AD 98-19-01

This amendment adopts a new airworthiness directive (AD) that applies to certain Stemme GmbH & Co. KG (Stemme) Model S10 sailplanes. This AD requires replacing the O-ring that is installed in the mounting part of the pitot tube (in the propeller dome) with one 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 failure of the pitot tube O-ring caused by an ineffective design, which could result in the pitot tube falling out and the sailplane pilot losing airspeed indications.

Final rule; request for comments

98-19-01 STEMME GMBH & CO. KG: Amendment 39-10744; Docket No. 93-CE-24-AD.

Applicability: Model S10 sailplanes, serial numbers 10-01 through 10-35, 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 (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 prior to further flight after the effective date of this AD, unless already accomplished.

To prevent failure of the pitot tube O-ring caused by an ineffective design, which could result in the pitot tube falling out and the sailplane pilot losing airspeed indications, accomplish the following:

(a) Replace the O-ring that is installed in the mounting part of the pitot tube (in the propeller dome) with one of improved design, part number 10 RV-PD28. Accomplish this replacement in accordance with Stemme Technical Bulletin No. A31-10-003, dated February 7, 1992.

NOTE 2: Stemme Technical Bulletin No. A31-10-003, dated February 7, 1992, specifies repetitively greasing the replacement O-ring with silicone at 3-month intervals. This is not a requirement of this AD since it is considered regular maintenance for the sailplane operator.

(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 3: 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 Stemme Technical Bulletin No. A31-10-003, dated February 7, 1992, should be directed to Stemme GmbH & Co. KG, Gustav-Meyer-Allee 25, D-W-1000 Berlin 65, 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 replacement required by this AD shall be done in accordance with Stemme Technical Bulletin No. A31-10-003, dated February 7, 1992. 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-W-1000 Berlin 65, 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 4: The subject of this AD is addressed in German AD 92-197 Stemme, dated April 9, 1992.

(f) This amendment becomes effective on September 25, 1998.

Discussion
The Luftfahrt-Bundesamt (LBA), which is the airworthiness authority for Germany, notified the FAA that an unsafe condition may exist on certain Stemme Model S10 sailplanes. The LBA advises that the original design O-ring that is installed in the mounting part of the pitot tube (in the propeller dome) could fail. The softness of these O-rings makes this part subject to failure due to propeller vibration.

Failure of this O-ring could result in the pitot tube falling out and the sailplane pilot losing airspeed indications.

Relevant Service Information
Stemme has issued Technical Bulletin No. A31-10-003, dated February 7, 1992, which specifies procedures for replacing the O-ring that is installed in the mounting part of the pitot tube (in the propeller dome) with one of improved design

The LBA classified this technical bulletin as mandatory and issued German AD 92-197 Stemme, dated April 9, 1992, in order to assure the continued airworthiness of these sailplanes in Germany.

The FAA's Determination
This sailplane model is manufactured in Germany 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 LBA has kept the FAA informed of the situation described above.

The FAA has examined the findings of the LBA; 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.

Cost Impact
None of the Stemme Model S10 sailplanes affected by this action are on the U.S. Register. All sailplanes included in the applicability of this rule currently are operated by non-U.S. operators under foreign registry; therefore, they are not directly affected by thisAD action. However, the FAA considers this rule necessary to ensure that the unsafe condition is addressed in the event that any of these subject sailplanes are imported and placed on the U.S. Register.

Should an affected sailplane be imported and placed on the U.S. Register, accomplishment of the required modification would take approximately 1 workhour at an average labor charge of $60 per workhour. Parts cost approximately $1 per sailplane. Based on these figures, the total cost impact of this AD would be $61 per sailplane that would become registered in the United States.

The Effective Date of This AD
Since this AD action does not affect any airplane that is currently on the U.S. register, it has no adverse economic impact and imposes no additional burden on any person. Therefore, notice and public procedures hereon are unnecessary and the amendment may be made effective in less than 30 days after publication in the Federal Register.

Comments Invited
Although this action is in the form of a final rule and was not preceded by notice and opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this 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 under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the 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 AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket No. 93-CE-24-AD." The postcard will be date stamped and returned to the commenter.

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) 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, 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: