Proposed Rule2025-23794
Airworthiness Directives; Diamond Aircraft Industries Inc. Airplanes
Primary source
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Published
December 23, 2025
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA proposes to supersede Airworthiness Directive (AD) 2020-14-06, which applies to all Diamond Aircraft Industries Inc. (DAI) Model DA 40, DA 40 F, and DA 40 NG airplanes. AD 2020-14-06 requires replacing affected parts, inspecting the fuel tank chambers, and removing rubber material that has detached from the fuel tank connection hoses. AD 2020-14-06 also prohibits installing an affected part on any airplane. Since the FAA issued AD 2020-14-06, additional affected parts installed during production on Model DA 40 NG airplanes have been reported. As a result, the manufacturer has published updated service material for the Model DA 40 NG. This proposed AD would require the same actions as AD 2020-14-06 and would require updated service material to be used for the Model DA 40 NG airplanes. The FAA is proposing this AD to address the unsafe condition on these products.
Full Text
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<title>Federal Register, Volume 90 Issue 244 (Tuesday, December 23, 2025)</title>
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[Federal Register Volume 90, Number 244 (Tuesday, December 23, 2025)]
[Proposed Rules]
[Pages 60031-60034]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-23794]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2025-5397; Project Identifier MCAI-2025-00972-A]
RIN 2120-AA64
Airworthiness Directives; Diamond Aircraft Industries Inc.
Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: The FAA proposes to supersede Airworthiness Directive (AD)
2020-14-06, which applies to all Diamond Aircraft Industries Inc. (DAI)
Model DA 40, DA 40 F, and DA 40 NG airplanes. AD 2020-14-06 requires
replacing affected parts, inspecting the fuel tank chambers, and
removing rubber material that has detached from the fuel tank
connection hoses. AD 2020-14-06 also prohibits installing an affected
part on any airplane. Since the FAA issued AD 2020-14-06, additional
affected parts installed during production on Model DA 40 NG
[[Page 60032]]
airplanes have been reported. As a result, the manufacturer has
published updated service material for the Model DA 40 NG.
This proposed AD would require the same actions as AD 2020-14-06
and would require updated service material to be used for the Model DA
40 NG airplanes. The FAA is proposing this AD to address the unsafe
condition on these products.
DATES: The FAA must receive comments on this NPRM by February 6, 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-2025-5397; 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 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 Diamond Aircraft Industries material identified in
this proposed AD, contact DAI, 1560 Crumlin Sideroad, London, Ontario,
Canada, N5V 1S2; phone: (519) 457-4041, fax: (519) 457-4045; email:
<a href="/cdn-cgi/l/email-protection#16656366667964623b75777877727756727f777b797872777f6475647770623875797b"><span class="__cf_email__" data-cfemail="33404643435c41471e50525d52575273575a525e5c5d57525a4150415255471d505c5e">[email protected]</span></a>.
<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.
FOR FURTHER INFORMATION CONTACT: Joseph Catanzaro, Aviation Safety
Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
phone: (516) 228-7366; email: <a href="/cdn-cgi/l/email-protection#2b4144584e5b4305484a5f4a45514a59446b4d4a4a054c445d"><span class="__cf_email__" data-cfemail="c3a9acb0a6b3abeda0a2b7a2adb9a2b1ac83a5a2a2eda4acb5">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION:
Comments Invited
The FAA invites you to send any written relevant data, views, or
arguments about this proposal. Send your comments using a method listed
under ADDRESSES. Include ``Docket No. FAA-2025-5397; Project Identifier
MCAI-2025-00972-A'' 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
the proposal 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
<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 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
Joseph Catanzaro, 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 FAA issued AD 2020-14-06, Amendment 39-21160 (85 FR 42687, July
15, 2020) (AD 2020-14-06), for DAI Model DA 40, DA 40 F, and DA 40 NG
airplanes (including Model DA 40 NG airplanes that have been converted
from the Model DA 40 D), all serial numbers, certificated in any
category. AD 2020-14-06 was prompted by AD CF-2019-39, dated October
31, 2019 (Transport Canada AD CF-2019-39) issued by Transport Canada,
which is the aviation authority for Canada. Transport Canada issued
Transport Canada AD CF-2019-39 to correct an unsafe condition
identified as fuel tank connection hose deterioration.
AD 2020-14-06 requires replacing affected parts, inspecting the
fuel tank chambers, and removing rubber material that has detached from
the fuel tank connection hoses. AD 2020-14-06 also prohibits installing
an affected part on any airplane. The FAA issued AD 2020-14-06 to
detect deterioration of fuel tank connection hoses, which, if not
corrected, could result in contamination of the fuel system and
restriction of fuel flow, and could lead to fuel starvation and reduced
control of the airplane.
Actions Since AD 2020-14-06 Was Issued
Since the FAA issued AD 2020-14-06, Transport Canada superseded
Transport Canada AD CF-2019-39 and issued Transport Canada AD CF-2019-
39R1, dated May 21, 2025 (also referred to as the MCAI). The MCAI
states that since the issuance of Transport Canada AD CF-2019-39,
Transport Canada has received reports of affected parts installed
during production on DAI Model DA 40 NG airplanes. As a result, the
manufacturer published updated service material for the Model DA 40 NG.
The MCAI also continues to require replacing affected fuel tank
connection hoses, inspecting the fuel tank chambers, and removing
rubber material that has detached from the fuel tank connection hoses.
You may examine the MCAI in the AD docket at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2025-5397.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed Diamond Aircraft Industries Mandatory Service
Bulletin No. MSB 40NG-064 Rev. 3, dated January 23, 2025, which
specifies procedures for replacing affected parts, inspecting the fuel
tank chambers, and removing rubber material that has detached from the
hoses. This material also specifies the service centers from which the
affected parts could have been obtained, and the serial numbers for
additional DAI Model DA 40 NG airplanes that are affected by the unsafe
condition and were not in the previous version of the material.
This proposed AD would also require the following Diamond Aircraft
Industries Mandatory Service Bulletins, which the Director of the
Federal Register approved for incorporation by reference as of August
4, 2020 (85 FR 42687, July 15, 2020):
<bullet> Diamond Aircraft Industries Mandatory Service Bulletin No.
MSB 40-087, Revision 3, dated November 5, 2019.
[[Page 60033]]
<bullet> Diamond Aircraft Industries Mandatory Service Bulletin No.
MSB F4-037, Revision 3, dated November 5, 2019.
<bullet> Diamond Aircraft Industries Work Instruction WI-MSB 40-
087, Revision 0, dated July 1, 2019.
<bullet> Diamond Aircraft Industries Work Instruction WI-MSB F4-
037, Revision 0, dated July 1, 2019.
<bullet> Diamond Aircraft Industries Work Instruction WI-MSB 40 NG-
064, Revision 0, dated July 1, 2019.
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 NPRM after determining that the unsafe condition described
previously is likely to exist or develop on other products of the same
type design.
Proposed AD Requirements in This NPRM
This proposed AD would require the same actions as AD 2020-14-06
and would require updated material to be used for the Model DA 40 NG
airplanes.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 987 airplanes of U.S. registry.
The FAA estimates the following costs to comply with this proposed
AD:
Estimated Costs
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Cost per Cost on U.S.
Action Labor cost Parts cost product operators
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Inspect the fuel tank chambers......... 1 work-hour x $85 per hour $0 $85 $83,895
= $85.
Remove detached rubber material........ 5 work hours x $85 per 0 425 419,475
hour = $425.
Replace fuel tank connection hose...... 10 work hours x $85 per 383 1,233 1,216,971
hour = $850.
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The FAA has included all known costs in its cost estimate.
According to the manufacturer, however, some of the costs of this
proposed AD may be covered under warranty, thereby reducing the cost
impact on affected operators.
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
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 that the 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:
0
a. Removing Airworthiness Directive AD 2020-14-06, Amendment 39-21160
(85 FR 42687, July 15, 2020); and
0
b. Adding the following new airworthiness directive:
Diamond Aircraft Industries Inc.: Docket No. FAA-2025-5397; Project
Identifier MCAI-2025-00972-A.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive
(AD) by February 6, 2026.
(b) Affected ADs
This AD replaces AD 2020-14-06, Amendment 39-21160 (85 FR 42687,
July 15, 2020); (AD 2020-14-06).
(c) Applicability
This AD applies to all Diamond Aircraft Industries Inc. Model DA
40, DA 40 F, and DA 40 NG airplanes (including Model DA 40 NG
airplanes that have been converted from the Model DA 40 D),
certificated in any category.
(d) Subject
Joint Aircraft System Component (JASC) Code 1410, Hoses and
tubes.
(e) Unsafe Condition
This AD was prompted by reports of fuel tank connection hose
deterioration and reports of affected parts that were installed
during production on Model DA 40 NG airplanes. The FAA is issuing
this AD to detect and address such deterioration, which, if not
corrected, could result in contamination of the fuel system and
restriction of fuel flow, and could lead to fuel starvation and
reduced control of the airplane.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Definitions
(1) For the purpose of this AD, ``affected part'' means a fuel
tank connection hose that meets the criteria in paragraph (g)(1)(i),
(ii), or (iii) of this AD.
(i) Part number (P/N) D4D-2817-10-70 installed during production
on Model DA 40
[[Page 60034]]
NG airplanes with a serial number listed in Section I.2. of Diamond
Aircraft Industries Mandatory Service Bulletin MSB 40NG-064 Rev. 3,
dated January 23, 2025; or
(ii) P/N D4D-2817-10-70 or BENOLPRESS (no part number) purchased
between July 13, 2017, and February 26, 2019, as listed in Section
I.11 of Diamond Aircraft Industries Mandatory Service Bulletin No.
MSB 40-087, Revision 3, dated November 5, 2019; Diamond Aircraft
Industries Mandatory Service Bulletin No. MSB 40NG-064 Rev. 3, dated
January 23, 2025; or Diamond Aircraft Industries Mandatory Service
Bulletin No. MSB F4-037, Revision 3, dated November 5, 2019; or
(iii) P/N D4D-2817-10-70 installed as a replacement part on or
after July 13, 2017, if it is unknown whether the part meets the
criteria in paragraph (g)(1)(i) or (ii) of this AD.
(h) Required Actions
Within 100 hours time-in-service or within 2 months, whichever
occurs first after the effective date of this AD, replace each
affected part as defined in paragraph (g) of this AD, inspect the
main fuel tank chambers, and remove any detached rubber material in
accordance with Sections III.1 and III.2 of the Instructions in
Diamond Aircraft Industries Work Instruction WI-MSB 40-087, Revision
0, dated July 1, 2019; Diamond Aircraft Industries Work Instruction
WI-MSB F4-037, Revision 0, dated July 1, 2019; or Diamond Aircraft
Industries Work Instruction WI-MSB 40NG-064, Revision 0, dated July
1, 2019; as applicable to your model airplane.
(i) No Reporting Requirement
Although the service material specifies to submit information to
the manufacturer, this AD does not require that action.
(j) Installation Prohibition
As of the effective date of this AD, do not install an affected
part, as defined in paragraph (g) of this AD, on any airplane.
(k) Credit for Previous Actions
This paragraph provides credit for the actions required by
paragraph (h) of this AD if those actions were performed before the
effective date of this AD, and the affected part for the Model DA 40
NG airplane was identified using Diamond Aircraft Industries
Mandatory Service Bulletin No. MSB 40NG-064, Revision 2, dated
August 29, 2019.
(l) 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 International Validation Branch, send
it to the attention of the person identified in paragraph (m)(1) of
this AD and email it to: <a href="/cdn-cgi/l/email-protection#51101c1e12113730307f363e27"><span class="__cf_email__" data-cfemail="1554585a56557374743b727a63">[email protected]</span></a>.
(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.
(m) Additional Information
(1) For more information about this AD, contact Joseph
Catanzaro, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite
410, Westbury, NY 11590; phone: (516) 228-7366; email:
<a href="/cdn-cgi/l/email-protection#f09a9f83958098de939184919e8a91829fb0969191de979f86"><span class="__cf_email__" data-cfemail="fe94918d9b8e96d09d9f8a9f90849f8c91be989f9fd0999188">[email protected]</span></a>.
(2) Material identified in this AD that is not incorporated by
reference is available at the address specified in paragraph (n)(5)
of this AD.
(n) 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.
(3) The following material was approved for IBR on February 6,
2026.
(i) Diamond Aircraft Industries Mandatory Service Bulletin MSB
40NG-064 Rev. 3, dated January 23, 2025.
(ii) [Reserved]
(4) The following material was approved for IBR on August 4,
2020 (85 FR 42687, July 15, 2020).
(i) Diamond Aircraft Industries Mandatory Service Bulletin No.
MSB 40-087, Revision 3, dated November 5, 2019.
(ii) Diamond Aircraft Industries Mandatory Service Bulletin No.
MSB F4-037, Revision 3, dated November 5, 2019.
(iii) Diamond Aircraft Industries Work Instruction WI-MSB 40-
087, Revision 0, dated July 1, 2019.
(iv) Diamond Aircraft Industries Work Instruction WI-MSB 40NG-
064, Revision 0, dated July 1, 2019.
(v) Diamond Aircraft Industries Work Instruction WI-MSB F4-037,
Revision 0, dated July 1, 2019.
(5) For Diamond Aircraft Industries material identified in this
AD, contact Diamond Aircraft Industries Inc., 1560 Crumlin Sideroad,
London, Ontario, Canada, N5V 1S2; phone: (519) 457-4041, fax: (519)
457-4045; email: <a href="/cdn-cgi/l/email-protection#8af9fffafae5f8fea7e9ebe4ebeeebcaeee3ebe7e5e4eeebe3f8e9f8ebecfea4e9e5e7"><span class="__cf_email__" data-cfemail="1f6c6a6f6f706d6b327c7e717e7b7e5f7b767e7270717b7e766d7c6d7e796b317c7072">[email protected]</span></a>.
(6) 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.
(7) 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#462034682f2835362325322f2928062827342768212930"><span class="__cf_email__" data-cfemail="3b5d49155255484b5e584f5254557b555a495a155c544d">[email protected]</span></a>.
Issued on December 16, 2025.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2025-23794 Filed 12-22-25; 8:45 am]
BILLING CODE 4910-13-P
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