(a) EFFECTIVE DATE

    This airworthiness directive (AD) is effective July 2, 2025.

(b) AFFECTED ADS

    This AD replaces AD 2020-19-13,  Amendment 39-21256 (85 FR 60887, Sep-
    tember 29, 2020) (AD 2020-19-13).

(c) APPLICABILITY

    This  AD  applies  to Bombardier, Inc., airplanes, identified in para-
    graphs (c)(1) through (3), certificated in any category, equipped with
    Scott (Avox/Zodiac) 5500  or 5600 series 11 cubic foot portable oxygen
    bottle(s) with upper bracket part number (P/N) 36758-02,  P/N 36758-12
    or P/N H3-2091-1 installed at the neck of the bottle(s).

(1) Model CL-600-1A11 (600) airplanes,  serial numbers (S/Ns) 1004 through
    1085 inclusive.

(2) Model CL-600-2A12 (601) airplanes, serial numbers 3001 through 3066 in
    -clusive.

(3) Model CL-600-2B16 (601-3A, 601-3R, and 604 Variants) airplanes, serial
    numbers 5001 through 5194 inclusive, 5301 through 5665 inclusive, 5701
    through 5988 inclusive, 6050 through 6119 inclusive, 6158, 6161, 6176,
    and 6181.

(d) SUBJECT

    Air Transport Association (ATA) of America Code 35, Oxygen.

(e) UNSAFE CONDITION

    This AD was prompted by a report  indicating that  the portable oxygen
    bottle installation's upper bracket latch assembly  can  catch  on the
    pressure gauge tube or on the pressure gauge bezel of the portable ox-
    ygen bottle.  This AD was also prompted by the determination that four
    additional Model CL-600-2B16 airplanes  may  be  subject to the unsafe
    condition. The FAA is issuing this AD to address the unsafe condition,
    which, if not addressed, could prevent fast  and  easy  access  to the
    portable oxygen bottle in an emergency situation.

(f) COMPLIANCE

    Comply with this AD within the compliance times specified,  unless al-
    ready done.

(g) RETAINED CHECK  FOR  AIRPLANES,  WITH REVISED FIGURE REFERENCE AND RE-
    VISED SERVICE INFORMATION

    This paragraph  restates the requirements of paragraph (g) of AD 2020-
    19-13,  with revised figure reference and revised service information.
    For airplanes  with a serial number  listed in Section 1.A. of the ap-
    plicable Bombardier service information specified in figure 1 to para-
    graph (g) of this AD, except airplane S/Ns 6158, 6161, 6176, and 6181:
    Within 60 months after November 3, 2020 (the effective date of AD 2020
    -19-13),  check each portable oxygen bottle installation  to determine
    the manufacturer and P/N,  in  accordance  with  paragraph 2.B. of the
    Accomplishment Instructions  of  the applicable Bombardier service in-
    formation specified in figure 1 to paragraph (g) of this AD.

         FIGURE 1 TO PARAGRAPH (G) - SERVICE INFORMATION REFERENCES
    ______________________________________________________________________
    AIRPLANE MODEL            BOMBARDIER SERVICE INFORMATION
    ______________________________________________________________________
    Model CL-600-1A11       Bombardier Service Bulletin 600-0772,
                            Revision 01, dated June 28, 2023

    Model CL-600-2A12       Bombardier Service Bulletin 601-0646,
                            Revision 01, dated June 28, 2023

    Model CL-600-2B16       Bombardier Service Bulletin 601-0646,
                            Revision 01, dated June 28, 2023

    Model CL-600-2B16       Bombardier Service Bulletin 604-35-006,
                            Revision 01, dated June 28, 2023

    Model CL-600-2B16       Bombardier Service Bulletin 605-35-005,
                            Revision 01, dated June 28, 2023

    Model CL-600-2B16       Bombardier Service Bulletin 650-35-001,
                            Revision 01, dated June 28, 2023
    ______________________________________________________________________


(h) RETAINED BRACKET MODIFICATION, WITH SPECIFIED COMPLIANCE TIME

    This paragraph  restates the requirements of paragraph (h) of AD 2020-
    19-13,  with a specified compliance time.  If,  during  the inspection
    specified in paragraph (g)  of this AD,  any portable oxygen bottle is
    found to be manufactured  by Scott (Avox/Zodiac) and is a 5500 or 5600
    series 11 cubic foot bottle, with upper bracket P/N 36758-02, 36758-12
    or H3-2091-1 installed  at the neck  of the bottle:  Within  60 months
    after November 3, 2020  (the effective date of AD 2020-19-13),  modify
    the portable oxygen bottle brackets  in accordance with paragraph 2.C.
    of the Accomplishment Instructions  of the applicable Bombardier serv-
    ice information specified in figure 1 to paragraph (g) of this AD.

(i) RETAINED CHECK  FOR AIRPLANES  NOT LISTED  IN THE SERVICE INFORMATION,
    WITH REVISED FIGURE REFERENCE AND REVISED SERVICE INFORMATION

    This paragraph restates  the requirements of paragraph (i) of AD 2020-
    19-13 with a revised figure reference and revised service information.
    For airplanes with a serial number  that is not listed in section 1.A.
    of the applicable Bombardier service information specified in figure 1
    to paragraph (g) of this AD, within 60 months  after  November 3, 2020
    (the effective date  of AD 2020-19-13),  check  each  portable  oxygen
    bottle installation  to determine the manufacturer and part number and
    accomplish corrective actions in accordance with the procedures speci-
    fied in paragraph (l)(1) of this AD.

(j) NEW CHECK REQUIREMENT FOR ADDED AIRPLANES

    For airplane S/Ns 6158, 6161, 6176, and 6181:  Within 60 months  after
    the effective date of this AD,  check  each portable oxygen bottle in-
    stallation to determine  the manufacturer  and  part number and accom-
    plish corrective actions  in  accordance with the procedures specified
    in paragraph (l)(1) of this AD.

(k) CREDIT FOR PREVIOUS ACTIONS

    This paragraph provides credit  for actions required by paragraphs (g)
    and (h) of this AD,  if those actions were performed before the effec-
    tive date of this AD using the applicable material  specified in para-
    graphs (k)(1) through (5) of this AD.

(1) Bombardier Service Bulletin 600-0772, dated June 29, 2018;

(2) Bombardier Service Bulletin 601-0646, dated June 29, 2018;

(3) Bombardier Service Bulletin 604-35-006, dated June 29, 2018;

(4) Bombardier Service Bulletin 605-35-005, dated June 29, 2018; and

(5) Bombardier Service Bulletin 650-35-001, dated June 29, 2018.

(l) ADDITIONAL AD PROVISIONS

(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 infor-
    mation directly to the manager of the International Validation Branch,
    mail it to the address  identified in paragraph (m)(1) of this AD. In-
    formation may be emailed to: AMOC@faa.gov.  Before using  any approved
    AMOC, notify your appropriate principal inspector,  or lacking a prin-
    cipal 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  accom-
    plished using a method approved by the Manager,  International Valida-
    tion 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.

(m) ADDITIONAL INFORMATION

(1) For more information about this AD,  contact Brenda Buitrago, Aviation
    Safety Engineer,  FAA,  1600 Stewart Avenue,  Suite 410,  Westbury, NY
    11590; telephone 516-228-7300; email 9-avs-nyaco-cos@faa.gov.

(2) Material identified in this AD  that is not incorporated  by reference
    is available at the address specified in paragraph (n)(3) of this AD.

(n) MATERIAL INCORPORATED BY REFERENCE

(1) The Director of the Federal Register  approved  the  incorporation  by
    reference  (IBR)  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 Service Bulletin 600-0772 Revision 01, dated June 28, 2023.

(ii) Bombardier Service Bulletin 601-0646 Revision 01 dated June 28, 2023.

(iii) Bombardier Service Bulletin 604-35-006, Revision 01,  dated June 28,
      2023.

(iv) Bombardier Service Bulletin 605-35-005,  Revision 01,  dated June 28,
     2023.

(v) Bombardier Service Bulletin 650-35-001,  Revision 01,  dated  June 28,
    2023.

(3) For Bombardier material identified in this AD, contact Bombardier Bus-
    iness Aircraft  Customer  Response  Center,  400 Cote-Vertu Road West,
    Dorval, Quebec H4S 1Y9, Canada;  telephone 514-855-2999; email 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 Admin-
    istration (NARA). For information on the availability of this material
    at NARA,  visit www.archives.gov/federal-register/cfr/ibr-locations or
    email fr.inspection@nara.gov.

Issued on April 3, 2025.  Steven W. Thompson, Acting Deputy Director, Com-
pliance & Airworthiness Division, Aircraft Certification Service.

FOR FURTHER INFORMATION CONTACT: Brenda Buitrago, Aviation Safety Engineer
FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 516-228
-7300; email 9-avs-nyaco-cos@faa.gov.