DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2017-0952; Product Identifier 2017-CE-028-AD; Amendment
39-19189; AD 2018-03-16]
Airworthiness Directives; Stemme AG Gliders
AGENCY: Federal Aviation Administration (FAA), Department of
ACTION: Final rule.
SUMMARY: We are superseding Airworthiness Directive (AD) 2017-10-11
Stemme AG Model Stemme S10-VT gliders (type certificate previously held
by Stemme GmbH & Co. KG). This AD results from mandatory continuing
airworthiness information (MCAI) issued by an aviation authority of
another country to identify and address an unsafe condition on an
aviation product. The MCAI describes the unsafe condition as certain
propeller front transmission gear wheels having insufficient material
strength because of improper heat treatment during manufacturing. We
are issuing this AD to require actions to address the unsafe condition
on these products and to add Stemme AG Model Stemme S 12 gliders to the
DATES: This AD is effective March 20, 2018.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of March 20,
ADDRESSES: You may examine the AD docket on the internet at http://www.
regulations.gov by searching for and locating Docket No. FAA-2017-
0952; or in person at Docket Operations, U.S. Department of
Transportation, M-30, West Building Ground Floor, Room W12-140, 1200
New Jersey Avenue SE, Washington, DC 20590.
For service information identified in this AD, contact STEMME AG,
Flugplatzstrasse F2, Nr. 6-7, D-15344 Strausberg, Germany; telephone:
+49 (0) 3341 3612-0, fax: +49 (0) 3341 3612-30; internet: https://www.
stemme.com. You may view this referenced service information at the
FAA, Policy and Innovation Division, 901 Locust, Kansas City, Missouri
64106. For information on the availability of this material at the FAA,
call (816) 329-4148. It is also available on the internet at http://www.
regulations.gov by searching for Docket No. FAA-2017-0952.
FOR FURTHER INFORMATION CONTACT: Jim Rutherford, Aerospace Engineer,
FAA, Small Airplane Standards Branch, 901 Locust, Room 301, Kansas
City, Missouri 64106; telephone: (816) 329-4165; fax: (816) 329-4090;
We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR
part 39 by adding an AD that would apply to all Stemme AG Model Stemme
S10-VT gliders (type certificate previously held by Stemme GmbH & Co.
KG) and all Stemme AG Model Stemme S 12 gliders equipped with a certain
front gearbox, part number 11AG. That NPRM was published in the Federal
Register on October 10, 2017 (82 FR 46938), and proposed to supersede
AD 2017-10-11, Amendment 39-18885 (82 FR 24239, May 26, 2017) (``AD
Since we issued AD 2017-10-11, we have type certificated Stemme AG
Model Stemme S 12 gliders in the United States and have determined
those model gliders should also be included in the applicability of AD
2017-10-11. In addition, Stemme AG has issued new service information
with procedures for addressing the unsafe condition.
We gave the public the opportunity to participate in developing
this AD. The following presents the comment received on the proposal
and the FAA's response to the comment.
Request for Manufacturer To Be Responsible for All Associated Cost
Taylor Ray stated that the manufacturer should be responsible for
replacing the front gearbox on the affected gliders at no cost to the
owners/operators. We infer that the commenter is referring to the cost
for both parts and labor.
Taylor Ray stated that since the unsafe condition resulted from the
manufacturing process, the manufacturer should be responsible for
fixing the unsafe condition.
We neither agree nor disagree since the FAA does not get involved
in who pays for the cost of mitigating an unsafe condition. The primary
concern the FAA has when issuing an AD is addressing unsafe conditions
on various aircraft flying in the United States. While we provide
information related to the estimated labor and parts cost associated
with each AD, we do not control warranty coverage for owner/operators
of the affected aircraft nor can
we mandate the manufacturer to cover all associated costs. We have
contacted Stemme AG about this issue. The following is the response we
received: ``All costs will be paid by Stemme AG (parts + work) for
customers who are affected within the one-year warranty. Customers who
are out of the one-year warranty will receive parts for free, but
unfortunately, they have to pay for the necessary work (approx. 10
working hours).'' Based on this response from Stemme AG, we revised the
Cost of Compliance section in this AD. We changed the number of
estimated work-hours per product to replace the front gearbox from 19
to 10, updated the total cost on U.S. operators and cost per product
based on this change, and added standard warranty information.
We reviewed the relevant data, considered the comment received, and
determined that air safety and the public interest require adopting
this AD as proposed except for changes stated above. We have determined
that these changes:
Are consistent with the intent that was proposed in the
NPRM for addressing the unsafe condition; and
Do not add any additional burden upon the public than was
already proposed in the NPRM.
Related Service Information Under 1 CFR Part 51
Stemme AG has issued STEMME Service Bulletin Dok. Nr.: P062-980010,
Issue: 01, dated June 14, 2017, and STEMME Procedural Specification
Dok. Nr.: P320-900060, dated June 14, 2017. In combination, the service
information describes procedures for replacing the front gearbox. This
service information is reasonably available because the interested
parties have access to it through their normal course of business or by
the means identified in the ADDRESSES section of this AD.
Differences Between This AD and the Service Information
The service information for this AD allows the owner/operator to do
certain maintenance tasks. Also, the service information specifies
certain maintenance tasks be done by Stemme AG. However, for this AD,
we do not allow the owner/operator to do any maintenance tasks; all
maintenance tasks must be done by an appropriately certified mechanic
or maintenance shop. In addition, we do not require any maintenance
tasks be done specifically by Stemme AG; any appropriately certified
mechanic or maintenance shop may do the tasks required by this AD.
Costs of Compliance
According to the U.S. registry, we have a total of 51 of both
glider types registered, but there are still only 14 serial numbers of
the part number 11AG front gearbox. Therefore, the most gliders that
will be affected remains 14. According to Stemme AG, there are a total
of 4 of the affected front gearboxes on both glider types of U.S.
registry (2 for each model).
It will take an estimated 10 work-hours per product to comply with
the basic requirements of this AD. The average labor rate is $85 per
work-hour. Required parts will cost about $2,000 per product.
Based on these figures, if we consider the costs for all 14
affected gearboxes, then we estimate the cost of this AD on U.S.
operators to be $39,990, or $2,850 per product.
According to the manufacturer, some of the costs of this AD may be
covered under warranty, thereby reducing the cost impact on affected
individuals. We do not control warranty coverage for affected
individuals. As a result, we have included all costs in our cost
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
We are 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
This AD is issued in accordance with authority delegated by the
Executive Director, Aircraft Certification Service, as authorized by
FAA Order 8000.51C. In accordance with that order, issuance of ADs is
normally a function of the Compliance and Airworthiness Division, but
during this transition period, the Executive Director has delegated the
authority to issue ADs applicable to small airplanes, gliders,
balloons, airships, domestic business jet transport airplanes, and
associated appliances to the Director of the Policy and Innovation
We determined that 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 this AD:
(1) Is not a ``significant regulatory action'' under Executive
(2) Is not a ``significant rule'' under the DOT Regulatory Policies
and Procedures (44 FR 11034, February 26, 1979),
(3) Will not affect intrastate aviation in Alaska, and
(4) 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.
Examining the AD Docket
You may examine the AD docket on the internet at http://www.regulations.
gov by searching for and locating Docket No. FAA-2017-
0952; or in person at Docket Operations between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays. The AD docket contains
the NPRM, the regulatory evaluation, any comments received, and other
information. The street address for Docket Operations (telephone (800)
647-5527) is in the ADDRESSES section. Comments will be available in
the AD docket shortly after receipt.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
Adoption of 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.
Sec. 39.13 [Amended]
2. The FAA amends Sec. 39.13 by removing Amendment 39-18885 (82 FR
24239, May 26, 2017), and adding the following new AD: