DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0787; Project Identifier MCAI-2021-00252-T]
RIN 2120-AA64

Airworthiness Directives; Bombardier, Inc., Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD)
for certain Bombardier, Inc., Model CL-600-1A11 (600), CL-600-2A12
(601), and CL-600-2B16 (601-3A, 601-3R, and 604 Variants) airplanes.
This proposed AD was prompted by a report of a wing stall (wing drop/
un-commanded roll) during a landing flare. This proposed AD would
require revising the existing airplane flight manual (AFM) to
incorporate a limitation and procedure for the wing anti-ice (WAI)
system in order to mitigate the risk of ice accumulation on the wing
leading edges. 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 November 1,
2021.

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 https://www.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
Bombardier, Inc., 200 Cote-Vertu Road West, Dorval, Quebec
H4S 2A3, Canada; North America toll-free telephone 1-866-538-1247 or
direct-dial telephone 1-514-855-2999; email ac.yul@aero.bombardier.com;
internet https://www.bombardier.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 https://www.regulations.gov by
searching for and locating Docket No. FAA-2021-0787; 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: Chirayu Gupta, 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; fax 516-794-5531; 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-2021-0787; Project Identifier
MCAI-2021-00252-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
https://www.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
Chirayu Gupta, 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; fax 516-
794-5531; email 9-avs-nyaco-cos@faa.gov. 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 Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued TCCA AD CF-2021-06, dated February 26,
2021 (TCCA AD CF-2021-06) (also referred to after this as the Mandatory
Continuing Airworthiness Information, or the MCAI), to correct an
unsafe condition for certain Bombardier, Inc., Model CL-600-1A11 (600),
CL-600-2A12 (601), and CL-600-2B16 (601-3A, 601-3R, and 604 Variants)
airplanes. You may examine the MCAI in the AD docket at https://www.
regulations.gov by searching for and locating Docket No. FAA-2021-0787.

This proposed AD was prompted by a report of a wing stall (wing
drop/un-commanded roll) during a landing flare. Photographs after
landing showed that the airplane had mixed ice on the leading edges of
the wings; therefore, it was determined that during descent the
WAI system had been OFF because the ice detector did not detect ice.
Post-incident functional checks of the ice detectors revealed no faults
with the ice detector units onboard the aircraft. After the
investigation, it was revealed that the flightcrew had followed the AFM
procedures, which did not require the WAI system to be selected ON. The
FAA is proposing this AD to address ice accumulation on the wing
leading edges, which could result in a wing stall during landing and
consequent reduced controllability of the airplane. See the MCAI for
additional background information.

Related Service Information Under 1 CFR Part 51

Bombardier has issued the following service information, which
specifies a revised AFM limitation and procedure for the WAI system in
order to mitigate the risk of ice accumulation on the wing leading
edge. These documents are distinct since they apply to different
airplane configurations.

Sub-sub section (2), Wing Anti-ice System, of sub-section
I., Operation in Icing Conditions, of Chapter 3., OPERATION
LIMITATIONS, of the LIMITATIONS section; and sub-section C., Icing
Conditions During Flight, of Chapter 3., SYSTEMS OPERATIONS--ANTI-ICE,
and sub-section I., Before Landing, of Chapter 42., CONSOLIDATED CHECK
LIST, of NORMAL PROCEDURES section; of Canadair Challenger CL-600-1A11
AFM, Product Publication 600, Revision 114, dated April 16, 2020.

Sub-sub section (2), Wing Anti-ice System, of sub-section
I., Operation in Icing Conditions, of Chapter 4., OPERATION
LIMITATIONS, of the LIMITATIONS section; and sub-section C., Icing
Conditions During Flight, of Chapter 4., SYSTEMS OPERATIONS--ANTI-ICE,
and sub-section I., Before Landing, of Chapter 23., CONSOLIDATED CHECK
LIST, of the NORMAL PROCEDURES section; of Canadair Challenger CL-600-
1A11 AFM, Product Support Publication (PSP) 600-1, Revision 106, dated
April 16, 2020.

Sub-sub section (2), Wing Anti-ice System, of sub-section
I., Operation in Icing Conditions, of Chapter 3., OPERATING
LIMITATIONS, of the LIMITATIONS section; and sub-section E., Icing
Conditions During Flight, of Chapter 4., SYSTEMS OPERATIONS--ANTI-ICE,
of the NORMAL PROCEDURES section; of Canadair Challenger CL-600-2A12
AFM, PSP 601-1A, Revision 123, dated April 16, 2020.

Sub-sub section (2), Wing Anti-ice System, of sub-section
I., Operation in Icing Conditions, of Chapter 3., OPERATING
LIMITATIONS, of the LIMITATIONS section; and sub-section E., Icing
Conditions During Flight, of Chapter 4., SYSTEMS OPERATIONS--ANTI-ICE,
of the NORMAL PROCEDURES section; of Canadair Challenger CL-600-2A12
AFM, PSP 601-1A-1, Revision 82, dated April 16, 2020.

Sub-sub section (2), Wing Anti-ice System, of sub-section
I., Operation in Icing Conditions, of Chapter 3., OPERATING
LIMITATIONS, of the LIMITATIONS section; and sub-section E., Icing
Conditions During Flight, of Chapter 4., SYSTEMS OPERATIONS--ANTI-ICE,
of the NORMAL PROCEDURES section; of Canadair Challenger CL-600-2A12
AFM, PSP 601-1B, Revision 86, dated April 16, 2020.

Sub-sub section (2), Wing Anti-ice System, of sub-section
I., Operation in Icing Conditions, of Chapter 3., OPERATING
LIMITATIONS, of the LIMITATIONS section; and sub-section E., Icing
Conditions During Flight, of Chapter 4., SYSTEMS OPERATIONS--ANTI-ICE,
of the NORMAL PROCEDURES section; of Canadair Challenger CL-600-2A12
AFM, PSP 601-1B-1, Revision 84, dated April 16, 2020.

Sub-sub section (2), Wing Anti-ice System, of sub-section
I., Operation in Icing Conditions, of Chapter 3., OPERATING
LIMITATIONS, of the LIMITATIONS section; and sub-section E., Icing
Conditions During Flight, of Chapter 4., SYSTEMS OPERATIONS--ANTI-ICE,
of the NORMAL PROCEDURES section; of Canadair Challenger CL-600-2B16
AFM, PSP 601A-1, Revision 106, dated April 16, 2020.

Sub-sub section (2), Wing Anti-ice System, of sub-section
I., Operation in Icing Conditions, of Chapter 3., OPERATING
LIMITATIONS, of the LIMITATIONS section; and sub-section E., Icing
Conditions During Flight, of Chapter 4., SYSTEMS OPERATIONS--ANTI-ICE,
of the NORMAL PROCEDURES section; of Canadair Challenger CL-600-2B16
AFM, PSP 601A-1-1, Revision 95, dated April 16, 2020.

Sub-sub section B., Wing Anti-ice System, of sub-section
4., Operation in Icing Conditions, of Section 02-04, Operating
Limitations, of Chapter 2--LIMITATIONS; and sub-section M., Icing
Conditions During Flight, of Section 04-14, Ice and Rain Protection, of
Chapter 4--NORMAL PROCEDURES; of Bombardier Challenger 604 CL-600-2B16
AFM, PSP 604-1, Revision 116, dated December 18, 2019.

Sub-sub section B., Wing Anti-ice System, of sub-section
4., Operation in Icing Conditions, of Section 02-04, Operating
Limitations, of Chapter 2--LIMITATIONS; and sub-section M., Icing
Conditions During Flight, of Section 04-14, Ice and Rain Protection, of
Chapter 4--NORMAL PROCEDURES; of Bombardier Challenger 605 CL-600-2B16
AFM, PSP 605-1, Revision 54, dated December 18, 2019.

Sub-sub section B., Wing Anti-ice System, of sub-section
4., Operation in Icing Conditions, of Section 02-04, Operating
Limitations, of Chapter 2--LIMITATIONS; and sub-section M., Icing
Conditions During Flight, of Section 04-14, Ice and Rain Protection, of
Chapter 4--NORMAL PROCEDURES; of Bombardier Challenger 650 CL-600-2B16
AFM, PSP 650-1, Revision 19, dated December 18, 2019.

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 revising the existing AFM to
incorporate the limitations and procedures for the WAI system described
previously, in order to mitigate the risk of ice accumulation on the
wing leading edges, except as discussed under "Differences Between
this Proposed AD and the MCAI."

Differences Between This Proposed AD and the MCAI

This NPRM updates certain AFM revision levels identified in TCCA AD
CF-2021-06, and therefore identifies the complete, most recent service
information that will be incorporated by reference in the final rule.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 619 airplanes of U.S. registry. The FAA estimates the following
costs to comply with this proposed AD:

Estimated Costs for Required Actions

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.

Sec. 39.13 [Amended]

2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive: