[4910-13-P]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2022-1154; Project Identifier MCAI-2022-00550-T]
RIN 2120-AA64
Airworthiness Directives; MHI RJ Aviation ULC (Type Certificate Previously Held
by 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
MHI RJ Aviation ULC Model CL-600-2C10 (Regional Jet Series 700, 701 & 702)
airplanes, Model CL-600-2C11 (Regional Jet Series 550) airplanes; Model CL-600-2D15
(Regional Jet Series 705) airplanes; Model CL-600-2D24 (Regional Jet Series 900)
airplanes; and Model CL-600-2E25 (Regional Jet Series 1000) airplanes. This proposed
AD was prompted by a report that the pressure switch gauge assembly for the cargo bay
fire extinguisher container has the potential to display an incorrect pressure under certain
environmental conditions. This proposed AD would require replacing affected high rate
of discharge (HRD) and low rate of discharge (LRD) pressure switch gauge assemblies
for the cargo bay fire extinguisher container. 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 [INSERT DATE 45
DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL REGISTER].
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.
For service information identified in this NPRM, contact MHI RJ Aviation
Group, Customer Response Center, 3655 Ave. des Grandes-Tourelles, Suite 110,
Boisbriand, Québec J7H 0E2 Canada; North America toll-free telephone 833-990-7272
or direct-dial telephone 450-990-7272; fax 514-855-8501; email thd.crj@mhirj.com;
Internet mhirj.com. You may view this service information 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.
Examining the AD Docket
You may examine the AD docket at regulations.gov by searching for and locating
Docket No. FAA-2022-1154; 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, any comments received, and other information. The street address for Docket
Operations is listed above.
FOR FURTHER INFORMATION CONTACT: Gabriel Kim, Aerospace Engineer,
Mechanical Systems and Administrative Services Section, FAA, New York ACO
Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone
516-228-7300; email 9-avs-nyaco-cos@faa.gov.
SUPPLEMENTARY INFORMATION:

Comments Invited
The FAA invites you to send any written relevant data, views, or arguments about
this proposal. Send your comments to an address listed under ADDRESSES. Include
“Docket No. FAA-2022-1154; Project Identifier MCAI-2022-00550-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 Gabriel Kim,
Aerospace Engineer, Mechanical Systems and Administrative Services Section, FAA,
New York ACO Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
telephone 516-228-7300; email 9-avs-nyaco-cos@faa.gov. Any commentary that the

FAA receives which is not specifically designated as CBI will be placed in the public
docket for this rulemaking.
Background
Transport Canada Civil Aviation (TCCA), which is the aviation authority for
Canada, has issued TCCA AD CF-2022-20, dated April 19, 2022 (TCCA AD
CF-2022-20) (also referred to after this as the Mandatory Continuing Airworthiness
Information, or the MCAI), to correct an unsafe condition for all MHI RJ Aviation ULC
Model CL-600-2C10 (Regional Jet Series 700, 701 & 702) airplanes, Model
CL-600-2C11 (Regional Jet Series 550) airplanes, Model CL-600-2D15 (Regional Jet
Series 705) airplanes, Model CL-600-2D24 (Regional Jet Series 900) airplanes, and
Model CL-600-2E25 (Regional Jet Series 1000) airplanes. You may examine the MCAI
in the AD docket at regulations.gov by searching for and locating Docket No. FAA-20221154.
This proposed AD was prompted by a report that the pressure switch gauge
assembly for the cargo bay fire extinguisher container has the potential to display an
incorrect pressure under certain environmental conditions. The supplier attributed the
root cause of the container pressure display error to the use of a room temperature
vulcanizing (RTV) silicone. Both the HRD and LRD cargo bay fire extinguisher
containers are affected. The airplane is intended to be operated at temperatures as low as
-53.8 ℃ (-65 ℉). However, testing has shown that at temperatures below -49.4 ℃ (-57
℉), the RTV silicone goes through a glass transition that causes locking of the discharge
indication microswitch in a closed state (showing normal pressure) on 50% of the
assemblies tested. After returning to above -35.0 ℃ (-31.5 ℉) for more than 6 minutes,
the pressure switch gauge assembly returns to normal operation. The FAA is proposing
this AD to address instances where the fire extinguisher container capacity is reduced
below the level required to appropriately suppress a cargo fire and the flightcrew does not

receive an indication of low pressure, which, in the event of a fire in the cargo bay, could
lead to an uncontrollable fire and loss of the airplane. See the MCAI for additional
background information.
Related Service Information Under 1 CFR Part 51
MHI RJ Aviation ULC has issued Service Bulletin 670BA-26-013, dated October
8, 2021. This service information describes procedures for replacing the HRD and LRD
pressure switch gauge assemblies for the cargo bay fire extinguisher containers having
part number (P/N) 473919-1, P/N 473920-1 and P/N 474901-1, manufactured prior to
March 2020 as indicated on the identification plate, with a serviceable part number.
This service information 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
This product has been approved by the aviation authority of another country, and
is approved for operation in the United States. Pursuant to the FAA’s bilateral agreement
with the State of Design Authority, the FAA has been notified of the unsafe condition
described in the MCAI and service information referenced above. The FAA is proposing
this AD because the FAA evaluated all the relevant information and determined 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 accomplishing the actions specified in the
service information already described.

Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would affect 564
airplanes of U.S. registry. The FAA estimates the following costs to comply with this
proposed AD:
Estimated costs for required actions
Labor cost

Parts cost

Cost per product

Cost on U.S. operators

4 work-hours X $85
per hour = $340

$595

$935

$527,340

The FAA has included all known costs in its cost estimate. According to the
manufacturer, however, some or all 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 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
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
§ 39.13 [Amended]
2. The FAA amends § 39.13 by adding the following new airworthiness directive:
MHI RJ Aviation ULC (Type Certificate Previously Held by Bombardier, Inc.):
Docket No. FAA-2022-1154; Project Identifier MCAI-2022-00550-T.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive (AD) by
[INSERT DATE 45 DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL
REGISTER].
(b) Affected ADs
None.

(c) Applicability
This AD applies to all MHI RJ Aviation ULC Model CL-600-2C10 (Regional Jet
Series 700, 701 & 702) airplanes, Model CL-600-2C11 (Regional Jet Series 550)
airplanes, Model CL-600-2D15 (Regional Jet Series 705) airplanes, Model CL-600-2D24
(Regional Jet Series 900) airplanes, and Model CL-600-2E25 (Regional Jet Series 1000)
airplanes; certificated in any category.
(d) Subject
Air Transport Association (ATA) of America Code 26, Fire protection.
(e) Unsafe Condition
This AD was prompted by a report that the pressure switch gauge assembly for
the cargo bay fire extinguisher container has the potential to display an incorrect pressure
under certain environmental conditions. The FAA is issuing this AD to address instances
where the fire extinguisher container capacity is reduced below the level required to
appropriately suppress a cargo fire and the flightcrew does not receive an indication of
low pressure, which, in the event of a fire in the cargo bay, could lead to an
uncontrollable fire and loss of the airplane.
(f) Compliance
Comply with this AD within the compliance times specified, unless already done.
(g) Replacement
Within 10 years after the effective date of this AD: Replace the high rate of
discharge and low rate of discharge pressure switch gauge assemblies for any cargo bay
fire extinguisher container having part number (P/N) 473919-1, P/N 473920-1, and P/N
474901-1, manufactured prior to March 2020 as indicated on the identification plate, with
a serviceable part number, in accordance with the Accomplishment Instructions of MHI
RJ Aviation ULC Service Bulletin 670BA-26-013, dated October 8, 2021.

(h) Parts Installation Prohibition
As of 10 years after the effective date of this AD, or before further flight after the
replacement has been done in paragraph (g) of this AD, whichever occurs first, no person
may install, on any airplane, a cargo bay fire extinguisher container having P/N
473919-1, P/N 473920-1, or P/N 474901-1, manufactured prior to March 2020 as
indicated on the identification plate, unless “CW SB Fire Extinguisher-26-1” is identified
on the identification plate.
(i) No Return of Part Requirement
The Accomplishment Instructions of MHI RJ Aviation ULC Service Bulletin
670BA-26-013, dated October 8, 2021, specify to return the cargo fire extinguisher
containers to the manufacturer, this AD does not include that requirement.
(j) Other FAA AD Provisions
The following provisions also apply to this AD:
(1) Alternative Methods of Compliance (AMOCs): The Manager, New York ACO
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 certification office, send it to ATTN:
Program Manager, Continuing Operational Safety, FAA, New York ACO Branch, 1600
Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7300; fax 516-7945531. 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, New York ACO Branch, FAA; or Transport Canada Civil
Aviation (TCCA); or MHI RJ Aviation ULC’s TCCA Design Approval Organization

(DAO). If approved by the DAO, the approval must include the DAO-authorized
signature.
(k) Related Information
(1) Refer to Mandatory Continuing Airworthiness Information (MCAI) Transport
Canada Civil Aviation AD CF-2022-20, dated April 19, 2022, for related information.
This MCAI may be found in the AD docket on the Internet at regulations.gov by
searching for and locating Docket No. FAA-2022-1154.
(2) For more information about this AD, contact Gabriel Kim, Aerospace
Engineer, Mechanical Systems and Administrative Services Section, FAA, New York
ACO Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone
516-228-7300; email 9-avs-nyaco-cos@faa.gov.
(3) For service information identified in this AD, contact MHI RJ Aviation
Group, Customer Response Center, 3655 Ave. des Grandes-Tourelles, Suite 110,
Boisbriand, Québec J7H 0E2 Canada; North America toll-free telephone 833-990-7272
or direct-dial telephone 450-990-7272; fax 514-855-8501; email thd.crj@mhirj.com;
Internet mhirj.com. You may view this service information 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.
Issued on September 2, 2022.

Christina Underwood, Acting Director,
Compliance & Airworthiness Division,
Aircraft Certification Service.
[FR Doc. 2022-19448 Filed: 9/9/2022 8:45 am; Publication Date: 9/12/2022]