Document ID: FAA-2021-1010-0001
Agency: faa
Document Type: Proposed Rule
Title: Airworthiness Directives: Stemme AG Gliders
Posted Date: 2021-11-22T05:00Z

[Federal Register Volume 86, Number 222 (Monday, November 22, 2021)]
[Proposed Rules]
[Pages 66229-66231]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-25341]

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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]
RIN 2120-AA64

Airworthiness Directives; Stemme AG Gliders

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain Stemme AG TSA-M Model S6 and S6-RT gliders. This proposed 
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 proposed AD would 
require establishing a life limit of 5 years for certain propeller 
gearbox tooth belts. The FAA is proposing this AD to address the unsafe 
condition on these products.

DATES: The FAA must receive comments on this proposed AD by January 6, 
2022.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:
     Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow the instructions for submitting comments.
     Fax: (202) 493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue SE, Washington, DC 20590.
     Hand Delivery: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    For service information identified in this NPRM, 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: 
[email protected]; 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 (816) 
329-4148.

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 NPRM, the MCAI, 
any comments received, and other information. The street address for 
Docket Operations is listed above.

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; fax: (816) 329-4090; email: 
[email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA invites you to send any written relevant data, views, or 
arguments about this proposal. Send your comments to an address listed 
under ADDRESSES. Include ``Docket No. FAA-2021-1010; Project Identifier 
MCAI-2020-00807-G'' at the beginning of your comments. The most helpful 
comments reference a specific portion of the proposal, explain the 
reason for any recommended change, and include supporting data. The FAA 
will consider all comments received by the closing date and may amend 
this proposal because of those comments.
    Except for Confidential Business Information (CBI) as described in 
the

[[Page 66230]]

following paragraph, and other information as described in 14 CFR 
11.35, the FAA will post all comments received, without change, to 
https://www.regulations.gov, including any personal information you 
provide. The agency will also post a report summarizing each 
substantive verbal contact received about this NPRM.

Confidential Business Information

    CBI is commercial or financial information that is both customarily 
and actually treated as private by its owner. Under the Freedom of 
Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public 
disclosure. If your comments responsive to this NPRM contain commercial 
or financial information that is customarily treated as private, that 
you actually treat as private, and that is relevant or responsive to 
this NPRM, it is important that you clearly designate the submitted 
comments as CBI. Please mark each page of your submission containing 
CBI as ``PROPIN.'' The FAA will treat such marked submissions as 
confidential under the FOIA, and they will not be placed in the public 
docket of this NPRM. Submissions containing CBI should be sent to Jim 
Rutherford, Aviation Safety Engineer, General Aviation & Rotorcraft 
Section, International Validation Branch, FAA, 901 Locust, Room 301, 
Kansas City, MO 64106. Any commentary that the FAA receives which is 
not specifically designated as CBI will be placed in the public docket 
for this rulemaking.

Background

    The European Union Aviation Safety Agency (EASA), which is the 
Technical Agent for the Member States of the European Union, has 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.
    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.

Related Service Information

    The FAA reviewed Stemme Service Bulletin (SB) Doc. No. P062-980049, 
Revision 00, dated May 27, 2020. This SB 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.''

FAA's Determination

    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 is issuing this NPRM 
after determining the unsafe condition described previously is likely 
to exist or develop on other products of the same type design.

Proposed AD Requirements

    This proposed AD would establish a life limit of 5 years for the 
affected propeller gearbox tooth belt.

Differences Between This Proposed AD and the MCAI or Service 
Information

    The MCAI applies to Stemme AG Model ASP S15-1 airplanes, and this 
proposed AD would 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 
proposed AD would not require this inspection because instead, it would 
apply 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 
proposed AD would establish a life limit for the affected propeller 
gearbox tooth belt by requiring that it be removed from service after 5 
years. Operators would be required to record AD compliance each time an 
affected propeller gearbox tooth belt reaches its life limit and is 
replaced.
    Stemme SB Doc. No. P062-980049, Revision 00, dated May 27, 2020, 
requires reporting information to Stemme AG, and this proposed AD would 
not.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 3 gliders of U.S. registry. The FAA estimates that it would 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

[[Page 66231]]

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

    The FAA determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would 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 this proposed 
regulation:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Would not affect intrastate aviation in Alaska, and
    (3) Would 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 Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
1. The authority citation for part 39 continues to read as follows:

    Authority:  49 U.S.C. 106(g), 40113, 44701.

Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive:

Stemme AG: Docket No. FAA-2021-1010; Project Identifier MCAI-2020-
00807-G.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by January 6, 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 or 
email: [email protected].
    (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; fax: (816) 329-4090; email: 
[email protected].
    (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 it in Docket No. FAA-2021-1010.

    Issued on November 15, 2021.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2021-25341 Filed 11-19-21; 8:45 am]
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