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###### Department of Transportation

###### Federal Aviation Administration

          - 14 CFR Part 39
          - [Docket No. FAA-2021-0784; Project Identifier MCAI-2020-01455-T]
          - RIN 2120-AA64

# AGENCY:

Federal Aviation Administration (FAA), DOT.

# ACTION:

Notice of proposed rulemaking (NPRM).

# 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 determination that new or more restrictive airworthiness limitations are necessary. 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 October 29, 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 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.                    

## 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-2021-0784; 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:

                        Elizabeth Dowling, 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-2021-0784; Project Identifier MCAI-2020-01455-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                           ( print page 51030)                        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 Elizabeth Dowling, 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.go.*                     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-2020-44, dated October 23, 2020 (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 on the internet at                     *https://www.regulations.gov*                     by searching for and locating Docket No. FAA-2021-0784.                

This proposed AD was prompted by a determination that new or more restrictive airworthiness limitations are necessary. The FAA is proposing this AD to address fatigue cracking and loss of structural integrity of the circumferential splice joint, which could result in reduced structural integrity of the airplane. See the MCAI for additional background 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 (a special detailed inspection for cracking of the skin circumferential splice at fuselage station (FS) 559.00, between stringer (STR) 10L and STR10R. 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 53-30-00-165*, “Special Detailed Inspection of the Skin Circumferential Splice at FS559.00 between STR10L and STR10R,” of Bombardier Challenger 605 CL-600-1A11 Time Limits/Maintenance Checks (TLMC), Product Support Publication (PSP) 605, Temporary Revision (TR) 5-163, dated April 30, 2020.
    - Task 53-30-00-188*, “Special Detailed Inspection of the Skin Circumferential Splice at FS559.00 between STR10L and STR10R,” of Bombardier Challenger CL-600-2A12 TLMC, PSP 601-5, TR 5-267, dated April 30, 2020.
    - Task 53-30-00-191*, “Special Detailed Inspection of the Skin Circumferential Splice at FS559.00 between STR10L and STR10R,” of Bombardier Challenger CL-600-2B16 TLMC, PSP 601A-5, TR 5-281, dated April 30, 2020.
    - Task 53-20-00-192*, “Special Detailed Inspection of the Skin Circumferential Splice at FS559.00 between STR10L and STR10R,” of Bombardier Challenger CL-600-2B16, CH 604, TLMC, Revision 32, dated December 18, 2019.
    - Task 53-20-00-192*, “Special Detailed Inspection of the Skin Circumferential Splice at FS559.00 between STR10L and STR10R,” of Bombardier Challenger CL-600-2B16, CH 605, TLMC, Revision 21, dated December 18, 2019.
    - Task 53-20-00-192*, “Special Detailed Inspection of the Skin Circumferential Splice at FS559.00 between STR10L and STR10R,” of Bombardier Challenger CL-600-2B16, CH 650, TLMC, Revision 8, 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 463 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 × $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.                          ( print page 51031)    

## 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

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

**Bombardier, Inc.:**                         Docket No. FAA-2021-0784; Project Identifier MCAI-2020-01455-T.                    

## (a) Comments Due Date

The FAA must receive comments on this airworthiness directive by October 29, 2021.

## (b) Affected ADs

None.

## (c) Applicability

This AD applies to Bombardier, Inc., airplanes, certificated in any category, identified in paragraphs (c)(1) through (3) of this AD.

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

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

(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 6049 inclusive, and 6050 through 6999 inclusive.

## (d) Subject

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

## (e) Reason

This AD was prompted by a determination that new or more restrictive airworthiness limitations are necessary. The FAA is issuing this AD to address fatigue cracking and loss of structural integrity of the circumferential splice joint, which could result in reduced structural integrity of the airplane.

## (f) Compliance

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

## (g) Maintenance or Inspection Program Revision

Within 60 days after the effective date of this AD, revise the existing maintenance or inspection program, as applicable, to incorporate the information 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 applicable document specified in Figure 1 to paragraph (g) of this AD, or within 60 days after the effective date of this AD, whichever occurs later.
      ( print page 51032)    

## (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 and 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                               ( print page 51033)                            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-2020-44, dated October 23, 2020, 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-2021-0784.                    

                        (2) For more information about this AD, contact Elizabeth Dowling, 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.*

                        (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.*                         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 8, 2021.

Lance T. Gant,

Director, Compliance & Airworthiness Division, Aircraft Certification Service.

BILLING CODE 4910-13-P

[FR Doc. 2021-19703 Filed 9-13-21; 8:45 am]

BILLING CODE 4910-13-C