[Federal Register Volume 61, Number 40 (Wednesday, February 28, 1996)]
[Proposed Rules]
[Pages 7444-7446]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-4509]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 95-NM-161-AD]
Airworthiness Directives; Airbus Model A300 B2 and B4 Series
Airplanes, Excluding 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 B2 and
B4 series airplanes. This proposal would require measurements of the
thickness of the inner skin of the longitudinal lap joint from the
inside of the fuselage at certain stringers. The proposed AD would also
require inspections to detect stress corrosion cracking in the subject
area, and repair, if necessary. This proposal is prompted by reports of
corrosion cracking found in the skin at the longitudinal lap joint at
certain stringers of the fuselage, which was caused by the increased
stress level in the subject area when it was reworked beyond certain
limits. The actions specified by the proposed AD are intended to
prevent such stress corrosion cracking which, if not detected and
corrected in a timely manner, could result in rapid depressurization of
the airplane.
DATES: Comments must be received by April 8, 1996.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport
[[Page 7445]]
Airplane Directorate, ANM-103, Attention: Rules Docket No. 95-NM-161-
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 95-NM-161-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. 95-NM-161-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 A300 B2 and B4
series airplanes. The DGAC advises that, during regularly scheduled
maintenance of two in-service airplanes, significant skin cracking was
found in the longitudinal lap joint at stringer 57 between frames 67
and 68 of the fuselage. One of the airplanes had accumulated 23,893
total flight hours and 22,936 total flight cycles. The other airplane
had accumulated 28,957 total flight hours and 23,574 total flight
cycles.
Investigation revealed that the subject area on these airplanes,
including the longitudinal lap joint at stringer 52, had been reworked
to remove corrosion. However, the rework removed far more material than
that allowed by the Structural Repair Manual (SRM). Such reduction in
the thickness of the material increases the stress level in the skin.
This condition, in conjuction with a corrosive environment, renders the
subject area susceptible to stress corrosion cracking. Stress corrosion
cracking in the longitudinal lap joints of the fuselage, if not
detected and corrected in a timely manner, could result in rapid
depressurization of the airplane.
Airbus has issued All Operator Telex (AOT) AOT 53-05, Revision 1,
dated August 16, 1993. The AOT describes procedures for measurements of
the thickness of the inner skin of the longitudinal lap joint from the
inside of the fuselage at stringer 57 between frames 65 and 72, and at
stringer 52 (left- and right-hand) between frames 58 and 65. The
measurement involves using an ultrasonic thickness measurement method.
The AOT also describes procedures for high frequency eddy current
(HFEC) inspections to detect cracking in the subject area. The DGAC
classified this AOT as mandatory and issued French airworthiness
directive 93-150-147(B), dated September 1, 1993, in order to assure
the continued airworthiness of these airplanes in France.
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.
Since an unsafe condition has been identified that is likely to
exist or develop on other airplanes of the same type design, the
proposed AD would require measurements of the thickness of the inner
skin of the longitudinal lap joint from the inside of the fuselage at
certain stringers using the ultrasonic thickness measurement method.
The proposed AD would also require HFEC inspections to detect cracking
in the subject area. The actions would be required to be accomplished
in accordance with the AOT described previously. If any crack is found
or if the thickness of the inner skin is less than or equal to certain
limits, it would be required to be repaired in accordance with a method
approved by the FAA.
The FAA estimates that 17 airplanes of U.S. registry would be
affected by this proposed AD, that it would take approximately 32 work
hours per airplane to accomplish the proposed actions, and that the
average labor rate is $60 per work hour. Based on these figures, the
cost impact of the proposed AD on U.S. operators is estimated to be
$32,640, or $1,920 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.
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.
[[Page 7446]]
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 USC 106(g) 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
Airbus Industrie: Docket 95-NM-161-AD.
Applicability: Model A300 B2 and B4 series airplanes, excluding
Model A300-600 series airplanes; manufacturer serial numbers 003
through 156 inclusive; on which Airbus Modification 2611 has 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 stress corrosion cracking in the longitudinal lap
joints of the fuselage, which could result in rapid depressurization
of the airplane, accomplish the following:
Note 2: Any of the inspections and measurements required by this
AD that were performed before the effective date of this AD in
accordance with Airbus All Operator Telex (AOT) 53-05 (original
issue), dated August 16, 1995, are considered acceptable for
compliance with the applicable requirements of this AD.
(a) Within 60 days after the effective date of this AD,
accomplish paragraphs (a)(1) and (a)(2) of this AD in accordance
with Airbus All Operator Telex (AOT) 53-05, Revision 1, dated August
16, 1993.
(1) Measure the thickness of the inner skin of the longitudinal
lap joint from the inside of the fuselage at stringer 57 between
frames 65 and 72 using the ultrasonic thickness measurement method,
in accordance with the AOT. If the thickness is less than or equal
to the limits specified in the AOT, prior to further flight, repair
the longitudinal lap joint in accordance with a method approved by
the Manager, Standardization Branch, ANM-113, FAA, Transport
Airplane Directorate.
(2) Perform a high frequency eddy current (HFEC) inspection to
detect cracking of the longitudinal lap joint at stringer 57 between
frames 65 and 72, in accordance with the AOT. If any cracking is
detected, prior to further flight, repair the longitudinal lap joint
in accordance with a method approved by the Manager, Standardization
Branch, ANM-113.
(b) Within 6 months after the effective date of this AD,
accomplish paragraphs (b)(1) and (b)(2) of this AD in accordance
with Airbus AOT 53-05, Revision 1, dated August 16, 1993.
(1) Measure the thickness of the inner skin of the longitudinal
lap joint from the inside of the fuselage at stringer 52 (left- and
right-hand) between frames 58 and 65 using the ultrasonic thickness
measurement method, in accordance with the AOT. If the thickness is
less than or equal to the limits specified in the AOT, prior to
further flight, repair the longitudinal lap joint in accordance with
a method approved by the Manager, Standardization Branch, ANM-113.
(2) Perform a HFEC inspection to detect cracking of the
longitudinal lap joint at stringer 52 (left- and right-hand) between
frames 58 and 65, in accordance with the AOT. If any cracking is
detected, prior to further flight, repair the longitudinal lap joint
in accordance with a method approved by the Manager, Standardization
Branch, ANM-113.
(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,
FAA, Transport Airplane Directorate. 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 February 22, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-4509 Filed 2-27-96; 8:45 am]
BILLING CODE 4910-13-U
