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PROPOSED AD BOMBARDIER, INC.: Docket No. FAA-2020-1181; Project Identifier MCAI-2020-01368-T.
(a) COMMENTS DUE DATE

    The FAA  must receive  comments on  this airworthiness  directive (AD)
    action by May 3, 2021.

(b) AFFECTED AIRWORTHINESS DIRECTIVES (ADS)

    None.

(c) APPLICABILITY

    This AD applies to all Bombardier, Inc.,  Model CL-600-1A11 (600), CL-
    600-2A12 (601) and CL-600-2B16 (601-3A, 601-3R, and 604 Variants) air-
    planes, certificated in any category.

(d) SUBJECT

    Air Transport Association (ATA) of America Code 05, Time Limits/Main-
    tenance Checks.

(e) REASON

    This AD  was prompted  by reports  of corrosion  on the passenger door
    internal  structure  of  in-service  airplanes.  This  AD  was further
    prompted by a determination that new or more restrictive airworthiness
    limitations  are necessary.  The FAA  is  issuing  this AD  to address
    corrosion on the passenger door internal structure and consequent loss
    of the structural integrity of the forward passenger door.

(f) COMPLIANCE

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

(g) MAINTENANCE OR INSPECTION PROGRAM REVISION

    Within  30  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  time
    limits/maintenance checks  (TLMC) revision  specified in  figure 1  to
    paragraph (g) of  this AD. The  initial compliance time  for doing the
    tasks is at the  time specified in the  TLMC, or within 30  days after
    the effective date of this AD, whichever occurs later.

                    FIGURE 1 TO PARAGRAPH (G)  TLMC REVISIONS
    ______________________________________________________________________
    AIRPLANE MODEL   TLMC TASK NO.     TASK TITLE        TLMC MANUAL NO.
    ______________________________________________________________________
    CL-600-1A11      53-10-01-101*¹    Upper Latch       Product Support
    (CL-600)                           Pins of the       Publication (PSP)
                                       Passenger Door    605, Revision 39,
                                                         dated January 8,
                                                         2018

    CL-600-2A12      53-10-01-101*¹    Upper Latch       PSP 601-5,
    (CL-601)                           Pins of the       Revision 46,
                                       Passenger Door    dated January 8,
                                                         2018

    CL-600-2B16      53-10-01-101*¹    Upper Latch       PSP 601A-5,
    (CL 601 3A/3R)                     Pins of the       Revision 42,
                                       Passenger Door    dated January 8,
                                                         2018

    CL-600-2B16      53-20-00-188*¹    Special De-       CH 604 TLMC,
    (CL 604)                           tailed Inspec-    Revision 32,
                                       tion of the       dated December
                                       Upper Latch       18, 2019
                                       Pins of the
                                       Passenger Door

    CL-600-2B16      53-20-00-188*¹    Special De-       CH 605 TLMC,
    (CL605²)                           tailed Inspec-    Revision 21,
                                       tion of the       dated December
                                       Upper Latch       18, 2019
                                       Pins of the
                                       Passenger Door
    ______________________________________________________________________
    ¹The asterisk  (or "one star")  with the last three digits of the task
    number indicates that the task is an airworthiness limitation task.

    ²Model CL-600-2B16 (604 Variant),  referred to by the marketing desig-
    nation CL-605.
    ______________________________________________________________________

(h) NO ALTERNATIVE ACTIONS OR 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 or intervals,
    are  approved  as  an  alternative  method  of  compliance  (AMOC)  in
    accordance with the procedures  specified in paragraph (i)(1)  of this
    AD.

(i) 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 516-794-5531.  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  Bombardier
    Inc.'s TCCA  Design Approval  Organization (DAO).  If approved  by the
    DAO, the approval must include the DAO-authorized signature.

(j) RELATED INFORMATION

(1) Refer   to   Mandatory  Continuing  Airworthiness  Information  (MCAI)
    Canadian  AD  CF-2016-37,  dated   November  25,  2016,  for   related
    information. This MCAI may be found  in the AD docket on the  internet
    at https://www.regulations.gov  by searching  for and  locating Docket
    No. FAA-2020-1181.

(2) For more information about this AD, contact Aziz Ahmed, Aerospace Eng-
    ineer, Airframe and Propulsion Section, FAA, New York ACO Branch, 1600
    Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7329;
    fax 516-794-5531; email 9-avs-nyaco-cos@faa.gov.

(3) For service information  identified  in this AD,  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 http://www.
    bombardier.com. You may view this service information at the FAA, Air-
    worthiness 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 January 20, 2021. Lance T Gant, Director, Compliance & Airworth-
iness Division, Aircraft Certification Service.

DATES: The FAA must receive comments on this proposed AD by May 3, 2021.
PREAMBLE 

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-1181; Project Identifier MCAI-2020-01368-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-600-1A11 (600), CL-600-2A12 (601),
and CL-600-2B16 (601-3A, 601-3R and 604 Variants) airplanes. This
proposed AD was prompted by reports of corrosion on the passenger door
internal structure of in-service airplanes. 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 May 3,
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 http://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 on the internet at https://www.regulations.
gov by searching for and locating Docket No. FAA-2020-1181;
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: Aziz Ahmed, Aerospace Engineer,
Airframe and Propulsion Section, FAA, New York ACO Branch, 1600 Stewart
Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7329; 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-2020-1181; Project Identifier
MCAI-2020-01368-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 proposed AD.

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 Aziz
Ahmed, Aerospace Engineer, Airframe and Propulsion Section, FAA, New
York ACO Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
telephone 516-228-7329; fax 516-794-5531; 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.

Discussion

Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued Canadian AD CF-2016-37, dated November
25, 2016 (also referred to after this as the Mandatory Continuing
Airworthiness Information, or the MCAI), to correct an unsafe condition
for all 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 on the internet at https://www.
regulations.gov by searching for and locating Docket No. FAA-2020-1181.

This proposed AD was prompted reports of corrosion on the passenger
door internal structure of in-service airplanes caused by an
accumulation of moisture under the epoxy ramp. 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 corrosion on the
passenger door internal structure and consequent loss of the structural
integrity of the forward passenger door. See the MCAI for additional back-
ground information.

Related Service Information Under 1 CFR Part 51

The FAA reviewed the following Bombardier service information,
which describes new or more restrictive airworthiness limitations for
the upper latch pins of the forward passenger door. These documents are
distinct since they apply to different airplane configurations. (Note:
The asterisk (or "one star") with the last three digits of the task
number indicates that the task is an airworthiness limitation task.)

Task 53-10-01-101*, "Upper Latch Pins of the Passenger
Door," of Bombardier Challenger CL-600-1A11 Time Limits/Maintenance
Checks (TLMC), Product Support Publication (PSP) 605, Revision 39,
dated January 8, 2018.

Task 53-10-01-101*, "Upper Latch Pins of the Passenger
Door," of Bombardier Challenger CL-600-2A12 TLMC, PSP 601-5, Revision
46, dated January 8, 2018.

Task 53-10-01-101*, "Upper Latch Pins of the Passenger
Door," of Bombardier Challenger CL-600-2B16 TLMC, PSP 601A-5, Revision
42, dated January 8, 2018.

Task 53-20-00-188*, "Special Detailed Inspection of the
Upper Latch Pins of the Passenger Door," of Bombardier Challenger
TLMC, CH 604 TLMC, Revision 32, dated December 18, 2019.

Task 53-20-00-188*, "Special Detailed Inspection of the
Upper Latch Pins of the Passenger Door," of Bombardier Challenger
TLMC, CH 605 TLMC, Revision 21, 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 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 proposed AD affects 133 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

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: