[Federal Register Volume 63, Number 166 (Thursday, August 27, 1998)]
[Proposed Rules]
[Pages 45775-45777]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-22961]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-161-AD]
RIN 2120-AA64


Airworthiness Directives; Aerospatiale Model SN 601 (Corvette) 
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 Aerospatiale Model SN 601 
(Corvette) series airplanes. This proposal would require repetitive 
inspections to detect discrepancies of the upper and lower 
reinforcement panels and panel fasteners of the wing roots; and 
corrective actions, if necessary. 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 debonding of the upper and lower reinforcement 
panels of the wing roots, which could result in reduced structural 
integrity of the wing.

DATES: Comments must be received by September 28, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-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 Aerospatiale, 316 Route de Bayonne, 31060 Toulouse, Cedex 
03, 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 98-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-114, Attention: Rules 
Docket No. 98-NM-161-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

[[Page 45776]]

Discussion

    The Direction Generale de l'Aviation Civile (DGAC), which is the 
airworthiness authority for France, notified the FAA that an unsafe 
condition may exist on certain Aerospatiale Model SN 601 (Corvette) 
series airplanes. The DGAC advises that it has received reports of 
debonding of the upper and lower surface reinforcement panels of the 
wing roots on these airplanes. The debonding has been attributed to 
water infiltration. This condition, if not corrected, could result in 
fatigue damage of the panel fasteners and corrosion of the panels and 
wing structure, and consequent reduced structural integrity of the 
wing.

Explanation of Relevant Service Information

    The manufacturer has issued Aerospatiale Corvette Service Bulletin 
57-24, Revision 1, dated May 30, 1994. This service bulletin describes 
procedures for removal of the left and right lateral fairings between 
frames 16 and 22; repetitive sonic resonance inspections to detect 
debonding of the upper and lower surface reinforcement panels of the 
wing root; and repetitive visual inspections to detect damage of the 
reinforcement panel fasteners.
    In addition, Aerospatiale has issued Corvette Service Bulletin 57-
25, dated November 21, 1990, which describes procedures for replacement 
of the upper and lower surface reinforcement panels of the wing root 
and treatment of the area for corrosion if excessive debonding or 
fastener damage is found during an inspection described in Aerospatiale 
Corvette Service Bulletin 57-24.
    The DGAC classified these service bulletins as mandatory and issued 
French airworthiness directive 91-045-010(B)R1, dated August 3, 1994, 
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 accomplishment of 
the actions specified in the service bulletins described previously, 
except as discussed below.

Differences Between Proposed Rule and Service Bulletin

    Operators should note that, although Aerospatiale Corvette Service 
Bulletin 57-24 specifies that the manufacturer may be contacted for 
disposition of certain repair conditions, this proposal would require 
the repair of those conditions to be accomplished in accordance with a 
method approved by either the FAA or the DGAC (or its delegated agent). 
In light of the type of repair that would be required to address the 
identified unsafe condition, and in consonance with existing bilateral 
airworthiness agreements, the FAA has determined that, for this 
proposed AD, a repair approved by either the FAA or the DGAC would be 
acceptable for compliance with this proposed AD.

Cost Impact

    The FAA estimates that 1 airplane of U.S. registry would be 
affected by this proposed AD, that it would take approximately 2 work 
hours to accomplish the proposed inspection, and that the average labor 
rate is $60 per work hour. Based on these figures, the cost impact of 
the proposed AD on the single U.S. operator is estimated to be $120, 
per inspection cycle.
    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:

Aerospatiale: Docket 98-NM-161-AD.

    Applicability: Model SN 601 (Corvette) series airplanes on which 
Aerospatiale Modification 1049 has 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 (c) 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 debonding of the upper and lower reinforcement panels 
of the wing roots, which could result in reduced structural 
integrity of the wing, accomplish the following:
    (a) For airplanes that have been modified in accordance with 
Aerospatiale Corvette Service Bulletin 57-25, dated November 21, 
1990: Within 8,300 flight cycles after installation of the 
modification, or within 100 flight cycles after the effective date 
of

[[Page 45777]]

this AD, whichever occurs later, perform a sonic resonance 
inspection to detect debonding of the upper and lower reinforcement 
panels of the wing roots and a visual inspection to detect fatigue 
damage of the panel fasteners, in accordance with the Accomplishment 
Instructions of Aerospatiale Corvette Service Bulletin 57-24, 
Revision 1, dated May 30, 1994.
    (1) If no panel debonding or fastener damage is found, repeat 
the sonic resonance inspection and the visual inspection thereafter 
at intervals not to exceed 1,000 flight cycles.
    (2) If any panel debonding or fastener damage is found, prior to 
further flight, repair in accordance with a method approved by 
either the Manager, International Branch, ANM-116, or the Direction 
Gonorale de l'Aviation Civile (DGAC), which is the airworthiness 
authority for France (or its delegated agent).
    (b) For airplanes that have not been modified in accordance with 
Aerospatiale Corvette Service Bulletin 57-25, dated November 21, 
1990: Prior to the accumulation of 8,200 total flight cycles, or 
within 100 flight cycles after the effective date of this AD, 
whichever occurs later, perform a sonic resonance inspection to 
detect debonding of the upper and lower reinforcement panels of the 
wing roots, and a visual inspection to detect fatigue damage of the 
panel fasteners, in accordance with the Accomplishment Instructions 
of Aerospatiale Corvette Service Bulletin 57-24, Revision 1, dated 
May 30,
1994.
    (1) For any reinforcement panel on which no debonding or 
fastener damage is found, repeat the sonic resonance inspection and 
the visual inspection thereafter at intervals not to exceed 2,500 
flight cycles or three years, whichever occurs first.
    (2) For any reinforcement panel on which debonding is detected, 
and the total debonded area is less than or equal to 45% of the 
total area, and no contiguous debonded area on the panel is greater 
than 5% of the total area of the panel, repeat the sonic resonance 
inspection and the visual inspection thereafter at the interval 
specified in paragraph (b)(2)(i), (b)(2)(ii), or (b)(2)(iii), as 
applicable, of this AD.
    (i) If the total debonded area on the panel is less than or 
equal to 10% of the total area, repeat the inspections of that panel 
thereafter at intervals not to exceed 2,500 flight cycles or 3 
years, whichever occurs first.
    (ii) If the total debonded area on the panel is greater than 10% 
and less than or equal to 30% of the total area, repeat the 
inspections of that panel thereafter at intervals not to exceed 
2,000 flight cycles or 3 years, whichever occurs first.
    (iii) If the total debonded area of the panel is greater than 
30% and less than or equal to 45% of the total area, repeat the 
inspections of that panel thereafter at intervals not to exceed 
1,000 flight cycles or 2 years, whichever occurs first.
    (3) For any reinforcement panel on which debonding is detected, 
and the total debonded area of the panel is greater than 45% of the 
total area, or if any single debonded area on any single panel is 
greater than 5% of the total area of that panel, or if any panel 
fastener damage is detected, accomplish the actions specified in 
paragraphs (b)(3)(i) and (b)(3)(ii) of this AD.
    (i) Prior to further flight, inspect the skin to determine the 
level of corrosion relative to the skin thickness in accordance with 
a method approved by either the Manager, International Branch, ANM-
116, or the DGAC (or its delegated agent).
    (A) If the depth of corrosion of the skin is less than or equal 
to 10% of the skin thickness, remove and replace the panel and treat 
the skin for corrosion, in accordance with the Accomplishment 
Instructions of Aerospatiale Corvette Service Bulletin 57-25, dated 
November 21, 1990.
    (B) If the depth of corrosion of the skin exceeds 10% of the 
skin thickness, repair in accordance with a method approved by the 
Manager, International Branch, ANM-116, or in accordance with a 
method approved by the DGAC (or its delegated agent).
    (ii) For airplanes on which the actions of paragraph 
(b)(3)(i)(A) of this AD have been accomplished: Within 8,300 flight 
cycles after accomplishment of paragraph (b)(3)(i)(A) of this AD, 
perform a sonic resonance inspection to detect debonding of the 
panel and a visual inspection to detect fatigue damage of the panel 
fasteners, in accordance with the Accomplishment Instructions of 
Aerospatiale Corvette Service Bulletin 57-24, Revision 1, dated May 
30, 1994.
    (A) If no debonding or fastener damage is found, repeat the 
inspection thereafter at intervals not to exceed 1,000 flight 
cycles.
    (B) If any debonding or fastener damage is detected, prior to 
further flight, repair in accordance with a method approved by the 
Manager, International Branch, ANM-116, or in accordance with a 
method approved by the DGAC (or its delegated agent).
    (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, International Branch, ANM-116. 
Operators shall submit their requests through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, International Branch, ANM-116.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the International Branch, ANM-116.

    (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.

    Note 3: The subject of this AD is addressed in French 
airworthiness directive 91-045-010(B)R1, dated August 3, 1994.

    Issued in Renton, Washington, on August 20, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-22961 Filed 8-26-98; 8:45 am]
BILLING CODE 4910-13-U