[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]
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