00-18597. Airworthiness Directives; Stemme GmbH & Co. KG Models S10-V and S10-VT Sailplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Final rule; request for comments.

SUMMARY:

This amendment adopts a new airworthiness directive (AD) that applies to Stemme GmbH & Co. KG (Stemme) Models S10-V and S10-VT sailplanes. This AD supersedes AD 98-15-24, which currently requires replacing the propeller blade suspension forks with parts of improved design on Stemme S10-V sailplanes. This AD requires you to remove the propeller blade suspension forks, exchange them with the manufacturer for improved design forks, and install the improved design propeller blade suspension forks. This AD is the result of analysis that shows that the existing propeller blade suspension forks are currently cracking more rapidly than originally projected. The actions specified by this AD are intended to prevent certain propeller blade suspension forks from cracking, which could result in the loss of a propeller blade during flight with possible lateral imbalance and loss of thrust.

DATES:

This AD becomes effective on August 4, 2000.

The Director of the Federal Register approved the incorporation by reference of certain publications listed in the regulation as of August 4, 2000.

The Federal Aviation Administration (FAA) must receive any comments on this rule on or before August 25, 2000.

ADDRESSES:

Submit comments in triplicate to the FAA, Central Region, Office of the Regional Counsel, Attention: Rules Docket No. 99-CE-25-AD, 901 Locust, Room 506, Kansas City, Missouri 64106.

You may get the service information referenced in this AD from Stemme GmbH & Co. KG, Gustav-Meyer-Allee 25, D-13355 Berlin, Germany; telephone: [phone]; facsimile: 49.33.41.31.11.73.

You may examine this information at FAA, Central Region, Office of the Regional Counsel, Attention: Rules Docket No. 99-CE-25-AD, 901 Locust, Room 506, Kansas City, Missouri 64106; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT:

Mr. Mike Kiesov, Aerospace Engineer, FAA, Small Airplane Directorate, 1201 Walnut, suite 900, Kansas City, Missouri 64106; telephone: [phone]; facsimile: [phone].

SUPPLEMENTARY INFORMATION:

Events Leading to the Issuance of This AD

Has FAA taken any action to this point? An incident where the propeller blade suspension fork failed during flight on a Stemme Model S10-V sailplane caused FAA to issue AD 98-15-24, Amendment 39-10674. This AD was published in the Federal Register on July 23, 1998 (63 FR 39484), and required replacing the propeller blade suspension fork, distance ring, and nut with parts of improved design on Stemme Model S10-V sailplanes.

After issuing AD 98-15-24, the Luftfahrt-Bundesamt (LBA), which is the airworthiness authority for Germany, notified FAA that the improved design propeller blade suspension fork (part number (P/N) A09-10AP-V08) on one of the affected sailplanes failed during flight. Analysis of this propeller blade revealed a fracture located at the end of the threaded fastening pin. This caused FAA to issue a proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to all Stemme Models S10-V and S10-VT sailplanes that incorporate a certain propeller blade suspension fork. This proposal was published in the Federal Register as a notice of proposed rulemaking (NPRM) on July 21, 1999 (64 FR 39100).

The NPRM proposed to supersede AD 98-15-24 with a new AD that would require you to repetitively exchange (through the manufacturer) the P/N A09-10AP-V08 (or FAA-approved equivalent part number) propeller blade suspension fork for a fork that has passed X-ray crack testing requirements.

Was the public invited to comment on the NPRM? The FAA invited interested persons to participate in the making of the amendment. We received no comments on the proposed rule or the cost impact upon the public. However, the LBA has informed us that the existing propeller blade suspension forks are currently cracking more rapidly than originally projected.

Is there a propeller blade suspension fork design that is better than the current design? Stemme has worked with the LBA in designing an improved propeller blade suspension fork (P/N 10AP-V88) along with a modification to the propeller gearbox suspension.

Has the manufacturer issued service information? Stemme issued Service Bulletin No. A31-10-051, Amendment-Index 05.a, dated December 6, 1999. This service bulletin specifies procedures for accomplishing the propeller blade suspension fork replacement and propeller gearbox suspension modification, which were described previously.

The FAA's Determination and Followup Action

What have we decided? After careful review of all available information related to the subject presented above, including the above-referenced comments, FAA has determined that:

—the propeller blade suspension fork replacement and propeller gearbox suspension modification should be accomplished on all Stemme Models S10-V and S10-VT sailplanes; and

—AD action should be taken to prevent certain propeller blade suspension forks from cracking, which could result in the loss of a propeller blade during flight with possible lateral imbalance and loss of thrust.

What is our next action? Since the improved design propeller blade suspension fork replacement and propeller gearbox suspension modification requirements increase the burden on the owners/operators of the affected sailplanes over what was proposed in the NPRM, we are required to allow the public additional time to comment on the AD.

Because of the low hours TIS on the sailplanes where the cracked propeller blade suspension forks were found, FAA finds that notice and opportunity for public prior comment are impracticable. Therefore, good cause exists for making this amendment effective in less than 30 days.

What does this AD require? This AD requires you to:

—remove the propeller blade suspension forks;

—exchange them with the manufacturer for improved design forks; and

—install the improved design propeller blade suspension forks.

Accomplishment procedures are specified in Stemme Service Bulletin No. A31-10-051, Amendment-Index 05.a, dated December 6, 1999.

Comments Invited

Can I comment on this AD? This action is in the form of a final rule and the FAA did not precede it with notice and opportunity for public comment. FAA is issuing this final rule without prior notice because an urgent situation concerning safety of flight exists. However, FAA is still inviting comments on this rule. You may submit whatever written data, views, or arguments you choose. You need to include the rule's docket number and submit your comments in triplicate to the address specified under the caption ADDRESSES. The FAA will consider all comments received on or before the closing date. We may amend this rule in light of comments received.

How can we communicate more clearly with you? The FAA is reviewing the writing style we currently use in regulatory documents, in response to the Presidential memorandum of June 1, 1998. That memorandum requires federal agencies to communicate more clearly with the public. We are interested in your comments on the ease of understanding this document, and any other suggestions you might have to improve the clarity of FAA communications that affect you. You can get more information about the Presidential memorandum and the plain language initiative at http://www.faa.gov/​language/​.

The FAA specifically invites comments on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. You may examine all comments we receive before and after the closing date of the rule in the Rules Docket. We will file a report in the Rules Docket that summarizes each FAA contact with the public that concerns the substantive parts of this AD.

How can I be sure the FAA receives my comment? If you want us to acknowledge the receipt of your comments, you must include a self-addressed, stamped postcard. On the postcard, write “Comments to Docket No. 99-CE-25-AD.” We will date stamp and mail the postcard back to you.

Regulatory Impact

How does this AD impact relations between Federal and State governments? These regulations will not have a substantial direct effect 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. The FAA has determined that this final rule does not have federalism implications under Executive Order 13132.

How does this action involve an emergency situation? The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and is not a significant regulatory action under Executive Order 12866. We have determined that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If FAA determines that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, we will prepare a final regulatory evaluation. You may obtain a copy of the evaluation (if required) from the Rules Docket.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Incorporation by reference
• Safety

Adoption of the Amendment

Accordingly, under 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. FAA amends section 39.13 by removing Airworthiness Directive (AD) 98-15-24, Amendment 39-10674 (39484, July 23, 1998), and by adding a new AD to read as follows:

2000-15-03 Stemme GmbH & Co. KG: Amendment 39-11832; Docket No. 99-CE-25-AD.

(a) What sailplanes are affected by this AD? This AD applies to Models S10-V and S10-VT sailplanes, all serial numbers, certificated in any category.

(b) Who must comply with this AD? Anyone who wishes to operate any of the above sailplanes on the U.S. Register must comply with this AD.

(c) What problem does this AD address? The actions of this AD are intended to prevent certain propeller blade suspension forks from cracking, which could result in the loss of a propeller blade during flight with possible lateral imbalance and loss of thrust.

(d) What actions must I accomplish to address this problem? To address this problem, you must accomplish the following:

Action	When	Procedures
(1) Removal, exchange, and reinstallation:	All actions within 10 hours time-in-service as (TIS) after August 4, 2000 (the effective date of this AD)	(1) Accomplish, each action accordingly, as follows:
(i) Remove from the sailplane any propeller blade suspension fork that is not part number (P/N) 10AP-V88		(i) Removal: In accordance with the instructions in the maintenance manual.
(ii) Exchange (through the manufacturer) this propeller blade suspension fork for a propeller blade suspension fork that is P/N 10AP-V88.		(ii) Exchange: In accordance with the instructions in Stemme Service Bulletin No. A31-10-051, Amendment-Index: 05.a, dated December 6, 1999.
(iii) Install the improved design propeller blade suspension fork (P/N 10AP-V88) on the sailplane.		(iii) Installation: In accordance with the instructions in the maintenance manual.
(2) Modify the propeller gearbox suspension.	Within 10 hours TIS after August 4, 2000 (the effective date of this AD).	In accordance with the instructions in Stemme Service Bulletin No. A31-10-051, Amendment-Index: 05.a, dated December 6, 1999.
(3) Dynamically balance the propeller.	Prior to further flight after the installation and modification required in paragraphs (d)(1)(i), (d)(1)(ii), (d)(1)(iii), and (d)(2) of this AD.	In accordance with the instructions in Stemme Procedural Instruction A17-10AP-V/2-E “Dynamic balancing of the Stemme S10 powered glider propeller in the S10-V and S10-VT models.”
(4) Do not install a propeller blade suspension fork that is not P/N 10AP-V88 on any affected sailplane	As of August 4, 2000 (the effective date of this AD)	Not Applicable.

(e) Can I comply with this AD in any other way?

(1) You may use an alternative method of compliance or adjust the compliance time if:

(i) Your alternative method of compliance provides an equivalent level of safety; and

(ii) The Manager, Small Airplane Directorate, approves your alternative. Submit your request through an FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Small Airplane Directorate.

(2) Alternative methods of compliance that were approved in accordance with AD 98-15-24 are not considered approved in accordance with this AD.

Note:

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 (e) 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 you have not eliminated the unsafe condition, specific actions you propose to address it.

(f) Where can I get information about any already-approved alternative methods of compliance? Contact Mike Kiesov, Aerospace Engineer, FAA, Small Airplane Directorate, 1201 Walnut, suite 900, Kansas City, Missouri 64106; telephone: [phone]; facsimile: [phone].

(g) What if I need to fly the sailplane to another location to comply with this AD? The FAA can issue a special flight permit under sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate your sailplane to a location where you can accomplish the requirements of this AD.

(h) Are any service bulletins incorporated into this AD by reference?

(1) Actions required by this AD must be done as follows:

(i) Modification: In accordance with Stemme Service Bulletin No. A31-10-051, Amendment-Index: 05.a, dated December 6, 1999; and

(ii) Balancing: In accordance with Stemme Procedural Instruction A17-10AP-V/2-E “Dynamic balancing of the Stemme S10 powered glider propeller in the S10-V and S10-VT models”, August 24, 1999.

(2) The Director of the Federal Register approved this incorporation by reference under 5 U.S.C. 552(a) and 1 CFR part 51.

(3) You can get copies from Stemme GmbH & Co. KG, Gustav-Meyer-Allee 25, D-13355 Berlin, Germany; telephone: [phone]; facsimile: 49.33.41.31.11.73.

(4) You can look at copies at FAA, Central Region, Office of the Regional Counsel, 901 Locust, Room 506, Kansas City, Missouri; or at the Office of the Federal Register, 800 North Capitol Street, NW, suite 700, Washington, DC.

(i) When does this amendment become effective? This amendment becomes effective on August 4, 2000.

Issued in Kansas City, Missouri, on July 17, 2000.

Marvin R. Nuss,

Acting Manager, Small Airplane Directorate, Aircraft Certification Service.