AD 99-14-02

This amendment adopts a new airworthiness directive (AD) that applies to certain LET Aeronautical Works (LET) Model L33 SOLO sailplanes. This AD requires replacing the main wing attachment and wing spar root pins and modifying the corresponding area. This AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for the Czech Republic. The actions specified by this AD are intended 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.

Final rule

99-14-02 LET AERONAUTICAL WORKS: Amendment 39-11210; Docket No. 98-CE-120-AD.
Applicability: The following serial numbers of Model L33 SOLO sailplanes, certificated in any category:

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

960407, 960408, and 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, ifthe 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 assistmechanics 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 mayadd 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 to 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.

(f) The replacements and modification required by this AD shall be done in accordance with LET Mandatory Bulletin Number L33/008a, dated January 20, 1998. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from LET Aeronautical Works, 686 04 Kunovice, Czech Republic. Copies may be inspected at the FAA, Central Region, Office of the Regional Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri, or at the Office of the Federal Register, 800 North Capitol Street, NW, suite 700, Washington, DC.

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

(g) This amendment becomes effective on August 17, 1999.

Events Leading to the Issuance of This AD
A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to certain LET Model L33 SOLO sailplanes was published in the Federal Register as a notice of proposed rulemaking (NPRM) on April 14, 1999 (64 FR 18384). The NPRM proposed to require replacing the main wing attachment and wing spar root pins and modifying the corresponding area. Accomplishment of the proposed actions as specified in the NPRM would be in accordance with LET Mandatory Bulletin Number L33/008a, dated January 20, 1998.

The NPRM was the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for the Czech Republic.

Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were received on the proposed rule or the FAA's determination of the cost to the public.

The FAA's Determination
After careful review of all available information related to the subject presented above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed except for minor editorial corrections. The FAA has determined that these minor corrections will not change the meaning of the AD and will not add any additional burden upon the public than was already proposed.

Cost Impact
The FAA estimates that 20 sailplanes in the U.S. registry will be affected by this AD, that it will take approximately 35 workhours per sailplane to accomplish the required 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 this AD on U.S. operators is estimated to be $60,000, or $3,000 per sailplane.

Regulatory Impact
The regulations adopted herein will 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 final rule does 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) 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 final 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 39Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends 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.

39.13 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive (AD) to read as follows: