AD 98-15-24

This amendment adopts a new airworthiness directive (AD) that applies to certain Stemme GmbH & Co. KG (Stemme) Model S10-V sailplanes. This AD requires replacing the propeller blade suspension forks with parts of improved design. This AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Germany. The actions specified by this AD are intended to prevent propeller suspension fork failure caused by design deficiency, which could result in loss of a propeller blade and loss of sailplane controllability.

Final rule

98-15-24 STEMME GMBH & CO. KG: Amendment 39-10674; Docket No. 97-CE-128-AD.

Applicability: Model S10-V sailplanes (serial numbers (S/N) 14-002 through 14-026, and converted sailplanes S/N 14-003M through 14-063M), certificated in any category.

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 (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 upon the accumulation of 100 hours total time-in-service (TIS) on the sailplane propeller or within the next 10 hours TIS after the effective date of this AD, whichever occurs later, unless already accomplished.

To prevent propeller suspension fork failure caused by design deficiency, which could result in loss of a propeller blade and loss of sailplane controllability, accomplish the following:

(a) Replace the following in accordance with pages 3 and 4 of Stemme GmbH & Co. KG Service Bulletin No. A31-10-020, Am-index: 02.a, dated October 7, 1996:

(1) the propeller blade suspension fork, part number (P/N) 10AP-V08 (or an FAA-approved equivalent P/N), with a new propeller blade suspension fork, P/N A09-10AP-V08 (or an FAA-approved equivalent P/N);

(2) the propeller blade suspension fork distance ring, P/N 10AP-V05 (or an FAA-approved equivalent P/N), with a new propeller fork distance ring, P/N A09-10AP-V05 (or an FAA-approved equivalent P/N); and(3) the propeller blade suspension fork nut, P/N 10AP-V06 (or an FAA-approved equivalent P/N), with a new propeller blade suspension fork nut, P/N A09-10AP-V06 (or an FAA-approved equivalent part number).

(b) 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.

(c) 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 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Small Airplane Directorate.
(d) Questions or technical information related to pages 3 and 4 of Stemme GmbH & Co. KG Service Bulletin No. A31-10-020, Am-index: 02.a, dated October 7, 1996, should be directed to Stemme GmbH & Co. KG, Gustav-Meyer-Allee 25, D-13355 Berlin, Federal Republic of Germany. 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.
(e) The replacements required by this AD shall be done in accordance with pages 3 and 4 of Stemme GmbH & Co. KG Service Bulletin No. A31-10-020, Am-index: 02.a, dated October 7, 1996. 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 Stemme GmbH & Co. KG, Gustav-Meyer-Allee 25, D-13355 Berlin, Federal Republic of Germany. 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 3: The subject of this AD is addressed in German AD 95-177/2, dated January 30, 1997.
(f) This amendment becomes effective on September 15, 1998.

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 on certain Stemme Model S10-V sailplanes was published in the Federal Register as a notice of proposed rulemaking (NPRM) on May 11, 1998 (63 FR 25787). The NPRM proposed to require replacing the propeller blade suspension fork, distance ring, and nut with parts of improved design. Accomplishment of the proposed action as specified in the NPRM would be in accordance with pages 3 and 4 of Stemme GmbH & Co. KG Service Bulletin No. A31-10-020, Am-index: 02.a, dated October 7, 1996.

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

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 thecost 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 7 sailplanes in the U.S. registry will be affected by this AD, that it will take approximately 6 workhours per sailplane to accomplish this action, and that the average labor rate is approximately $60 an hour. Parts cost approximately $930 per sailplane. Based on these figures, the total cost impact of this AD on U.S. operators is estimated to be $9,030, or $1,290 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 Subjectsin 14 CFR Part 39
Air 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: