbus Service Bulletin A320-53-1141, this proposed AD would not permit further flight if cracks are detected in the frame or frame feet. The FAA has determined that, because of the safety implications and consequences associated with such cracking, any subject frames or frame feet that are found to be cracked must be repaired or modified prior to further flight.

Operators also should note that, in consonance with the findings of the DGAC, the FAA has determined that the repetitive inspections proposed by this AD can be allowed to continue in lieu of accomplishment of a terminating action. In making this determination, the FAA considers that, in this case, long-term continued operational safety will be adequately assured by accomplishing the repetitive inspections to detect cracking before it represents a hazard to the airplane.

Cost Impact

There are approximately 198 airplanes of U.S. registry that would be affected by this proposed AD.

The new HFEC inspection that is proposed in this AD action would 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 proposed requirements of this AD on U.S. operators is estimated to be $23,760, 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 current or proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted.

Should an operator elect to accomplish the optional terminating action rather than continue the repetitive inspections, it would take between 297 and 316 work hours per airplane to accomplish the inspection and modification, at an average labor rate of $60 per work hour. Required parts would cost between $40 and $5,290 per airplane. Based on these figures, the cost impact of this optional terminating action is estimated to be between $17,860 and $24,250 per airplane.

Regulatory Impact

The regulations proposed herein would not have a substantial direct effect 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, it is determined that this proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this proposed regulation (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, 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 copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 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.