[Federal Register Volume 90, Number 189 (Thursday, October 2, 2025)]
[Rules and Regulations]
[Pages 47540-47544]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-19355]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2025-3421; Project Identifier MCAI-2025-01202-G;
Amendment 39-23160; AD 2025-20-07]
RIN 2120-AA64
Airworthiness Directives; Fiberglas-Technik Rudolf Lindner GmbH &
Co. KG (Type Certificate Previously Held by GROB Aircraft AG, Grob
Aerospace GmbH i.l., Grob Aerospace GmbH, Burkhart Grob Luft- und
Raumfahrt GmbH & Co. KG) Gliders
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule; request for comments.
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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all
Fiberglas-Technik Rudolf Lindner GmbH & Co. KG Model G103 TWIN II,
G103A TWIN II ACRO, G103C TWIN III ACRO, and G 103 C TWIN III SL
gliders. This AD was prompted by a report of corrosion on the inner
sides of the welded steel rudder drive plate. This AD requires
repetitive inspections and a one-time detailed inspection of the rudder
drive plate for corrosion and water entry and a modification of the
rudder drive plate to improve corrosion protection, as applicable. This
AD also requires replacement of the rudder if corrosion is found during
the inspections that exceed light surface rust. This AD also requires
applying additional sealing to the rudder drive plate, which
constitutes terminating action for the repetitive inspections. The
[[Page 47541]]
FAA is issuing this AD to address the unsafe condition on these
products.
DATES: This AD is effective October 17, 2025.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of October 17,
2025.
The FAA must receive comments on this AD by November 17, 2025.
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 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.
AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2025-3421; 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 mandatory continuing airworthiness
information (MCAI), any comments received, and other information. The
street address for Docket Operations is listed above.
Material Incorporated by Reference:
For Fiberglas-Technik Rudolf Lindner material identified
in this AD, contact Fiberglas-Technik Rudolf Lindner GmbH & Co. KG,
Steige 3 Walpertshofen, Germany; phone: +49 (0) 7353 22 43; email:
Lindner.com">info@LTB-Lindner.com; website: ltb-lindner.com.
You may view this material 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 regulations.gov under
Docket No. FAA-2025-3421.
FOR FURTHER INFORMATION CONTACT: Adam Hein, Aviation Safety Engineer,
FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (316)
946-4116; email: [email protected].
SUPPLEMENTARY INFORMATION:
Comments Invited
The FAA invites you to send any written data, views, or arguments
about this final rule. Send your comments using a method listed under
the ADDRESSES section. Include ``Docket No. FAA-2025-3421; Project
Identifier MCAI-2025-01202-G'' at the beginning of your comments. The
most helpful comments reference a specific portion of the final rule,
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 final rule because of those comments.
Except for Confidential Business Information (CBI) as described in
the following paragraph, and other information as described in 14 CFR
11.35, the FAA will post all comments received, without change, to
regulations.gov, including any personal information you provide. The
agency will also post a report summarizing each substantive verbal
contact received about this final rule.
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 AD 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 AD, 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 AD. Submissions containing CBI should be sent to Adam
Hein, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410,
Westbury, NY 11590. 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 2025-0140, dated July 7, 2025 (referred to as ``the MCAI''), to
correct an unsafe condition on all Fiberglas-Technik Rudolf Lindner
GmbH & Co. KG Model G103 TWIN II, G103A TWIN II ACRO, G103C TWIN III,
G103C TWIN III ACRO, and G 103 C TWIN III SL sailplanes (gliders).
The MCAI states that corrosion was found on the inner sides of the
welded drive plate during a teardown inspection of a rudder. This
condition, if not detected and corrected, could affect the structural
integrity of the rudder drive plate, which could lead to reduced
control or loss of control of the glider. The MCAI requires repetitive
inspections of the rudder drive plate for corrosion and possible water
entry and a one-time detailed inspection and modification of the rudder
drive plate either immediately or at the next service life extension
inspection, depending on the results of the inspection. The MCAI also
requires replacement of the rudder assembly if corrosion is found
during the inspections that exceed light surface rust. The MCAI also
requires applying additional sealing to the rudder drive plate, which
constitutes terminating action for the repetitive inspections.
You may examine the MCAI in the AD docket at regulations.gov under
Docket No. FAA-2025-3421.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed Fiberglas-Technik Rudolf Lindner Service Bulletin
SB-G10, Revision 1, dated February 27, 2025. This material specifies
procedures for inspecting the rudder drive plate for corrosion and
water entry, modifying the rudder drive plate to improve corrosion
protection, applying additional sealing, and replacing the rudder. This
material contains German to English translation.
The European Union Aviation Safety Agency (EASA) used the English
translation in referencing the document. For enforceability purposes,
the FAA will refer to the Fiberglas-Technik Rudolf Lindner service
material in English as it appears on the document.
This material 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.
FAA's Determination
These products have been approved by the civil aviation authority
of another country and are approved for operation in the United States.
Pursuant to the FAA's bilateral agreement with this State of Design
Authority, that authority has notified the FAA of the unsafe condition
described in the MCAI referenced above. The FAA is issuing this AD
after determining that the unsafe condition described previously is
likely to exist or develop on other products of the same type design.
AD Requirements
This AD requires accomplishing the actions specified in the
material already described, except as discussed under ``Differences
Between this AD and the Service Material and MCAI.''
[[Page 47542]]
Differences Between This AD and the Service Material and MCAI
While the MCAI applies to Fiberglas-Technik Rudolf Lindner GmbH &
Co. KG Model G103C TWIN III gliders, this AD does not because this
model does not have an FAA type certificate.
Fiberglas-Technik Rudolf Lindner Service Bulletin SB-G10, Revision
1, dated February 27, 2025, requires replacing the rudder or contacting
the manufacturer for approved instructions if corrosion exceeding light
surface rust is detected. This AD requires replacing the rudder or
contacting either the Manager, International Validation Branch, FAA; or
EASA; or Fiberglas-Technik Rudolf Lindner GmbH & Co. KG's EASA Design
Organization Approval (DOA) for approved instructions if corrosion
exceeding light surface rust is detected. If approved by the DOA, the
approval must include the DOA-authorized signature.
Justification for Immediate Adoption and Determination of the Effective
Date
Section 553(b) of the Administrative Procedure Act (APA) (5 U.S.C.
551 et seq.) authorizes agencies to dispense with notice and comment
procedures for rules when the agency, for ``good cause,'' finds that
those procedures are ``impracticable, unnecessary, or contrary to the
public interest.'' Under this section, an agency, upon finding good
cause, may issue a final rule without providing notice and seeking
comment prior to issuance. Further, section 553(d) of the APA
authorizes agencies to make rules effective in less than thirty days,
upon a finding of good cause.
An unsafe condition exists that requires the immediate adoption of
this AD without providing an opportunity for public comments prior to
adoption. The FAA has found that the risk to the flying public
justifies forgoing notice and comment prior to adoption of this rule
because corrosion on the inner sides of the welded steel rudder drive
plate could affect the structural integrity of the rudder drive plate
and lead to reduced control or loss of control of the glider.
Additionally, the glider fleet has an average age of 5,400 flight
hours, and due to limitations in general aviation reporting, the exact
age of each glider is unknown. Based on the fleet's age distribution
and an average of 10 hours time-in-service (TIS) per month, it is
estimated that certain gliders will require the one-time inspection and
modification within 50 hours TIS or 3 months, whichever occurs first,
which is shorter than the time necessary for the public to comment and
for publication of the final rule. Accordingly, notice and opportunity
for prior public comment are impracticable and contrary to the public
interest pursuant to 5 U.S.C. 553(b).
In addition, the FAA finds that good cause exists pursuant to 5
U.S.C. 553(d) for making this amendment effective in less than 30 days,
for the same reasons the FAA found good cause to forgo notice and
comment.
Regulatory Flexibility Act
The requirements of the Regulatory Flexibility Act (RFA) do not
apply when an agency finds good cause pursuant to 5 U.S.C. 553 to adopt
a rule without prior notice and comment. Because the FAA has determined
that it has good cause to adopt this rule without prior notice and
comment, RFA analysis is not required.
Costs of Compliance
The FAA estimates that this AD affects 68 gliders of U.S. registry.
The FAA estimates the following costs to comply with this AD:
Estimated Costs
----------------------------------------------------------------------------------------------------------------
Parts Cost on U.S.
Action Labor cost cost Cost per product operators
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Inspect rudder drive plate........ 1 work-hour x $85 per $0 $85 per inspection $5,780 per inspection
hour = $85 per cycle. cycle.
inspection cycle.
Detailed inspection of rudder 4 work-hours x $85 0 $340................. $23,120.
drive plate. per hour = $340.
Apply sealing..................... 1 work-hour x $85 per 0 $85.................. $5,780.
hour = $85.
Re-install rudder................. 1 work-hour x $85 per 0 $85.................. $5,780.
hour = $85.
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The FAA estimates the following costs to do any necessary
modification or replacement of the rudder that would be required based
on the results of the inspection. The agency has no way of determining
the number of gliders that might need the modification or replacement.
On-Condition Costs
----------------------------------------------------------------------------------------------------------------
Cost per
Action Labor cost Parts cost product
----------------------------------------------------------------------------------------------------------------
Replace rudder................................ 2 work-hours x $85 per hour = $6,582 $6,752
$170.
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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
[[Page 47543]]
responsibilities among the various levels of government.
For the reasons discussed above, I certify that this AD:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866, and
(2) Will not affect intrastate aviation in Alaska.
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
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:
2025-20-07 Fiberglas-Technik Rudolf Lindner GmbH & Co. KG (type
certificate previously held by GROB Aircraft AG, Grob Aerospace GmbH
i.l., Grob Aerospace GmbH, Burkhart Grob Luft- und Raumfahrt GmbH &
Co. KG): Amendment 39-23160; Docket No. FAA-2025-3421; Project
Identifier MCAI-2025-01202-G.
(a) Effective Date
This airworthiness directive (AD) is effective October 17, 2025.
(b) Affected ADs
None.
(c) Applicability
This AD applies to Fiberglas-Technik Rudolf Lindner GmbH & Co.
KG (type certificate previously held by GROB Aircraft AG, Grob
Aerospace GmbH i.l., Grob Aerospace GmbH, Burkhart Grob Luft- und
Raumfahrt GmbH & Co. KG) Model G103 TWIN II, G103A TWIN II ACRO,
G103C TWIN III ACRO, and G 103 C TWIN III SL gliders, certificated
in any category.
(d) Subject
Joint Aircraft System Component (JASC) Code 2720, Rudder Control
System.
(e) Unsafe Condition
This AD was prompted by a report of corrosion on the inner sides
of the welded steel rudder drive plate. The FAA is issuing this AD
to detect and address corrosion and water entry in the rudder drive
plate. The unsafe condition, if not detected and corrected, could
affect the structural integrity of the rudder drive plate, which
could lead to reduced control or loss of control of the glider.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Definition
For the purpose of this AD, a ``serviceable rudder'' is a rudder
which has accumulated zero hours time-in-service (TIS), or a rudder
that has been inspected and modified, as necessary, in accordance
with paragraphs (h)(1) and (2) of this AD and is found to be crack
and corrosion free.
(h) Required Actions
(1) Within 50 hours TIS or 3 months, whichever occurs first
after the effective date of this AD, and, thereafter, at intervals
not to exceed every 12 months, inspect the rudder drive plate for
evidence of corrosion or water entry in accordance with the Actions
and Instructions, section A, of Fiberglas-Technik Rudolf Lindner
Service Bulletin SB-G10, Revision 1, dated February 27, 2025.
(2) Perform a one-time detailed inspection of the rudder drive
plate in accordance with the Actions and Instructions, section B,
steps 1 and 2 of Fiberglas-Technik Rudolf Lindner Service Bulletin
SB-G10, Revision 1, dated February 27, 2025, at whichever compliance
time in paragraphs (h)(2)(i) or (ii) of this AD occurs first.
(i) Before further flight if during any inspection as required
by paragraph (h)(1) of this AD, evidence of corrosion or water
ingress is found; or
(ii) At the next service life extension inspection that occurs
after the effective date of this AD.
(3) If, as a result of the inspection required by paragraph
(h)(2) of this AD, corrosion of the rudder drive plate is detected
that exceeds light surface rust and cannot be removed using steel
wool, before further flight, replace the rudder with a serviceable
rudder, or contact the Manager, International Validation Branch,
FAA; or EASA; or Fiberglas-Technik Rudolf Lindner GmbH & Co. KG EASA
Design Organization Approval (DOA) for approved instructions. If
approved by the DOA, the approval must include the DOA-authorized
signature.
(4) If the rudder is replaced with a serviceable rudder, before
further flight, apply additional sealing to the rudder drive plate
in accordance with the Actions and Instructions, Section C, of
Fiberglas-Technik Rudolf Lindner Service Bulletin SB-G10, Revision
1, dated February 27, 2025.
(5) If, as a result of the inspection required by paragraph
(h)(2) of this AD, light surface rust is detected, before further
flight, modify the rudder drive plate in accordance with the Actions
and Instructions, section B, steps 4 through 7 of Fiberglas-Technik
Rudolf Lindner Service Bulletin SB-G10, Revision 1, dated February
27, 2025.
(6) If, as a result of the inspection required by paragraph
(h)(2) of this AD, no evidence of corrosion or water ingress is
detected, before further flight, modify the rudder drive plate in
accordance with the Actions and Instructions, section B, steps 5
through 7 of Fiberglas-Technik Rudolf Lindner Service Bulletin SB-
G10, Revision 1, dated February 27, 2025.
(7) Following completion of the modification of the rudder drive
plate required by paragraph (h)(5) or (h)(6) of this AD, before
further flight, apply additional sealing to the rudder drive plate
in accordance with the Actions and Instructions, Section C, of
Fiberglas-Technik Rudolf Lindner Service Bulletin SB-G10, Revision
1, dated February 27, 2025.
(8) Following completion of the sealing application required by
paragraph (h)(7) of this AD, re-install the rudder in accordance
with the Actions and Instructions, Section D, of Fiberglas-Technik
Rudolf Lindner Service Bulletin SB-G10, Revision 1, dated February
27, 2025.
(9) Application of additional sealing to the rudder drive plate,
as required by paragraphs (h)(4) and (h)(7) of this AD, constitutes
terminating action for the repetitive inspections required by
paragraph (h)(1) of this AD for that glider.
(i) Alternative Methods of Compliance (AMOCs)
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 International Validation Branch, send
it to the attention of the person identified in paragraph (j) of
this AD and email to [email protected]. 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.
(j) Additional Information
For more information about this AD, contact Adam Hein, Aviation
Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY
11590; phone: (316) 946-4116; email: [email protected].
(k) Material Incorporated by Reference
(1) The Director of the Federal Register approved the
incorporation by reference (IBR) of the material listed in this
paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
(2) You must use this material as applicable to do the actions
required by this AD, unless the AD specifies otherwise.
(i) Fiberglas-Technik Rudolf Lindner Service Bulletin SB-G10,
Revision 1, dated February 27, 2025.
Note 1 to paragraph (k)(2)(i): This material contains German to
English translation. The European Union Aviation Safety Agency
(EASA) used the English translation in referencing the document. For
enforceability purposes, the FAA will refer to the Fiberglas-Technik
Rudolf Lindner service material in English as it appears on the
document.
(ii) [Reserved]
(3) For Fiberglas-Technik Rudolf Lindner material identified in
this AD, contact Fiberglas-Technik Rudolf Lindner GmbH & Co. KG,
Steige 3 Walpertshofen, Germany;
[[Page 47544]]
phone: +49 (0) 7353 22 43; email: Lindner.com">info@LTB-Lindner.com; website:
ltb-lindner.com.
(4) You may view this material 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.
(5) You may view this material at the National Archives and
Records Administration (NARA). For information on the availability
of this material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email [email protected].
Issued on September 30, 2025.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2025-19355 Filed 9-30-25; 4:15 pm]
BILLING CODE 4910-13-P