[Federal Register Volume 62, Number 84 (Thursday, May 1, 1997)]
[Proposed Rules]
[Pages 23697-23699]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-11332]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 96-NM-170-AD]
RIN 2120-AA64
Airworthiness Directives; Airbus Model A300-600 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 A300-600
series airplanes. This proposal would require repetitive inspections to
detect fatigue cracking in the left and right wings in the area where
the top skin attaches to the center spar; and repair or modification of
this area, if necessary. This proposal is prompted by a report from the
manufacturer indicating that, during full-scale fatigue testing of the
airframe, fatigue cracking was detected in this area. The actions
specified by the proposed AD are intended to detect and correct this
cracking, which could reduce the residual strength of the top skin of
the wings, and consequently affect the structural integrity of the
airframe.
DATES: Comments must be received by June 12, 1997.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 96-NM-170-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: Charles Huber, Aerospace Engineer,
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate,
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206)
227-2589; 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-170-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-170-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, has notified the FAA that an unsafe
condition may exist on certain Airbus Model A300-600 series airplanes.
The DGAC advises that it has received a report from the manufacturer
indicating that, during full-scale fatigue testing of the airframe,
fatigue cracking was detected in an area of the wing where the top skin
attaches to the center spar between ribs 1 and 7. This cracking
originated in clearance fit fastener holes of joints between the skin
and the center
[[Page 23698]]
spar, and was detected between 33,000 and 49,000 simulated flights.
Initially, it was thought that this cracking was limited to a few
airplanes. The manufacturer, however, has found that cracking is more
widespread, and is apparently caused by shear stresses resulting from
loads on the landing gear.
This fatigue cracking, if not detected and corrected, could reduce
the residual strength of the top skin of the wings, and consequently
affect the structural integrity of the airframe.
Explanation of Relevant Service Information
Airbus has issued Service Bulletin A300-57-6044, Revision 2, dated
September 6, 1995, which describes procedures for conducting repetitive
inspections to detect fatigue cracking in the left and right wings in
the area where the top skin attaches to the center spar between ribs 1
and 7; and repair or modification of this area, if necessary.
The modification (Airbus Modification 10089) entails reinforcement
of this area and is intended to prevent cracking. If that modification
has not been installed prior to the initial inspection, operators must
inspect using either a detailed visual inspection or a high frequency
eddy current (HFEC) technique to detect fatigue cracking, and repair,
if necessary. Should cracking exceed 75 mm per rib bay, however, Airbus
recommends the installation of the modification. If Airbus Modification
10089 has been installed prior to the initial inspection, operators are
to conduct a low frequency eddy current inspection to detect fatigue
cracking of the inboard and rear edges of the top skin reinforcing
plate.
The Airbus service bulletin references Airbus Service Bulletin
A300-57-6041, Revision 4, dated November 16, 1995, as an additional
source of service information for installing Airbus Modification 10089.
The DGAC classified Airbus Service Bulletin A300-57-6044 as
mandatory and issued French airworthiness directive (C/N) 95-086-180(B)
R1, dated December 6, 1995, in order to assure the continued
airworthiness of these airplanes in France.
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 repetitive
inspections to detect fatigue cracking in the left and right wings in
the area where the top skin attaches to the center spar between ribs 1
and 7; and repair or modification of this area, if necessary.
Repair of cracking found on airplanes on which Airbus Modification
10089 has been accomplished would be required to be accomplished in
accordance with a method approved by the FAA. Other actions would be
required to be accomplished in accordance with Airbus Service Bulletin
A300-57-6044, described previously.
Cost Impact
The FAA estimates that 35 Airbus Model A300-600 series airplanes of
U.S. registry would be affected by this proposed AD.
For airplanes on which Airbus Modification 10089 has not been
installed, it would take approximately 2 hours to accomplish each
detailed visual inspection or 3 hours to accomplish each HFEC
inspection. The average labor rate is $60 per work hour.
Based on these figures, the cost impact of each proposed inspection
on U.S. operators is estimated to be either $120 or $180 per airplane,
depending on the type of inspection conducted.
For airplanes on which Airbus Modification 10089 has been
installed, it would take approximately 3 hours to accomplish each low
frequency eddy current inspection.
The average labor rate is $60 per work hour. Based on these
figures, the cost impact of each proposed inspection on U.S. operators
is estimated to be $180 per airplane.
The cost impact figures discussed above are 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: Docket 96-NM-170-AD.
Applicability: Model A300-600 series airplanes, on which Airbus
Modification 10160 has not been installed during production;
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 (c) of
this AD. The request should include an assessment of the effect of
the modification, alteration, or
[[Page 23699]]
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 in the left and right
wings in the area where the top skin attaches to the center spar,
which could reduce the residual strength of this skin, and
consequently affect the structural integrity of the airframe,
accomplish the following:
(a) For airplanes on which Airbus Modification 10089 has not
been installed: Prior to the accumulation of 18,000 total landings,
or within 1,500 landings after the effective date of this AD,
whichever occurs later, conduct either a detailed visual inspection
or a high frequency eddy current (HFEC) inspection to detect fatigue
cracking in the left and right wings in the area where the top skin
attaches to the center spar between ribs 1 and 7, in accordance with
Airbus Service Bulletin A300-57-6044, Revision 2, dated September 6,
1995.
(1) If no cracking is detected, conduct repetitive inspections
thereafter at the following intervals:
(i) If the immediately preceding inspection was conducted using
detailed visual techniques, conduct the next inspection within 5,000
landings.
(ii) If the immediately preceding inspection was conducted using
HFEC techniques, conduct the next inspection within 9,500 landings.
(2) If any cracking is detected or suspected during any detailed
visual inspection required by paragraph (a), (a)(1), or (a)(3)(i) of
this AD, prior to further flight, confirm this finding and the
length of this cracking by conducting a HFEC inspection, in
accordance with the service bulletin. If no cracking is confirmed
during the HFEC inspection, accomplish the repetitive inspection
required by paragraph (a)(1)(ii) of this AD at the time specified in
that paragraph.
(3) If any cracking is detected or confirmed during any HFEC
inspection required by paragraph (a), (a)(1), or (a)(2) of this AD:
(i) If the cracking is 75 mm or less per rib bay, prior to
further flight, repair in accordance with the service bulletin.
Thereafter, conduct repetitive detailed visual inspections of the
repaired area at intervals not to exceed 50 landings, in accordance
with the service bulletin.
(ii) If the cracking exceeds 75 mm per rib bay, prior to further
flight, install Airbus Modification 10089, in accordance with the
service bulletin. Thereafter, conduct a low frequency eddy current
inspection in accordance with the requirements of paragraph (b) of
this AD.
Note 2: The Airbus service bulletin references Airbus Service
Bulletin A300-57-6041, Revision 4, dated November 16, 1995, as an
additional source of service information for installing Airbus
Modification 10089.
(b) For airplanes on which Airbus Modification 10089 has been
installed: Prior to the accumulation of 22,000 total landings after
this modification has been installed, or within 1,500 landings after
the effective date of this AD, whichever occurs later, conduct a low
frequency eddy current inspection to detect fatigue cracking in the
inboard and rear edges of the top skin reinforcing plates, in
accordance with Airbus Service Bulletin A300-57-6044, Revision 2,
dated September 6, 1995.
(1) If no cracking is detected, repeat this inspection
thereafter at intervals not to exceed 11,000 landings.
(2) If any cracking is detected, prior to further flight, repair
in accordance with a method approved by the Manager, Standardization
Branch, ANM-113, FAA, Transport Airplane Directorate. Thereafter,
repeat this inspection at intervals not to exceed 11,000 landings.
(c) 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.
(d) 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 April 25, 1997.
Neil D. Schalekamp,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 97-11332 Filed 4-30-97; 8:45 am]
BILLING CODE 4910-13-U
