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###### Department of Transportation

###### Federal Aviation Administration

          - 14 CFR Part 39
          - [Docket No. FAA-2021-1010; Project Identifier MCAI-2020-00807-G; Amendment 39-21924; AD 2022-03-07]
          - RIN 2120-AA64

# AGENCY:

Federal Aviation Administration (FAA), DOT.

# ACTION:

Final rule.

# SUMMARY:

The FAA is adopting a new airworthiness directive (AD) for certain Stemme AG TSA-M Model S6 and S6-RT gliders. This AD was prompted by mandatory continuing airworthiness information (MCAI) issued by the aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as a new version of the propeller gearbox tooth belt with a reduced life limit. This AD requires establishing a life limit of 5 years for certain propeller gearbox tooth belts. The FAA is issuing this AD to address the unsafe condition on these products.

# DATES:

This AD is effective March 2, 2022.

# ADDRESSES:

                        For service information identified in this final rule, contact Stemme AG, Flugplatzstrasse F2, Nr. 6-7, D-15344 Strausberg, Germany; phone: +49 (0) 3341 3612-0; fax: +49 (0) 3341 3612-30; email:                         *airworthiness@stemme.de*; website:                         *https://www.stemme.com*. You may view this service information at the FAA, Airworthiness Products Section, Operational Safety Branch, 901 Locust, Kansas City, MO 64106. For information on the availability of this material at the FAA, call (817) 222-5110. It is also available at                         *https://www.regulations.gov*                         by searching for and locating Docket No. FAA-2021-1010.                    

## Examining the AD Docket

                    You may examine the AD docket at                     *https://www.regulations.gov*                     by searching for and locating Docket No. FAA-2021-1010; or in person at Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this final rule, the MCAI, any comments received, and other information. The address for Docket Operations is U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.                

# FOR FURTHER INFORMATION CONTACT:

                        Jim Rutherford, Aviation Safety Engineer, General Aviation & Rotorcraft Section, International Validation Branch, FAA, 901 Locust, Room 301, Kansas City, MO 64106; phone: (816) 329-4165; email:                         *jim.rutherford@faa.gov*.                    

# SUPPLEMENTARY INFORMATION:

## Background

                    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain Stemme AG TSA-M Model S6 and S6-RT gliders. The NPRM published in the                     **Federal Register**                     on November 22, 2021 (86 FR 66229). The NPRM was prompted by MCAI originated by the European Union Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Union. EASA issued EASA AD 2020-0140, dated June 23, 2020 (referred to after this as “the MCAI”), to address an unsafe condition on Stemme AG (Stemme) TSA-M Model S6 and S6-RT powered sailplanes (gliders) and ASP S15-1 airplanes. The MCAI states:                

                        The airworthiness limitations for Stemme TSA-M powered sailplanes and Stemme ASP aeroplanes, which are approved by EASA, are currently defined and published in Chapter 4 of the applicable AMM [aircraft maintenance manual]. These instructions have been identified as mandatory for continued airworthiness.                              ( print page 3927)    

Failure to accomplish these instructions could result in an unsafe condition.

During a regular incoming part inspection at Stemme, the supplier delivered a new version of the tooth belts used in the propeller gearbox. The new part (with marking “Carbon”) deviates from the previously used part (with marking “Extreme”) by its layer build up. The new tooth belt has been found airworthy, although with a reduced life limit.

Before Stemme identified the issue, new tooth belts were delivered, identified as Part Number (P/N) 830.185, the same as the previous part. These parts have to be identified by inspection, changed to P/N 832.502, and the reduced life limit implemented.

Consequently, Stemme issued the applicable ALS [airworthiness limitations section] introducing the new life limit for the new part. Stemme also issued the SB [service bulletin] providing additional instructions on relevant inspections and corrective actions.

For the reasons described above, this [EASA] AD requires a one-time inspection of the propeller gearbox tooth belts, and, depending on findings, re-identification. This [EASA] AD also requires implementation of the reduced life limit by accomplishment of the actions specified in the applicable ALS.

After issuance of the MCAI, EASA approved extending the life limit of the new “Synchroforce Carbon” belt to 5 years, the same as the original “Extreme” belt, as documented by Stemme in Revision 15 to the AMM Chapter 04 ALS.

                    You may examine the MCAI in the AD docket at                     *https://www.regulations.gov*                     by searching for and locating Docket No. FAA-2021-1010.                

## Discussion of Final Airworthiness Directive

## Comments

The FAA received one comment from an individual commenter. The commenter supported the NPRM without change.

## Conclusion

This product has been approved by the aviation authority of another country and is approved for operation in the United States. Pursuant to the FAA's bilateral agreement with this State of Design Authority, it has notified the FAA of the unsafe condition described in the MCAI and service information referenced above. The FAA reviewed the relevant data, considered the comment received, and determined that air safety requires adopting this AD as proposed. Accordingly, the FAA is issuing this AD to address the unsafe condition on these products. This AD is adopted as proposed in the NPRM.

## Related Service Information

The FAA reviewed Stemme Service Bulletin Doc. No. P062-980049, Revision 00, dated May 27, 2020. This service information specifies identifying the front propeller gearbox tooth belt, revising the AMM and illustrated parts catalogue, and introducing a life limit for the propeller gearbox tooth belt marked “Synchroforce Carbon.”

## Differences Between This AD and the MCAI or Service Information

The MCAI applies to Stemme AG Model ASP S15-1 airplanes, and this AD does not because that model does not have an FAA type certificate.

The MCAI requires an inspection to determine whether the propeller gearbox tooth belts are “Synchroforce Carbon” or “Extreme.” This AD does not require this inspection because instead, it applies only to gliders with a “Synchroforce Carbon” propeller gearbox tooth belt installed.

The MCAI requires revising the existing aircraft maintenance program (AMP) to introduce the reduced life limit for the affected propeller gearbox tooth belt, as well as other life limits, as specified in the Temporary Revision to the aircraft maintenance manual airworthiness limitations section (ALS). After the AMP is revised, the MCAI does not require recording AD compliance on a continued basis each time a task in the revised AMP is performed. Because the AMP is not required for U.S. operators and the ALS specified in the MCAI includes additional tasks that do not address the unsafe condition, this AD establishes a life limit for the affected propeller gearbox tooth belt by requiring that it be removed from service after 5 years. Operators are required to record AD compliance each time an affected propeller gearbox tooth belt reaches its life limit and is replaced.

Stemme Service Bulletin Doc. No. P062-980049, Revision 00, dated May 27, 2020, requires reporting information to Stemme AG, and this AD does not.

## Costs of Compliance

The FAA estimates that this AD affects 3 gliders of U.S. registry. The FAA estimates that it will take 4 work hours to replace the propeller gearbox tooth belt and require a part costing $300. The average labor rate is $85 per work hour. Based on these figures, the FAA estimates the cost to replace the propeller gearbox tooth belt on U.S. operators to be $1,920 or $640 per glider, every 5 years.

## Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII: Aviation Programs, describes in more detail the scope of the Agency's authority.

The FAA is issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701: General requirements. Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

## Regulatory Findings

This AD will not have federalism implications under Executive Order 13132. This AD 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. For the reasons discussed above, I certify that this AD. For the reasons discussed above, I certify this AD.

(1) Is not a “significant regulatory action” under Executive Order 12866,

(2) Will not affect intrastate aviation in Alaska, 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.

# List of Subjects in 14 CFR Part 39

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

## The Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 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.

      ( print page 3928)    
§ 39.13 

2. The FAA amends § 39.13 by adding the following new airworthiness directive: 

**2022-03-07 Stemme AG:**                             Amendment 39-21924; Docket No. FAA-2021-1010; Project Identifier MCAI-2020-00807-G.                        

## (a) Effective Date

This airworthiness directive (AD) is effective March 2, 2022.

## (b) Affected ADs

None.

## (c) Applicability

This AD applies to Stemme AG TSA-M Model S6 and S6-RT gliders, all serial numbers, certificated in any category, with a propeller gearbox tooth belt marked “Synchroforce Carbon” installed.

## (d) Subject

Joint Aircraft System Component (JASC) Code 6100, Propeller System.

## (e) Unsafe Condition

This AD was prompted by mandatory continuing airworthiness information (MCAI) issued by the aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as a new version of the propeller gearbox tooth belt with a reduced life limit. The FAA is issuing this AD to prevent a propeller gearbox tooth belt remaining in service beyond its fatigue life. The unsafe condition, if not addressed, could result in failure of the propeller gearbox tooth belt and reduced control of the glider.

## (f) Compliance

Comply with this AD within the compliance times specified, unless already done.

## (g) Required Actions

Before the propeller gearbox tooth belt accumulates 5 years since installation on a glider or within 30 days after the effective date of this AD, whichever occurs later, and thereafter at intervals not to exceed 5 years, remove the propeller gearbox tooth belt from service and install a propeller gearbox tooth belt with zero hours time-in-service.

## (h) Alternative Methods of Compliance (AMOCs)

                            (1) The Manager, International Validation Branch, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the certification office, send it to the attention of the person identified in paragraph (i)(1) of this AD and email to:                             *9-AVS-AIR-730-AMOC@faa.gov*.                        

(2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office.

## (i) Related Information

                            (1) For more information about this AD, contact Jim Rutherford, Aviation Safety Engineer, General Aviation & Rotorcraft Section, International Validation Branch, FAA, 901 Locust, Room 301, Kansas City, MO 64106; phone: (816) 329-4165; email:                             *jim.rutherford@faa.gov*.                        

                            (2) Refer to European Union Aviation Safety Agency (EASA) AD 2020-0140, dated June 23, 2020, for more information. You may examine the EASA AD in the AD docket at                             *https://www.regulations.gov*                             by searching for and locating Docket No. FAA-2021-1010.                        

## (j) Material Incorporated by Reference

None.

Issued on January 20, 2022.

Lance T. Gant,

Director, Compliance & Airworthiness Division, Aircraft Certification Service.

[FR Doc. 2022-01479 Filed 1-25-22; 8:45 am]

BILLING CODE 4910-13-P