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###### Department of Transportation

###### Federal Aviation Administration

          - 14 CFR Part 39
          - [Docket No. FAA-2020-1181; Project Identifier MCAI-2020-01368-T; Amendment 39-21617; AD 2021-13-12]
          - RIN 2120-AA64

# AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

# ACTION:

Final rule.

# SUMMARY:

The FAA is adopting 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 AD was prompted by reports of corrosion on the passenger door internal structure of in-service airplanes. This AD requires revising the existing maintenance or inspection program, as applicable, to incorporate new or more restrictive airworthiness limitations. The FAA is issuing this AD to address the unsafe condition on these products.

# DATES:

This AD is effective September 9, 2021.

The Director of the Federal Register approved the incorporation by reference of certain publications listed in this AD as of September 9, 2021.

# ADDRESSES:

                        For service information identified in this final rule, contact Bombardier, Inc., 200 Côte-Vertu Road West, Dorval, Québec 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. It is also available on the internet at                         *https://www.regulations.gov*                         by searching for and locating Docket No. FAA-2020-1181.                    

## 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 final rule, any comments received, and other information. The address for Docket Operations is U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.                

# 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:

## Background

                    Transport Canada Civil Aviation (TCCA), which is the aviation authority for Canada, has issued TCCA AD CF-2016-37, dated November 25, 2016 (also referred to 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.                

                    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to all Bombardier, Inc., Model CL-600-1A11 (600), CL-600-2A12 (601), and CL-600-2B16 (601-3A, 601-3R and 604 Variants) airplanes. The NPRM published in the                     **Federal Register**                     on March 17, 2021 (86 FR 14551). The NPRM was prompted by reports of corrosion on the passenger door internal structure of in-service airplanes caused by an accumulation of moisture under the epoxy ramp. The NPRM proposed to require revising the existing maintenance or inspection program, as applicable, to incorporate new or more restrictive airworthiness limitations. 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. See the MCAI for additional background information.                

## Comments

The FAA gave the public the opportunity to participate in developing this final rule. The FAA received no comments on the NPRM or on the determination of the cost to the public.

## Conclusion

The FAA reviewed the relevant data and determined that air safety and the public interest require adopting this final rule as proposed, except for minor editorial changes. The FAA has determined that these minor changes:
    - Are consistent with the intent that was proposed in the NPRM for addressing the unsafe condition; and
    - Do not add any additional burden upon the public than was already proposed in the NPRM.

## 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.                

## Costs of Compliance

The FAA estimates that this AD affects 133 airplanes of U.S. registry. The FAA estimates the following costs to comply with this 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                           ( print page 42702)                        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 × $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

This AD will not have federalism implications under Executive Order 13132. This AD will 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 that this AD:

(1) Is not a “significant regulatory action” under Executive Order 12866,

(2) Will not affect intrastate aviation in Alaska, and

(3) Will 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

## Adoption of the Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 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 

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

**2021-13-12 Bombardier, Inc.:**                             Amendment 39-21617; Docket No. FAA-2020-1181; Project Identifier MCAI-2020-01368-T.                        

## (a) Effective Date

This airworthiness directive (AD) is effective September 9, 2021.

## (b) Affected 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) airplanes, certificated in any category.

## (d) Subject

Air Transport Association (ATA) of America Code 05, Time Limits/Maintenance 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.
      ( print page 42703)    

## (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) TCCA 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 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.*

## (k) Material Incorporated by Reference

(1) The Director of the Federal Register approved the incorporation by reference (IBR) of the service information listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.

(2) You must use this service information as applicable to do the actions required by this AD, unless this AD specifies otherwise.

(i) 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.

(ii) 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.

(iii) 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.

                            (iv) Task 53-20-00-188 *, “Special Detailed Inspection of the Upper Latch Pins                                   ( print page 42704)                                of the Passenger Door,” of Bombardier Challenger TLMC, CH 604 TLMC, Revision 32, dated December 18, 2019.                        

(v) 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.

                            (3) For service information identified in this AD, contact Bombardier, Inc., 200 Côte-Vertu Road West, Dorval, Québec 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.*

(4) 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.

                            (5) You may view this service information that is incorporated by reference at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, email                             *fedreg.legal@nara.gov,*                             or go to:                             *https://www.archives.gov/​federal-register/​cfr/​ibr-locations.html.*

Issued on June 16, 2021.

Lance T. Gant,

Director, Compliance & Airworthiness Division, Aircraft Certification Service.

BILLING CODE 4910-13-P

BILLING CODE 4910-13-C

[FR Doc. 2021-16565 Filed 8-4-21; 8:45 am]