Airworthiness Directives; Airbus Canada Limited Partnership (Type Certificate Previously Held by C Series Aircraft Limited Partnership (CSALP); Bombardier, Inc.) Airplanes

Issuing agencies

Abstract

The FAA proposes to supersede Airworthiness Directive (AD) 2021-13-20, which applies to certain Airbus Canada Limited Partnership Model BD-500-1A10 and BD-500-1A11 airplanes. AD 2021-13-20 requires inspecting the waste box, waste access doubler, and waste service door for corrosion, and doing applicable on-condition actions. Since the FAA issued AD 2021-13-20, the FAA has determined that a full secondary fuel vapor barrier must be applied. This proposed AD would retain all requirements of AD 2021-13-20 and would also require, for certain airplanes, an additional inspection of the waste box, waste access doubler, and waste service door for corrosion, and applicable on- condition actions. The FAA is proposing this AD to address the unsafe condition on these products.

Full Text

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<title>Federal Register, Volume 91 Issue 216 (Tuesday, November 10, 2026)</title>
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[Federal Register Volume 91, Number 216 (Tuesday, November 10, 2026)]
[Proposed Rules]
[Pages 72465-72467]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-22919]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2026-13807; Project Identifier MCAI-2026-00620-T]
RIN 2120-AA64


Airworthiness Directives; Airbus Canada Limited Partnership (Type 
Certificate Previously Held by C Series Aircraft Limited Partnership 
(CSALP); Bombardier, 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) 
2021-13-20, which applies to certain Airbus Canada Limited Partnership 
Model BD-500-1A10 and BD-500-1A11 airplanes. AD 2021-13-20 requires 
inspecting the waste box, waste access doubler, and waste service door 
for corrosion, and doing applicable on-condition actions. Since the FAA 
issued AD 2021-13-20, the FAA has determined that a full secondary fuel 
vapor barrier must be applied. This proposed AD would retain all 
requirements of AD 2021-13-20 and would also require, for certain 
airplanes, an additional inspection of the waste box, waste access 
doubler, and waste service door for corrosion, and applicable on-
condition actions. 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 December 
28, 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-2026-13807; 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 Transport Canada material identified in this proposed 
AD, contact Transport Canada, Transport Canada National Aircraft 
Certification, 159 Cleopatra Drive, Nepean, Ontario K1A 0N5, Canada; 
telephone 888-663-3639; email <a href="/cdn-cgi/l/email-protection#6135224f200813160e131509080f041212250813040215081704124c220e0f1208060f041205040f001708060003080d0815044f35222115024f06024f0200"><span class="__cf_email__" data-cfemail="5400177a153d26233b26203c3d3a312727103d263137203d22312779173b3a273d333a312730313a35223d3335363d383d20317a00171420377a33377a3735">[email&#160;protected]</span></a>. You may find this material on the 
Transport Canada website at tc.canada.ca/en/aviation. It is also 
available at <a href="http://regulations.gov">regulations.gov</a> under Docket No. FAA-2026-13807.
    <bullet> You may view this material at the FAA, Airworthiness 
Products Section, Operational Safety Branch, 2200 South 216th St., Des 
Moines, WA 98198. For information on the availability of this material 
at the FAA, call 206-231-3195.

FOR FURTHER INFORMATION CONTACT: Camille Seay, Aviation Safety 
Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 817-
222-5149; email: <a href="/cdn-cgi/l/email-protection#d192b0bcb8bdbdb4ff9dff82b4b0a891b7b0b0ffb6bea7"><span class="__cf_email__" data-cfemail="7d3e1c10141111185331532e181c043d1b1c1c531a120b">[email&#160;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 the ADDRESSES section. Include ``Docket No. FAA-2026-13807; 
Project Identifier MCAI-2026-00620-T'' 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 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 
Camille Seay, Aviation Safety Engineer, FAA, 2200 South 216th St., Des 
Moines, WA 98198; phone: 817-222-5149; email: <a href="/cdn-cgi/l/email-protection#81c2e0ece8edede4afcdafd2e4e0f8c1e7e0e0afe6eef7"><span class="__cf_email__" data-cfemail="c586a4a8aca9a9a0eb89eb96a0a4bc85a3a4a4eba2aab3">[email&#160;protected]</span></a>. 
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 2021-13-20, Amendment 39-21625 (86 FR 38223, July 
20, 2021) (AD 2021-13-20), for certain Airbus Canada Limited 
Partnership Model BD-500-1A10 and BD-500-1A11 airplanes. AD 2021-13-20 
was prompted by an MCAI originated by Transport Canada, which is the 
aviation authority for Canada. Transport Canada issued AD CF-2020-42, 
dated October 16, 2020 (Transport Canada AD CF-2020-42), to correct an 
unsafe condition.
    AD 2021-13-20 requires inspecting the waste box, waste access 
doubler, and waste service door for corrosion, and doing applicable on-
condition actions. The FAA issued AD 2021-13-20 to address this 
corrosion, which could lead to cracking or holes in the waste box or 
airplane skin, and consequent cabin pressure leakage and catastrophic 
structural damage of the airplane.

[[Page 72466]]

Actions Since AD 2021-13-20 Was Issued

    Since the FAA issued AD 2021-13-20, Transport Canada superseded 
Transport Canada AD CF-2020-42 and issued Transport Canada AD CF-2026-
26, dated June 19, 2026 (Transport Canada AD CF-2026-26) (also referred 
to as the MCAI), to correct an unsafe condition for certain Model BD-
500-1A10 and BD-500-1A11 airplanes.
    The MCAI states that corrosion, caused by leakage of wastewater 
from the waste service panel ball valve, has been reported on the waste 
box, waste access doubler, and waste service door at the rear fuselage, 
and that some corrosion findings have been severe enough to require 
structural repairs or replacement of the affected parts. Since 
Transport Canada AD CF-2020-42 was issued, the manufacturer revised the 
service information, designating the existing instructions as Part A 
and introducing a new Part B applicable to certain airplanes; Part A 
improves the prior instructions (i.e., Part A ensures a full 
application of secondary fuel vapor barrier to the entire waste box), 
and Part B adds repairs to the waste access doubler, replacement of 
fillet sealant, removal of corrosion-inhibiting compound, and 
application of secondary fuel vapor barrier (to the Part B inspection 
of the waste box, waste access doubler, and waste service door for 
corrosion, and applicable on-condition actions).
    The FAA is proposing this AD to address the unsafe condition on 
these products. You may examine the MCAI in the AD docket at 
<a href="http://regulations.gov">regulations.gov</a> under Docket No. FAA-2026-13807.

Explanation of Retained Requirements

    Although this proposed AD does not explicitly restate the 
requirements of AD 2021-13-20, this proposed AD would retain all of the 
requirements of AD 2021-13-20. Those requirements are referenced in 
Transport Canada AD CF-2026-26, which, in turn, is referenced in 
paragraph (g) of this proposed AD.

Material Incorporated by Reference Under 1 CFR Part 51

    Transport Canada AD CF-2026-26 specifies procedures for a general 
visual inspection of the waste box, waste access doubler, and waste 
service door for corrosion, applying secondary fuel barrier sealant 
(for certain airplanes), and applicable on-condition actions. On-
condition actions include repairing any corrosion found, applying 
secondary fuel barrier to the entire waste box, and applying corrosion 
protection.
    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 NPRM 
after determining that the unsafe condition described previously is 
likely to exist or develop in other products of the same type design.

Proposed AD Requirements in This NPRM

    This proposed AD would retain all of the requirements of AD 2021-
13-20. This proposed AD would require accomplishing the actions 
specified in Transport Canada AD CF-2026-26 described previously, 
except for any differences identified as exceptions in the regulatory 
text of this proposed AD.

Explanation of Required Compliance Information

    In the FAA's ongoing efforts to improve the efficiency of the AD 
process, the FAA developed a process to use some civil aviation 
authority (CAA) ADs as the primary source of information for compliance 
with requirements for corresponding FAA ADs. The FAA has been 
coordinating this process with manufacturers and CAAs. As a result, the 
FAA proposes to incorporate Transport Canada AD CF-2026-26 by reference 
in the FAA final rule. This proposed AD would, therefore, require 
compliance with Transport Canada AD CF-2026-26 in its entirety through 
that incorporation, except for any differences identified as exceptions 
in the regulatory text of this proposed AD. Material required by 
Transport Canada AD CF-2026-26 for compliance will be available at 
<a href="http://regulations.gov">regulations.gov</a> by searching for and locating Docket No. FAA-2026-13807 
after the FAA final rule is published.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 32 airplanes of U.S. registry. The FAA estimates the following 
costs to comply with this proposed AD:

                                      Estimated Costs for Required Actions
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Retained actions from AD 2021-13-20...  8 work-hours x $85 per                $0            $680         $21,760
                                         hour = $680.
New proposed actions..................  8 work-hours x $85 per               * 0             680          21,760
                                         hour = $680.
----------------------------------------------------------------------------------------------------------------
* The FAA has received no definitive data on which to base the cost estimates for the parts costs specified in
  this proposed AD.

    The FAA has received no definitive data on which to base the cost 
estimates for the on-condition actions specified in this proposed AD.

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

[[Page 72467]]

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:
0
a. Removing Airworthiness Directive (AD) 2021-13-20, Amendment 39-21625 
(86 FR 38223, July 20, 2021); and
0
b. Adding the following new AD:

Airbus Canada Limited Partnership (Type Certificate Previously Held 
by C Series Aircraft Limited Partnership (CSALP); Bombardier, Inc.): 
Docket No. FAA-2026-13807; Project Identifier MCAI-2026-00620-T.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by December 28, 2026.

(b) Affected ADs

    This AD replaces AD 2021-13-20, Amendment 39-21625 (86 FR 38223, 
July 20, 2021) (AD 2021-13-20).

(c) Applicability

    This AD applies to Airbus Canada Limited Partnership (Type 
Certificate previously held by C Series Aircraft Limited Partnership 
(CSALP); Bombardier, Inc.) Model BD-500-1A10 and BD-500-1A11 
airplanes, certificated in any category, as identified in Transport 
Canada AD CF-2026-26, dated June 19, 2026 (Transport Canada AD CF-
2026-26).

(d) Subject

    Air Transport Association (ATA) of America Code 53, Fuselage.

(e) Unsafe Condition

    This AD was prompted by reports of corrosion on the waste box, 
waste access doubler, and waste service door at the aft waste 
service port, caused by leakage of wastewater from the waste service 
panel ball valve. The FAA is issuing this AD to address this 
corrosion, which could lead to cracking or holes in the waste box or 
airplane skin, and consequent cabin pressure leakage and 
catastrophic structural damage of the airplane.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Requirements

    Except as specified in paragraph (h) of this AD: Comply with all 
required actions and compliance times specified in, and in 
accordance with, Transport Canada AD CF-2026-26.

(h) Exception to Transport Canada AD CF-2026-26

    (1) Where Transport Canada AD CF-2026-26 refers to its effective 
date, this AD requires using the effective date of this AD.
    (2) Where Transport Canada AD CF-2026-26 refers to hours air 
time, this AD requires using flight hours.
    (3) Where Part I of Transport Canada AD CF-2026-26 specifies a 
compliance time of ``Within 14,200 flight cycles or 56 months from 
the aeroplane date of manufacture, as identified on the 
identification plate of the aeroplane, whichever occurs first'' or 
``Within 9,900 flight cycles or 56 months from the aeroplane date of 
manufacture, as identified on the identification plate of the 
aeroplane, whichever occurs first'', depending on airplane 
configuration, to accomplish all applicable actions, this AD 
requires that corrosion repair be done before further flight after 
detection of corrosion, as identified in the applicable service 
information specified in Transport Canada AD CF-2026-26.
    (4) Where Part II of Transport Canada AD CF-2026-26 specifies 
``repair any corrosion found'', for this AD, replace that text with 
``repair any corrosion found before further flight''.

(i) Additional AD Provisions

    The following provisions also apply to this AD:
    (1) Alternative Methods of Compliance (AMOCs): The Manager, AIR-
520, Continued Operational Safety 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 responsible Flight Standards Office, 
as appropriate. If sending information directly to the manager of 
the Continued Operational Safety Branch, send it to the attention of 
the person identified in paragraph (j) of this AD and email to: 
<a href="/cdn-cgi/l/email-protection#adece0e2eeedcbcccc83cac2db"><span class="__cf_email__" data-cfemail="f3b2bebcb0b3959292dd949c85">[email&#160;protected]</span></a>. Before using any approved AMOC, notify your 
appropriate principal inspector, or lacking a principal inspector, 
the manager of the responsible Flight Standards Office.
    (2) Contacting the Manufacturer: For any requirement in this AD 
to obtain instructions from a manufacturer, the instructions must be 
accomplished using a method approved by the Manager, AIR-520, 
Continued Operational Safety Branch, FAA; or Transport Canada; or 
Airbus Canada Limited Partnership's Transport Canada Design Approval 
Organization (DAO). If approved by the DAO, the approval must 
include the DAO-authorized signature.

(j) Additional Information

    For more information about this AD, contact Camille Seay, 
Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 
98198; phone: 817-222-5149; email: <a href="/cdn-cgi/l/email-protection#cc8fada1a5a0a0a9e280e29fa9adb58caaadade2aba3ba"><span class="__cf_email__" data-cfemail="befddfd3d7d2d2db90f290eddbdfc7fed8dfdf90d9d1c8">[email&#160;protected]</span></a>.

(k) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference 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 this AD specifies otherwise.
    (i) Transport Canada AD CF-2026-26, dated June 19, 2026.
    (ii) [Reserved]
    (3) For Transport Canada material identified in this AD, contact 
Transport Canada, Transport Canada National Aircraft Certification, 
159 Cleopatra Drive, Nepean, Ontario K1A 0N5, Canada; telephone 888-
663-3639; email <a href="/cdn-cgi/l/email-protection#d98d9af798b0abaeb6abadb1b0b7bcaaaa9db0abbcbaadb0afbcaaf49ab6b7aab0beb7bcaabdbcb7b8afb0beb8bbb0b5b0adbcf78d9a99adbaf7bebaf7bab8"><span class="__cf_email__" data-cfemail="396d7a1778504b4e564b4d5150575c4a4a7d504b5c5a4d504f5c4a147a56574a505e575c4a5d5c57584f505e585b5055504d5c176d7a794d5a175e5a175a58">[email&#160;protected]</span></a>. You may find this material on 
the Transport Canada website at tc.canada.ca/en/aviation.
    (4) You may view this material at the FAA, Airworthiness 
Products Section, Operational Safety Branch, 2200 South 216th St., 
Des Moines, WA 98198. For information on the availability of this 
material at the FAA, call 206-231-3195.
    (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#264054084f4855564345524f4948664847544708414950"><span class="__cf_email__" data-cfemail="c9afbbe7a0a7bab9acaabda0a6a789a7a8bba8e7aea6bf">[email&#160;protected]</span></a>.

    Issued on November 6, 2026.
Lona C. Saccomando,
Acting Deputy Director, Integrated Certificate Management Division, 
Aircraft Certification Service.
[FR Doc. 2026-22919 Filed 11-9-26; 8:45 am]
BILLING CODE 4910-13-P


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