[Federal Register Volume 62, Number 34 (Thursday, February 20, 1997)]
[Proposed Rules]
[Pages 7727-7729]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-4101]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-106-AD]
RIN 2120-AA64


Airworthiness Directives; Airbus Model A320 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain Airbus Model A320 series 
airplanes. This proposal would require an initial inspection of 
fastener holes on certain outer frames of the fuselage to detect 
fatigue cracking, and modification of this area by cold expanding these 
holes and installing oversized fasteners. This proposal is 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 actions 
specified by the proposed AD are intended to prevent fatigue cracking 
and consequent reduced structural integrity of this area, which could 
lead to rapid depressurization of the fuselage.

DATES: Comments must be received by March 31, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-106-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: Tim Backman, Aerospace Engineer, 
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue SW, Renton, Washington 98055-4056; telephone (206) 
227-2797; fax (206) 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 96-NM-106-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-103, Attention: Rules 
Docket No. 96-NM-106-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The Direction Generale de l'Aviation Civile (DGAC), which is the 
airworthiness authority for France, recently notified the FAA that an 
unsafe condition may exist on certain Airbus Model A320 series 
airplanes. The DGAC advises that it has received a report from the 
manufacturer indicating that fatigue cracks were detected during full-
scale fatigue testing of the test article after 90,001 simulated 
flights. These cracks were found in fastener holes in the flange caps 
of outer right frame 40 and outer left frame 41, adjacent to Stringer 
23; this is the area where the center fuselage joins the wing. This 
condition, if not prevented, consequently could reduce the structural 
integrity of this area, and lead to rapid decompression of the 
fuselage.

Explanation of Related and Relevant Service Information

    Airbus has issued Service Bulletin A320-53-1026, dated August 5, 
1994, which describes procedures for conducting repetitive eddy current 
rotating probe inspections of fastener holes on certain outer frames of 
the fuselage to detect fatigue cracking and repair, if necessary. These 
holes are located on the forward and aft faces of the flange caps on 
outer left and right frames 37 through 41, adjacent to Stringer 23; 
this is the area where the center fuselage joins the wing.

[[Page 7728]]

    Airbus also has issued Service Bulletin A320-53-1025, Revision 1, 
dated November 24, 1994, which describes procedures for conducting an 
initial eddy current rotation probe inspection of these fastener holes 
to detect fatigue cracking, and for modification of this area by cold 
expanding certain holes and installing oversized fasteners. This 
modification, which would improve the resistance of this area to 
fatigue cracking, would eliminate the need for repetitive eddy current 
inspections of this area.
    The DGAC classified Airbus Service Bulletin A320-53-1026 as 
mandatory and issued French airworthiness directive (CN) 95-101-69(B), 
dated May 24, 1995, in order to assure the continued airworthiness of 
these airplanes in France. The DGAC classified Airbus Service Bulletin 
A320-53-1025 as ``recommended,'' but indicated in CN 95-101-69(B) that 
accomplishment of this service bulletin would terminate the repetitive 
eddy current inspections required by that C/N.

FAA's Conclusions

    This airplane model is manufactured in France and is type 
certificated for operation in the United States under the provisions of 
section 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 require an initial eddy 
current rotation probe inspection to detect fatigue cracking in certain 
fastener holes in the area where the center fuselage joins the wing, 
and a modification to improve the resistance of this area to fatigue 
cracking. The modification entails the cold expansion of certain 
fastener holes and the installation of oversized fasteners in these 
holes. The actions would be required to be accomplished in accordance 
with the Airbus service bulletins described previously.

Differences Between the Proposed Rule and the French CN

    Under the FAA's proposed AD, operators would be required to modify 
the area where the center fuselage joins the wing by cold expanding 
certain fastener holes and installing oversized fasteners in these 
holes. The DGAC has not mandated this modification, but instead, has 
mandated repetitive inspections of the area.
    The adequacy of inspections needed to maintain the safety of the 
transport airplane fleet, coupled with a better understanding of the 
human factors associated with numerous repetitive inspections, has 
caused the FAA to place less emphasis on repetitive inspections, and 
more emphasis on design improvements and material replacement. Thus, 
the FAA has decided to require, whenever practicable, modifications 
necessary to remove the source of the problem addressed. The 
modification requirement of this proposed AD is in consonance with that 
decision.

Cost Impact

    The FAA estimates that 24 Airbus Model A320 series airplanes of 
U.S. registry would be affected by this proposed AD.
    It would take approximately 25 work hours per airplane to 
accomplish the proposed actions, at an average labor rate of $60 per 
work hour. Required parts would cost approximately $557 per airplane. 
Based on these figures, the cost impact of the proposed AD on U.S. 
operators is estimated to be $49,368, or $2,057 per airplane.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the proposed 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 proposed herein would 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 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    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.


Sec. 39.13   [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

Airbus Industrie: Docket 96-NM-106-AD.

    Applicability: Model A320 series airplanes as listed in Airbus 
Service Bulletin A320-53-1026, dated August 5, 1994; on which 
modifications 21281P1495 and 21680P1818 have 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 
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 (e) 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 in the area where the center 
fuselage joins the wing, which could reduce the structural integrity 
of this area and consequently result in rapid decompression of the 
fuselage, accomplish the following:
    (a) Prior to the accumulation of 16,000 total landings, or 
within 6 months after the effective date of this AD, whichever 
occurs

[[Page 7729]]

later, perform an eddy current rotating probe inspection to detect 
fatigue cracking in the fastener holes of the outer frame flanges of 
left and right fuselage frames 37 through 41, adjacent to Stringer 
23, in accordance with Airbus Service Bulletin A320-53-1026, dated 
August 5, 1994.

    Note 2: Prior to the effective date of this AD, accomplishment 
of any modification in accordance with Airbus Service Bulletin A320-
53-1025, dated August 5, 1994, is considered acceptable for 
compliance with the modification requirements of paragraphs (b), 
(c)(1)(i), (c)(2) and (d) of this AD.

    (b) If the inspection required by paragraph (a) of this AD 
detects no cracking in any hole: Prior to the accumulation of 6,000 
landings after this inspection, modify each hole in accordance with 
Paragraph 2.B.(5) of Airbus Service Bulletin A320-53-1025, Revision 
1, dated November 24, 1994. Thereafter, no further action is 
required by this AD.
    (c) If the inspection required by paragraph (a) of this AD 
detects any cracking in no more than one hole per frame cap, 
accomplish the requirements of paragraph (c) (1) and (c)(2) of this 
AD:
    (1) Prior to further flight, repair this cracked hole and 
conduct another rotating probe inspection of this hole to detect 
cracking, in accordance with Paragraph 2.B.(6) of Airbus Service 
Bulletin A320-53-1025, Revision 1, dated November 24, 1994.
    (i) If no cracking of this repaired hole is detected: Prior to 
further flight, modify this hole in accordance with Paragraph 
2.B.(6)(c) of this service bulletin. Thereafter, no further action 
with regard to this hole is required by this AD.
    (ii) If any cracking of this repaired hole is detected: Prior to 
further flight, repair this hole in a manner approved by the 
Manager, Standardization Branch, ANM-113, FAA, Transport Airplane 
Directorate. Thereafter, no further action with regard to this hole 
is required by this AD.
    (2) Prior to the accumulation of 6,000 landings after the 
inspection required by paragraph (a) of this AD; modify all other 
holes in accordance with Paragraph 2.B.(5) of Airbus Service 
Bulletin A320-53-1025, Revision 1, dated November 24, 1994. 
Thereafter, no further action is required by this AD with respect to 
these holes.
    (d) If the inspection required by paragraph (a) of this AD 
detects any cracking in more than one hole per frame cap, or if this 
inspection detects any cracking in any frame: Prior to further 
flight, repair the discrepant area in a manner approved by the 
Manager, Standardization Branch, ANM-113; and modify all other holes 
in accordance with Paragraph 2.B.(5) of Airbus Service Bulletin 
A320-53-1025, Revision 1, dated November 24, 1994. Thereafter, no 
further action is required by this AD.
    (e) 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 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Standardization Branch, ANM-113.

    (f) 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.

    Issued in Renton, Washington, on February 12, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-4101 Filed 2-19-97; 8:45 am]
BILLING CODE 4910-13-U