[Federal Register Volume 64, Number 71 (Wednesday, April 14, 1999)]
[Proposed Rules]
[Pages 18384-18386]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-9252]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-CE-120-AD]
RIN 2120-AA64


Airworthiness Directives; LET Aeronautical Works Model L33 SOLO 
Sailplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes to adopt a new airworthiness directive 
(AD) that would apply to certain LET Aeronautical Works (LET) Model L33 
SOLO sailplanes. The proposed AD would require replacing the main wing 
attachment and wing spar root pins and modifying the corresponding 
area. The proposed AD is the result of mandatory continuing 
airworthiness information (MCAI) issued by the airworthiness authority 
for the Czech Republic. The actions specified by the proposed AD are 
intended to prevent structural failure of the wing attachments caused

[[Page 18385]]

by the current design configuration, which could result in the wing 
separating from the sailplane with consequent loss of control.

DATES: Comments must be received on or before May 19, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Central Region, Office of the Regional Counsel, 
Attention: Rules Docket No. 98-CE-120-AD, Room 1558, 601 E. 12th 
Street, Kansas City, Missouri 64106. Comments may be inspected at this 
location between 8 a.m. and 4 p.m., Monday through Friday, holidays 
excepted.
    Service information that applies to the proposed AD may be obtained 
from LET Aeronautical Works, 686 04 Kunovice, Czech Republic; 
telephone: +420 632 51 11 11; facsimile: +420 632 613 52. This 
information also may be examined at the Rules Docket at the address 
above.

FOR FURTHER INFORMATION CONTACT: Mr. Mike Kiesov, Aerospace Engineer, 
FAA, Small Airplane Directorate, 1201 Walnut, suite 900, Kansas City, 
Missouri 64106; telephone: (816) 426-6934; facsimile: (816) 426-2169.

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 should 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 that summarizes 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 No. 98-CE-120-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, Central Region, Office of the Regional Counsel, Attention: 
Rules Docket No. 98-CE-120-AD, Room 1558, 601 E. 12th Street, 
KansasCity, Missouri 64106.

Discussion

    The Civil Aviation Authority of the Czech Republic (CAA CZ), which 
is the airworthiness authority for the Czech Republic, notified the FAA 
that an unsafe condition may exist on certain LET Model L33 SOLO 
sailplanes. The CAA CZ reports that fatigue damage could occur to the 
main wing attachment over a certain period of time. LET performed 
fatigue testing that revealed deterioration and potential failure of 
these parts around 2,000 hours time-in-service (TIS).
    This condition, if not corrected in a timely manner, could result 
in the wing separating from the sailplane with consequent loss of 
control.

Relevant Service Information

    LET has issued Mandatory Bulletin Number L33/008a, dated January 
20, 1998, which specifies procedures for replacing the main wing 
attachment and wing spar root pins and modifying the corresponding 
area.
    The CAA CZ classified this service bulletin as mandatory and issued 
Czechoslovakian AD CCA-T-AD-1-024/98, dated March 23, 1998, in order to 
assure the continued airworthiness of these sailplanes in the Czech 
Republic.

The FAA's Determination

    This sailplane model is manufactured in the Czech Republic 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 CAA CZ has kept the FAA 
informed of the situation described above.
    The FAA has examined the findings of the CAA CZ; reviewed all 
available information, including the service information referenced 
above; and determined that AD action is necessary for products of this 
type design that are certificated for operation in the United States.

Explanation of the Provisions of the Proposed AD

    Since an unsafe condition has been identified that is likely to 
exist or develop in other LET Model L33 sailplanes of the same type 
design registered in the United States, the FAA is proposing AD action. 
The proposed AD would require replacing the main wing attachment and 
wing spar root pins and modifying the corresponding area. 
Accomplishment of the proposed AD would be required in accordance with 
the service information referenced previously.

Cost Impact

    The FAA estimates that 20 sailplanes in the U.S. registry would be 
affected by the proposed AD, that it would take approximately 35 
workhours per sailplane to accomplish the proposed action, and that the 
average labor rate is approximately $60 an hour. Parts cost 
approximately $900 per sailplane. Based on these figures, the total 
cost impact of the proposed AD on U.S. operators is estimated to be 
$60,000, or $3,000 per sailplane.

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 action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under 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 has been placed 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:

[[Page 18386]]

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 a new airworthiness directive 
(AD) to read as follows:

LET Aeronautical Works: Docket No. 98-CE-120-AD.

    Applicability: The following serial numbers of Model L33 SOLO 
sailplanes, certificated in any category:

930101 through 930205;
940310 through 940316;
950405 and 950406;
960407 and 960408; and
940206 through 940308;
950318 through 950401;
960402 through 960404;
960410

    Note 1: This AD applies to each sailplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For sailplanes 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 (d) 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 in the body of this AD, unless 
already accomplished.
    To prevent structural failure of the wing attachments caused by 
the current design configuration, which could result in the wing 
separating from the sailplane with consequent loss of control, 
accomplish the following:
    (a) Upon accumulating 1,500 hours time-in-service (TIS) on each 
wing attachment or within the next 100 hours TIS after the effective 
date of this AD, whichever occurs later, replace the main wing 
attachment and wing spar root pins and modify the corresponding 
area. Accomplish these actions in accordance with the WORK PROCEDURE 
section of Mandatory Bulletin Number L33/008a, dated January 20, 
1998.

    Note 2: When shipping the parts required to accomplish the 
actions of this AD, LET Aeronautical Works will also send a service 
technician to train or assist mechanics within the geographic 
locations of the Model L33 SOLO sailplane owners.

    (b) As of the effective date of this AD, no person may install, 
on any of the affected sailplanes, main wing attachments or wing 
spar root pins without accomplishing the modification specified in 
paragraph (a) of this AD, in accordance with the WORK PROCEDURE 
section of Mandatory Bulletin Number L33/008a, dated January 20, 
1998.
    (c) 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 sailplane to a location where 
the requirements of this AD can be accomplished.
    (d) An alternative method of compliance or adjustment of the 
compliance time that provides an equivalent level of safety may be 
approved by the Manager, Small Airplane Directorate, FAA, 1201 
Walnut, suite 900, Kansas City, Missouri 64106. The request shall be 
forwarded through an appropriate FAA Maintenance Inspector, who may 
add comments and then send it to the Manager, Small Airplane 
Directorate.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Small Airplane Directorate.

    (e) Questions or technical information related to LET Mandatory 
Bulletin Number L33/008a, dated January 20, 1998 should be directed 
LET Aeronautical Works, 686 04 Kunovice, Czech Republic; telephone: 
+420 632 51 11 11; facsimile: +420 632 613 52. This service 
information may be examined at the FAA, Central Region, Office of 
the Regional Counsel, Room 1558, 601 E. 12th Street, Kansas City, 
Missouri 64106.

    Note 4: The subject of this AD is addressed in Czechoslovakian 
AD CCA-T-AD-1-024/98, dated March 23, 1998.

    Issued in Kansas City, Missouri, on April 7, 1999.
Carolanne L. Cabrini,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-9252 Filed 4-13-99; 8:45 am]
BILLING CODE 4910-13-P