Rule2026-06534
Airworthiness Directives; DG Aviation GmbH (Type Certificate Previously Held by DG Flugzeugbau GmbH) Gliders
Primary source
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Published
April 3, 2026
Effective
April 20, 2026
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA is adopting a new airworthiness directive (AD) for all DG Aviation GmbH (Type Certificate Previously Held by DG Flugzeugbau GmbH) Model DG-1000M gliders. This AD was prompted by reports of engine mount cracking near the propeller head. This AD requires updating the maintenance manual, inspecting the engine mount for cracks, and taking corrective actions if cracks are found. This AD also requires performing a powerplant belt tension inspection and, depending on the results of the inspection, adjusting the belt tension. This AD also requires balancing the propeller assembly and installing a carbon fiber reinforced plastic (CFRP) bracket. This AD also prohibits accomplishing certain maintenance actions in the maintenance manual. The FAA is issuing this AD to address the unsafe condition on these products.
Full Text
<html>
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<title>Federal Register, Volume 91 Issue 64 (Friday, April 3, 2026)</title>
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<body><pre>
[Federal Register Volume 91, Number 64 (Friday, April 3, 2026)]
[Rules and Regulations]
[Pages 16815-16818]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-06534]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2026-2727; Project Identifier MCAI-2025-00685-G;
Amendment 39-23298; AD 2026-07-03]
RIN 2120-AA64
Airworthiness Directives; DG Aviation GmbH (Type Certificate
Previously Held by DG Flugzeugbau GmbH) 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
DG Aviation GmbH (Type Certificate Previously Held by DG Flugzeugbau
GmbH) Model DG-1000M gliders. This AD was prompted by reports of engine
mount cracking near the propeller head. This AD requires updating the
maintenance manual, inspecting the engine mount for cracks, and taking
corrective actions if cracks are found. This AD also requires
performing a powerplant belt tension inspection and, depending on the
results of the inspection, adjusting the belt tension. This AD also
requires balancing the propeller assembly and installing a carbon fiber
reinforced plastic (CFRP) bracket. This AD also prohibits accomplishing
certain maintenance actions in the maintenance manual. The FAA is
issuing this AD to address the unsafe condition on these products.
DATES: This AD is effective April 20, 2026.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of April 20,
2026.
The FAA must receive comments on this AD by May 18, 2026.
ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:
<bullet> Federal eRulemaking Portal: Go to <a href="http://regulations.gov">regulations.gov</a>. Follow
the instructions for submitting comments.
<bullet> Fax: (202) 493-2251.
<bullet> 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.
<bullet> 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 <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2026-2727; 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:
<bullet> For DG Aviation GmbH material identified in this AD,
contact DG Aviation GmbH, Rita Rodrigues, Otto Lilienthal Weg 2/Am
Flugplatz, Bruchsal, Germany; phone: +49 (0) 7251 36660-32; email:
<a href="/cdn-cgi/l/email-protection#90e2fff4e2f9f7e5f5e3d0f4f7bdf1e6f9f1e4f9fffebef4f5"><span class="__cf_email__" data-cfemail="a1d3cec5d3c8c6d4c4d2e1c5c68cc0d7c8c0d5c8cecf8fc5c4">[email protected]</span></a>; website: dg-aviation.de/en/dg-flugzeugbau/
contact.
<bullet> 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 <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2026-2727.
FOR FURTHER INFORMATION CONTACT: For more information about this AD,
contact Evan Weaver, Aviation Safety Engineer, FAA, 1600 Stewart
Avenue, Suite 410, Westbury, NY 11590; phone: (316) 944-8910; email:
<a href="/cdn-cgi/l/email-protection#07627166692977297062667162754761666629606871"><span class="__cf_email__" data-cfemail="ddb8abbcb3f3adf3aab8bcabb8af9dbbbcbcf3bab2ab">[email protected]</span></a>.
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-2026-2727; Project
Identifier MCAI-2025-00685-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
[[Page 16816]]
11.35, the FAA will post all comments received, without change, to
<a href="http://regulations.gov">regulations.gov</a>, 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 Evan
Weaver, 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 2025-0091, dated April 23, 2025 (EASA AD 2025-0091) (also
referred to as the MCAI), to correct an unsafe condition on DG Aviation
GmbH Model DG-1000M gliders. The MCAI states that occurrences of engine
mount cracking near the propeller head on DG-1000M powered gliders have
been reported. Given the urgency of the unsafe condition, EASA issued
the MCAI as a final rule with request for comments. To address this
potential unsafe condition, DG Aviation GmbH issued DG Aviation GmbH
Technical Note No. TN 1000/51, Doc. No. TM1000-51 FE-29-01, Issue 01.d,
dated February 26, 2025 (DG Aviation GmbH TN TM1000-51 FE-29-01, Issue
01.d), to provide inspection, repair, and modification instructions for
affected parts. This condition, if not addressed, could result in loss
of power transmission to the propeller and reduced or loss of control
of the glider.
You may examine the MCAI in the AD docket at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2026-2727.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed DG Aviation GmbH TN TM1000-51 FE-29-01, Issue
01.d. This material specifies procedures for updating the maintenance
manual, inspecting the engine mount for cracks, repairing the engine
mount, performing a powerplant belt tension inspection and adjustment,
installing a CFRP bracket, balancing the propeller assembly, and
updating the software in the front and rear cockpit DEI-NTs and the
control unit NT (E-box).
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 and material 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 Proposed AD and the Referenced Material.''
Differences Between This Proposed AD and the Referenced Material
Paragraph 1 of the Instructions section of DG Aviation GmbH TN
TM1000-51 FE-29-01, Issue 01.d, provides instructions to ``Exchange the
following Maintenance manual pages against new pages: 0.0, 0.2, 0.3,
0.5, 0.7, 0.13, 4.2, 4.19, 6.1, 6.2, diagram 21 issued January 2025,
marked with TN1000-51. Respect the marked changes.'' This AD, instead,
requires revising page 0.13 in accordance with paragraph 1 of the
Instructions section of DG Aviation GmbH TN TM1000-51 FE-29-01, Issue
01.d, dated February 26, 2025.
Paragraph 2 of the Instructions section of DG Aviation GmbH TN
TM1000-51 FE-29-01, Issue 01.d, provides instructions to contact DG
Aviation GmbH to obtain an approved repair and accomplish that repair
accordingly, including post-repair follow-on action(s), as applicable.
This AD instead requires contacting either the Manager, International
Validation Branch, FAA; EASA; or DG Aviation GmbH's EASA Design
Organization Approval (DOA); for approved repair instructions and,
within the compliance time specified therein, accomplish those
instructions accordingly, including post-repair follow-on action(s), as
applicable. If approved by the DOA, the approval must include the DOA-
authorized signature.
Although paragraph 6 of the Instructions section of DG Aviation
GmbH TN TM1000-51 FE-29-01, Issue 01.d, provides instructions to send
both front and rear cockpit DEI-NTs as well as the control unit-NT (E-
box) to DG Aviation for software updates, this AD does not require
those actions.
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 cracking of the engine mount near the propeller head could lead
to structural failure of the engine mount with consequent loss of power
transmission to the propeller, and reduced or loss of control of the
glider. Therefore, an inspection of the engine mount for cracks and a
power plant belt tension inspection are required before further flight,
or within 30 days of the effective date of this AD, whichever occurs
first. In addition, repair of the engine mount is required before
further flight if cracks are found during inspection. These compliance
times are 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
[[Page 16817]]
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 two gliders of U.S.
registry.
The FAA estimates the following costs to comply with this AD:
Estimated Costs
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Cost per Cost on U.S.
Action Labor cost Parts cost product operators
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Update maintenance manual................ 1 work-hour x $85 per hour $0 $85 $170
= $85.
Inspect engine mount..................... 1 work-hour x $85 per hour 0 85 170
= $85.
Accomplish powerplant belt tension 1 work-hour x $85 per hour 0 85 170
inspection. = $85.
Install CFRP bracket..................... 2 work-hours x $85 per hour 0 170 340
= $170.
Perform dynamic balancing of the 2 work-hours x $85 per hour 0 170 340
propeller assembly. = $170.
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The FAA estimates the following costs to do any repairs or
replacements 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 these repairs or replacements.
On-Condition Costs
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Cost per
Action Labor cost Parts cost product
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Repair engine mount............................ 4 work-hours x $85 per hour = $340 $0 $340
Adjust belt tension............................ 2 work-hours x $85 per hour = $170 0 170
Replace engine mount........................... 4 work-hours x $85 per hour = $340 0 340
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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 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:
2026-07-03 DG Aviation GmbH (Type Certificate Previously Held by DG
Flugzeugbau GmbH): Amendment 39-23298; Docket No. FAA-2026-2727;
Project Identifier MCAI-2025-00685-G.
(a) Effective Date
This airworthiness directive (AD) is effective April 20, 2026.
(b) Affected ADs
None.
(c) Applicability
This AD applies to all DG Aviation GmbH (type certificate
previously held by DG Flugzeugbau GmbH) Model DG-1000M gliders,
certificated in any category.
(d) Subject
Joint Aircraft System Component (JASC) Code 5346, Powerplant
Attach Fittings.
(e) Unsafe Condition
This AD was prompted by reports of the engine mount cracking
near the propeller head. The FAA is issuing this AD to detect and
correct indications of structural failure of the engine mount. The
unsafe condition, if not addressed, could result in loss of power
transmission to the propeller and reduced or loss of control of the
glider.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Definitions
For the purpose of this AD, the definitions in paragraphs (g)(1)
through (3) of this AD apply.
(1) An ``affected part'' is a steel frame engine mount having
part number (P/N) 10M112.
[[Page 16818]]
(2) A ``serviceable part'' is an affected part which is new
(never previously installed on any glider), or a part that has
passed the engine mount inspection prior to installation in
accordance with Instructions 2 of DG Aviation GmbH Technical Note
No. TN 1000/51, Doc. No. TM1000-51 FE-29-01, Issue 01.d, dated
February 26, 2025 (DG Aviation GmbH TN TM1000-51 FE-29-01, Issue
01.d).
(3) The ``Old MM'' task is the DG Aviation Maintenance Manual
(MM) for DG-1000M, task 4.10.2 ``Mounting and tensioning of the
drive belts'', issued before January 2025.
(h) Required Actions
(1) Before the next engine operation after the effective date of
this AD, revise page 0.13 of the applicable MM in accordance with
paragraph 1 of the Instructions section of DG Aviation GmbH TN
TM1000-51 FE-29-01, Issue 01.d.
(2) Before the next engine operation after the effective date of
this AD, inspect the affected part for cracks and, if necessary,
before further flight, do one of the following:
(i) Repair or replace the affected part, as applicable, in
accordance with paragraph 2 of the Instructions section of DG
Aviation GmbH TN TM1000-51 FE-29-01, Issue 01.d; or
(ii) Contact either the Manager, International Validation
Branch, FAA; European Union Aviation Safety Agency (EASA); or DG
Aviation GmbH's EASA Design Organization Approval (DOA); for
approved repair instructions and, within the compliance time
specified therein, accomplish those instructions accordingly,
including post-repair follow-on action(s), as applicable. If
approved by the DOA, the approval must include the DOA-authorized
signature; or
(iii) Replace an affected part with a serviceable part.
(3) Before the next engine operation after the effective date of
this AD, accomplish the powerplant belt tension inspection and, if
necessary, adjust the belt tension in accordance with paragraph 3 of
the Instructions section of DG Aviation GmbH TN TM1000-51 FE-29-01,
Issue 01.d.
(4) Within 15 hours time-in-service (TIS) of engine operation or
11 months, whichever occurs first after the effective date of this
AD, install a carbon fiber-reinforced plastic (CFRP) bracket having
P/N 10M227 between the brackets of the two upper drive belt guide
rollers in accordance with paragraph 4 of the Instructions section
of DG Aviation GmbH TN TM1000-51 FE-29-01, Issue 01.d.
(5) Within 15 hours TIS of engine operation or 11 months,
whichever occurs first after the effective date of this AD, perform
dynamic balancing of the propeller assembly in accordance with
paragraph 5 of the Instructions section of DG Aviation GmbH TN
TM1000-51 FE-29-01, Issue 01.d.
(6) From the effective date of this AD, do not accomplish any
maintenance action on a sailplane in accordance with the
instructions of the old MM task, as defined in paragraph (g)(3) of
this AD.
(i) Installation Prohibition
As of the effective date of this AD, do not install a steel
frame engine mount that is an affected part as defined in paragraph
(g)(1) of this AD on any glider, unless it is a serviceable part as
defined in paragraph (g)(2) of this AD.
(j) Special Flight Permits
A one-time special flight permit may be issued in accordance
with 14 CFR 21.197 and 21.199 only in order to fly to a maintenance
base to perform the required action in this AD and must specify that
the engine not be operated.
(k) 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 (l) of
this AD and email to <a href="/cdn-cgi/l/email-protection#fbbab6b4b8bb9d9a9ad59c948d"><span class="__cf_email__" data-cfemail="dd9c90929e9dbbbcbcf3bab2ab">[email protected]</span></a>. 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.
(l) Additional Information
For more information about this AD, contact Evan Weaver,
Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410,
Westbury, NY 11590; phone: (316) 944-8910; email:
<a href="/cdn-cgi/l/email-protection#a7c2d1c6c989d789d0c2c6d1c2d5e7c1c6c689c0c8d1"><span class="__cf_email__" data-cfemail="2b4e5d4a45055b055c4e4a5d4e596b4d4a4a054c445d">[email protected]</span></a>.
(m) 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) DG Aviation GmbH Technical Note No. TN 1000/51, Doc. No.
TM1000-51 FE-29-01, Issue 01.d, dated February 26, 2025.
(ii) [Reserved]
(3) For DG Aviation GmbH material identified in this AD, contact
DG Aviation GmbH, Rita Rodrigues, Otto Lilienthal Weg 2/Am
Flugplatz, Bruchsal, Germany; phone: +49 (0) 7251 36660-32; email:
<a href="/cdn-cgi/l/email-protection#8cfee3e8fee5ebf9e9ffcce8eba1edfae5edf8e5e3e2a2e8e9"><span class="__cf_email__" data-cfemail="35475a51475c524050467551521854435c54415c5a5b1b5150">[email protected]</span></a>; website: dg-aviation.de/en/dg-flugzeugbau/
contact.
(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 <a href="http://www.archives.gov/federal-register/cfr/ibr-locations">www.archives.gov/federal-register/cfr/ibr-locations</a> or email <a href="/cdn-cgi/l/email-protection#6a0c18440304191a0f091e0305042a040b180b440d051c"><span class="__cf_email__" data-cfemail="b4d2c69adddac7c4d1d7c0dddbdaf4dad5c6d59ad3dbc2">[email protected]</span></a>.
Issued on March 24, 2026.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2026-06534 Filed 4-2-26; 8:45 am]
BILLING CODE 4910-13-P
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