[Federal Register Volume 90, Number 148 (Tuesday, August 5, 2025)]
[Proposed Rules]
[Pages 37434-37437]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-14830]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2025-1728; Project Identifier MCAI-2025-00076-T]
RIN 2120-AA64
Airworthiness Directives; Bombardier, Inc., Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
-----------------------------------------------------------------------
SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD)
for all Bombardier, Inc., Model CL-600-2A12 (601) and CL-600-2B16 (601-
3A, 601-3R, and 604 Variants) airplanes. This proposed AD was prompted
by a determination that new or more restrictive airworthiness
limitations are necessary. This proposed AD would require revising the
existing maintenance or inspection program, as applicable, to
incorporate new or more restrictive airworthiness limitations. 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 September
19, 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-
[[Page 37435]]
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-2025-1728; 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:
For Bombardier material identified in this proposed AD,
contact Bombardier Business Aircraft Customer Response Center, 400
C[ocirc]te-Vertu Road West, Dorval, Qu[eacute]bec H4S 1Y9, Canada;
telephone 514-855-2999; email bombardier.com">ac.yul@aero.bombardier.com; website
bombardier.com.
You may view this material at the FAA, Airworthiness
Products Section, Operational Safety Branch, 2200 South 216th St., Des
Moines, WA. For information on the availability of this material at the
FAA, call 206-231-3195.
FOR FURTHER INFORMATION CONTACT: Joseph Catanzaro, Aviation Safety
Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
telephone 516-228-7300; email [email protected].
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-2025-1728;
Project Identifier MCAI-2025-00076-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 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
regulations.gov, 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; telephone 516-228-7300; email [email protected]. Any commentary that the FAA receives that is not
specifically designated as CBI will be placed in the public docket for
this rulemaking.
Background
Transport Canada, which is the aviation authority for Canada, has
issued Transport Canada AD CF-2025-06, dated January 20, 2025
(Transport Canada AD CF-2025-06) (also referred to as the MCAI), to
correct an unsafe condition for all Bombardier, Inc., Model CL-600-2A12
(601), and CL-600-2B16 (601-3A, 601-3R, and 604 Variants) airplanes.
The MCAI states that new or more restrictive airworthiness limitations
have been developed. The flightcrew of a Challenger airplane started
the auxiliary power unit (APU) during the approach and allowed it to
run for approximately 10 minutes after landing. When the flightcrew
shut the APU down, an APU FIRE warning message was posted on the engine
indicating and crew alerting system (EICAS). The APU fire suppression
was discharged; however, the fire was not fully extinguished following
the discharge of the fire bottles. Upon further investigation, it was
discovered that a fuel solenoid valve was leaking, and the APU muffler
drainage was blocked leading to an accumulation of fuel in the muffler.
The fuel in the APU muffler was ignited by the high-temperature exhaust
gases in the muffler.
The FAA is proposing this AD to address an accumulation of fuel in
the muffler caused by a drainage block in the APU muffler. This
condition, if not corrected, could lead to an accumulation of fuel in
the muffler being ignited by the high-temperature exhaust gases in the
muffler, and could subsequently lead to an uncontrolled fire in the APU
bay. You may examine the MCAI in the AD docket at regulations.gov under
Docket No. FAA-2025-1728.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed the following Bombardier material:
Temporary Revision No. 5-2-6, dated June 28, 2024, which
includes new Task 49-15-01-101*, ``Functional Test of the Auxiliary
Power Unit (APU) Muffler Drain.''
Temporary Revision No. 5-2-30, dated June 28, 2024, which
includes new Task 49-15-01-101*, ``Functional Test of the Auxiliary
Power Unit (APU) Muffler Drain.''
Temporary Revision No. 5-2-74, dated June 28, 2024, which
includes new Task 49-15-01-101*, ``Functional Test of the Auxiliary
Power Unit (APU) Muffler Drain (A/C 5301 to 5630, Post SB 604-49-006,
and A/C 5631 and Subs).''
Temporary Revision No. TR 5-271, dated September 30, 2024,
which includes, among other tasks, new Task 49-15-01-101*, ``Functional
Test of the APU Muffler Drain.''
Temporary Revision No. TR 5-285, dated September 30, 2024,
which includes, among other tasks, new Task 49-15-01-101*, ``Functional
Test of the APU Muffler Drain.''
(The asterisk (or ``one star'') with the last three digits of the
task numbers listed above indicates that the task is an airworthiness
limitation task.)
Temporary Revision No. 5-2-6, 5-2-30, 5-2-74, TR 5-271, and TR 5-
285 introduce, among other tasks, functional tests of the APU muffler
drain. These documents are distinct since they apply to different
airplane configurations.
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
proposing this AD because the FAA evaluated all the relevant
information
[[Page 37436]]
and determined the unsafe condition described previously is likely to
exist or develop on other products of the same type design.
Proposed Requirements of This NPRM
This proposed AD would require revising the existing maintenance or
inspection program, as applicable, to incorporate new or more
restrictive airworthiness limitations.
This proposed AD would require revisions to certain operator
maintenance documents to include new actions (e.g., inspections).
Compliance with these actions is required by 14 CFR 91.403(c). For
airplanes that have been previously modified, altered, or repaired in
the areas addressed by this proposed AD, the operator may not be able
to accomplish the actions described in the revisions. In this
situation, to comply with 14 CFR 91.403(c), the operator must request
approval for an alternative method of compliance according to paragraph
(i)(1) of this proposed AD.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 550 airplanes of U.S. registry. The FAA estimates the following
costs to comply with this proposed AD:
The FAA has determined that revising the maintenance or inspection
program takes an average of 90 work-hours per operator, although the
agency recognizes that this number may vary from operator to operator.
Since operators incorporate maintenance or inspection program changes
for their affected fleet(s), the FAA has determined that a per-operator
estimate is more accurate than a per-airplane estimate. Therefore, the
agency estimates the average total cost per operator to be $7,650 (90
work-hours x $85 per work-hour).
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 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 adding the following new airworthiness
directive:
Bombardier, Inc.: Docket No. FAA-2025-1728; Project Identifier MCAI-
2025-00076-T.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive
(AD) by September 19, 2025.
(b) Affected ADs
None.
(c) Applicability
This AD applies to all Bombardier, Inc., Model CL-600-2A12 (601)
and CL-600-2B16 (601-3A, 601-3R, and 604 Variants) airplanes,
certificated in any category.
(d) Subject
Air Transport Association (ATA) of America Code 49, Auxiliary
Power.
(e) Unsafe Condition
This AD was prompted by a determination that new or more
restrictive airworthiness limitations are necessary. The FAA is
issuing this AD to address an accumulation of fuel in the muffler
caused by a drainage block in the Auxiliary Power Unit (APU)
muffler. This condition if not corrected, could lead to an
accumulation of fuel in the muffler being ignited by the high-
temperature exhaust gases in the muffler, and could subsequently
lead to an uncontrolled fire in the APU bay.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Maintenance or Inspection Program Revision
Within 90 days after the effective date of this AD, revise the
existing maintenance or inspection program, as applicable, to
incorporate the information specified in the applicable tasks
identified in figure 1 to paragraph (g) of this AD. The initial
compliance time for doing the tasks is at the time specified in the
applicable tasks identified in figure 1 to paragraph (g) of this AD,
or within 90 days after the effective date of this AD, whichever
occurs later.
Figure 1 to Paragraph (g)--Temporary Revisions and Tasks
------------------------------------------------------------------------
Task Nos. and
For model Temporary revision title
------------------------------------------------------------------------
Bombardier, Inc., Model CL-600- Bombardier Task 49-15-01-
2A12 (601) airplanes. Temporary 101*,
Revision No. TR 5- ``Functional Test
271, dated of the APU
September 30, Muffler Drain''.
2024.
Bombardier, Inc., CL-600-2B16 Bombardier Task 49-15-01-
(601-3A and 601-3R Variants) Temporary 101*,
airplanes. Revision No. TR 5- ``Functional Test
285, dated of the APU
September 30, Muffler Drain''.
2024.
Bombardier, Inc., CL-600-2B16 Bombardier Task 49-15-01-
(604 Variant) airplanes Temporary 101*,
(Challenger 604). Revision No. 5-2- ``Functional Test
74, dated June of the Auxiliary
28, 2024. Power Unit (APU)
Muffler Drain (A/
C 5301 to 5630,
Post SB 604-49-
006, and A/C 5631
and Subs).''
[[Page 37437]]
Bombardier, Inc., CL-600-2B16 Bombardier Task 49-15-01-
(604 Variant) airplanes Temporary 101*,
(Challenger 605). Revision No. 5-2- ``Functional Test
30, dated June of the Auxiliary
28, 2024. Power Unit (APU)
Muffler Drain.''
Bombardier, Inc., CL-600-2B16 Bombardier Task 49-15-01-
(604 Variant) airplanes Temporary 101*,
(Challenger 650). Revision No. TR 5- ``Functional Test
2-6, dated June of the Auxiliary
28, 2024. Power Unit (APU)
Muffler Drain.''
------------------------------------------------------------------------
Note 1 to figure 1 to paragraph (g): The asterisk (or ``one
star'') with the last three digits of the task numbers listed in
table 1 to paragraph (g) of this AD indicates that the task is an
airworthiness limitation task.
(h) No Alternative Actions, Intervals
After the existing maintenance or inspection program has been
revised as required by paragraph (g) of this AD, no alternative
actions (e.g., inspections) or intervals may be used unless the
actions and intervals are approved as an alternative method of
compliance (AMOC) in accordance with the procedures specified in
paragraph (i)(1) of this AD.
(i) Additional AD Provisions
The following provisions also apply to this AD:
(1) 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 responsible Flight Standards 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 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, International
Validation Branch, FAA; or Transport Canada; or Bombardier'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 Joseph Catanzaro,
Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410,
Westbury, NY 11590; telephone 516-228-7300; email [email protected].
(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) Bombardier Temporary Revision No. 5-2-6, dated June 28,
2024.
(ii) Bombardier Temporary Revision No. 5-2-30, dated June 28,
2024.
(iii) Bombardier Temporary Revision No. 5-2-74, dated June 28,
2024.
(iv) Bombardier Temporary Revision No. TR 5-271, dated September
30, 2024.
(v) Bombardier Temporary Revision No. TR 5-285, dated September
30, 2024.
(3) For Bombardier material identified in this AD, contact
Bombardier Business Aircraft Customer Response Center, 400
C[ocirc]te-Vertu Road West, Dorval, Qu[eacute]bec H4S 1Y9, Canada;
telephone 514-855-2999; email bombardier.com">ac.yul@aero.bombardier.com; website
bombardier.com.
(4) You may view this material at the FAA, Airworthiness
Products Section, Operational Safety Branch, 2200 South 216th St.,
Des Moines, WA. 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 www.archives.gov/federal-register/cfr/[email protected]">www.archives.gov/federal-register/cfr/[email protected].
Issued on August 1, 2025.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2025-14830 Filed 8-4-25; 8:45 am]
BILLING CODE 4910-13-P