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 Department of Transportation Federal Aviation Administration 14 CFR Part 39
[Docket No. FAA-2024-1896; Project Identifier MCAI-2023-00978-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 MHI RJ Aviation ULC Model CL-600-2B19 (Regional Jet Series 100 and 440), CL-600-2C10 (Regional Jet Series 700, 701, and 702), CL-600-2C11 (Regional Jet Series 550), CL-600-2D15 (Regional Jet Series 705), CL-600-2D24 (Regional Jet Series 900), and CL-600-2E25 (Regional Jet Series 1000) airplanes. AD 2023-10-02 was prompted by the determination that radio altimeters cannot be relied on to perform their intended function if they experience interference from wireless broadband operations in the 3.7-3.98 GHz frequency band (5G C-Band). This AD was prompted by the determination that this interference can also result in certain failure messages being inhibited longer than intended. This proposed AD would require installing a new radio frequency (RF) bandpass filter on the coaxial line between the radio altimeter and the receive antenna in the aft equipment compartment. 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 24, 2024.
 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 
                        *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. *AD Docket:*
                         You may examine the AD docket at 
                        *regulations.gov*
                         under Docket No. FAA-2024-1896; 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, the mandatory continuing airworthiness information (MCAI), any comments received, and other information. The street address for Docket Operations is listed above. *Material Incorporated by Reference:* For MHI RJ material identified in this proposed AD, contact MHI RJ Aviation Group, Customer Response Center, 3655 Ave. des Grandes-Tourelles, Suite 110, Boisbriand, Québec J7H 0E2 Canada; North America toll-free telephone 833-990-7272 or direct-dial telephone 450-990-7272; fax 514-855-8501; email*thd.crj@mhirj.com*; website 
                        *mhirj.com*.
                    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.
 FOR FURTHER INFORMATION CONTACT: Steven Dzierzynski, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7300; 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-2024-1896; Project Identifier MCAI-2023-00978-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 
                    *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 Steven Dzierzynski, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7300; 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.
                    ( print page 73010) Background The FAA issued AD 2023-10-02, Amendment 39-22438 (88 FR 34065, May 26, 2023) (AD 2023-10-02) to address the effect of interference from wireless broadband operations in the 5G C-Band on all transport and commuter category airplanes equipped with a radio altimeter. AD 2023-10-02 was prompted by a determination that radio altimeters cannot be relied upon to perform their intended function if they experience interference from wireless broadband operations in the 5G C-Band. AD 2023-10-02 requires revising the limitations section of the existing airplane flight manual to incorporate limitations prohibiting transport and commuter category airplanes from performing certain low-visibility landing operations at any airport unless they have upgraded their radio altimeters. Transport Canada, which is the aviation authority for Canada, issued corresponding Transport Canada AD CF-2023-46, dated June 30, 2023, to require similar limitations on flight operations requiring radio altimeter data in U.S. airspace affected by 5G C-Band wireless signals. Additionally, Transport Canada has issued Transport Canada AD CF-2023-62R1, dated November 21, 2023 (referred to as “the MCAI”), for certain serial-numbered MHI RJ Aviation ULC Model CL-600-2B19 (Regional Jet Series 100 and 440), CL-600-2C10 (Regional Jet Series 700, 701, and 702), CL-600-2C11 (Regional Jet Series 550), CL-600-2D15 (Regional Jet Series 705), CL-600-2D24 (Regional Jet Series 900), and CL-600-2E25 (Regional Jet Series 1000) airplanes. The MCAI states that, in addition to the effects of 5G C-Band broadband interference identified in FAA AD 2023-10-02, MHI RJ has determined that 5G C-Band broadband interference can result in certain failure messages and aural alerts being inhibited longer than intended. Specifically, this can result in the inhibition of hydraulic system #3 and wing anti-ice overheat failure messages such that flightcrew are unable to perform appropriate airplane flight manual (AFM) procedures in the time needed to prevent loss of elevator control due to hydraulic system overheat and wing structural damage due to wing anti-ice system overheat. This condition, if not corrected, could result in delayed flightcrew response leading to loss of continued safe flight and landing. The MCAI requires the installation of a new RF bandpass filter on the coaxial line between the radio altimeter and the receive antenna in the aft equipment compartment. For airplanes with a dual radio altimeter configuration, the MCAI requires a filter to be installed on both systems or on one system provided the second system is deactivated. When the airplane is modified as specified in the MCAI, the configuration with the RF bandpass filter installed has been determined to be “radio altimeter tolerant.” The actions of the MCAI apply only to airplanes operating within the contiguous U.S. airspace. The FAA is proposing this AD because radio altimeter anomalies can result in the inhibition of certain failure messages such that the flightcrew are unable to perform appropriate AFM procedures in the time needed to prevent loss of elevator control due to hydraulic system overheat and wing structural damage due to wing anti-ice system overheat, possibly resulting in delayed flightcrew response leading to loss of continued safe flight and landing. You may examine the MCAI in the AD docket at 
                    *regulations.gov*
                     under Docket No. FAA-2024-1896. Material Incorporated by Reference Under 1 CFR Part 51 The FAA reviewed MHI RJ Service Bulletins 601R-34-152, Revision D, dated May 11, 2023, and 670BA-34-054, dated February 20, 2023. This material specifies procedures for installing a new RF bandpass filter on the coaxial line between the radio altimeter and the receive antenna in the aft equipment compartment. These documents are distinct since they apply to different airplane models. This material 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 this State of Design Authority, it has notified the FAA of the unsafe condition described in the material referenced above. The FAA is issuing this NPRM after determining that 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 accomplishing the actions specified in the material already described. This AD would not apply to airplanes that have been modified to be a radio altimeter tolerant airplane under the requirements of AD 2023-10-02. Differences Between the MCAI and This NPRM Although the actions of the MCAI apply only to Canadian-registered airplanes operating within the contiguous U.S. airspace, this proposed AD would apply to U.S.-registered airplanes operating in any airspace. The FAA has determined that the expansion of 5G C-band has occurred in other countries, such as Canada and Brazil, in which 5G C-band interference is expected. Costs of Compliance The FAA estimates that this AD, if adopted as proposed, would affect up to 873 airplanes of U.S. registry. However, many of these airplanes may already have a bandpass filter installed in compliance with AD 2023-10-02 and would not have any costs because of this proposed AD. The FAA estimates the following costs to comply with this proposed AD: Estimated Costs
Labor cost
Parts cost
Cost per 
                             product
Cost on U.S.
                             operators58 work-hours × $85 per hour = $4,930
$53,647
$58,577
Up to $51,137,721.
 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 
                    ( print page 73011)
                    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. § 39.13
 2.The FAA amends § 39.13 by adding the following new airworthiness directive: **MHI RJ Aviation ULC (Type Certificate Previously Held by Bombardier Inc.):**
                         Docket No. FAA-2024-1896; Project Identifier MCAI-2023-00978-T. (a) Comments Due Date The FAA must receive comments on this airworthiness directive (AD) by October 24, 2024. (b) Affected ADs None. (c) Applicability This AD applies to the MHI RJ Aviation ULC (Type Certificate previously held by Bombardier Inc.) airplanes identified in paragraphs (c)(1) through (6) of this AD, certificated in any category, that are equipped with a radio altimeter and not determined to be a radio altimeter tolerant airplane as defined in paragraph (g) of this AD. (1) Model CL-600-2B19 (Regional Jet Series 100 and 440) airplanes, serial number (S/N) 7002 through 8113. (2) Model CL-600-2C10 (Regional Jet Series 700, 701, and 702) airplanes, S/N 10002 through 10999. (3) Model CL-600-2C11 (Regional Jet Series 550) airplanes, S/N 10002 through 10999. (4) Model CL-600-2D15 (Regional Jet Series 705) airplanes, S/N 15001 through 15990. (5) Model CL-600-2D24 (Regional Jet Series 900) airplanes, S/N 15001 through 15990. (6) Model CL-600-2E25 (Regional Jet Series 1000) airplanes, S/N 19013 through 19990. (d) Subject Air Transport Association (ATA) of America Code 34, Navigation. (e) Unsafe Condition This AD was prompted by the determination that radio altimeters cannot be relied upon to perform their intended function if they experience interference from wireless broadband operations in the 3.7-3.98 GHz frequency band (5G C-Band). The FAA is issuing this AD because radio altimeter anomalies can result in the inhibition of certain failure messages such that the flightcrew are unable to perform appropriate airplane flight manual procedures in the time needed to prevent loss of elevator control due to hydraulic system overheat and wing structural damage due to wing anti-ice system overheat, possibly resulting in delayed flightcrew response leading to loss of continued safe flight and landing. (f) Compliance Comply with this AD within the compliance times specified, unless already done. (g) Definitions For purposes of this AD, a “radio altimeter tolerant airplane” is one for which the radio altimeter, as installed, demonstrates the tolerances specified in paragraphs (g)(1) and (2) of this AD, using a method approved by the FAA. No actions are required by this AD for radio altimeter tolerant airplanes. (1) Tolerance to radio altimeter interference, for the fundamental emissions (3.7-3.98 GHz), at or above the power spectral density (PSD) curve threshold specified in figure 1 to paragraph (g)(1) of this AD. Figure 1 to Paragraph (g)(1)—Fundamental Effective Isotropic PSD at Outside Interface of Airplane Antenna 
 
  (2) Tolerance to radio altimeter interference, for the spurious emissions (4.2-4.4 GHz), at or above the PSD curve threshold specified in figure 2 to paragraph (g)(2) of this AD. Figure 2 to Paragraph (g)(2)—Spurious Effective Isotropic PSD at Outside Interface of Airplane Antenna 
 
  (h) Filter Installation: Model CL-600-2B19 For Model CL-600-2B19 airplanes: Within 2,300 flight hours or 12 months after the effective date of this AD, whichever occurs first, install a radio frequency (RF) bandpass filter on each radio altimeter in accordance with the applicable parts of the Accomplishment Instructions in MHI RJ Service Bulletin 601R-34-152, Revision D, dated May 11, 2023. Alternatively, airplanes with a dual radio altimeter configuration may comply with this paragraph by installing an RF bandpass filter on one radio altimeter and deactivating the second radio altimeter in accordance with the applicable parts of the Accomplishment Instructions in MHI RJ Service Bulletin 601R-34-152, Revision D, dated May 11, 2023. (i) Filter Installation: Model CL-600-2C10, CL-600-2C11, CL-600-2D15, and CL-600-2D24 For Model CL-600-2C10, CL-600-2C11, CL-600-2D15, and CL-600-2D24 airplanes: Within 2,100 flight hours or 12 months after the effective date of this AD, whichever occurs first, install an RF bandpass filter on each radio altimeter in accordance with the applicable parts of the Accomplishment Instructions in MHI RJ Service Bulletin 670BA-34-054, dated February 20, 2023. Alternatively, airplanes with a dual radio altimeter configuration may comply with this paragraph by installing an RF bandpass filter on one radio altimeter and deactivating the second radio altimeter in accordance with the applicable parts of the Accomplishment Instructions in MHI RJ Service Bulletin 670BA-34-054, dated February 20, 2023. (j) Filter Installation: Model CL-600-2E25 For Model CL-600-2E25 airplanes: Before the next flight in the contiguous U.S. airspace after the effective date of this AD, install an RF bandpass filter on each radio altimeter in accordance with the applicable parts of the Accomplishment Instructions in MHI RJ Service Bulletin 670BA-34-054, dated February 20, 2023.
                        ( print page 73014) (k) Credit for Previous Actions For Model CL-600-2B19 airplanes: This paragraph provides credit for the actions required by paragraph (h) of this AD, if those actions were performed before the effective date of this AD using the material in paragraphs (k)(1) through (4) of this AD, provided the electrical idents for coax cables are installed using Part G of the Accomplishment Instructions in MHI RJ Service Bulletin 601R-34-152, Revision D, dated May 11, 2023, within the compliance time specified in paragraph (h) of this AD. (1) MHI RJ Service Bulletin 601R-34-152, dated February 14, 2023. (2) MHI RJ Service Bulletin 601R-34-152, Revision A, dated February 28, 2023. (3) MHI RJ Service Bulletin 601R-34-152, Revision B, dated March 28, 2023. (4) MHI RJ Service Bulletin 601R-34-152, Revision C, dated April 20, 2023. (l) Additional AD Provisions The following provisions also apply to this AD: (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 information directly to the manager of the International Validation Branch, mail it to the address identified in paragraph (m) of this AD. Information may be emailed to: 
                        *9-AVS-NYACO-COS@faa.gov*. 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, International Validation Branch, FAA; or Transport Canada; or MHI RJ Aviation ULC's Transport Canada Design Approval Organization (DAO). If approved by the DAO, the approval must include the DAO-authorized signature. (m) Additional Information For more information about this AD, contact Steven Dzierzynski, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7300; email 
                        *9-avs-nyaco-cos@faa.gov*. (n) Material Incorporated by Reference (1) The Director of the Federal Register approved the incorporation by reference 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) MHI RJ Service Bulletin 601R-34-152, Revision D, dated May 11, 2023. (ii) MHI RJ Service Bulletin 670BA-34-054, dated February 20, 2023. (3) For MHI RJ material identified in this AD, contact MHI RJ Aviation Group, Customer Response Center, 3655 Ave. des Grandes-Tourelles, Suite 110, Boisbriand, Québec J7H 0E2 Canada; North America toll-free telephone 833-990-7272 or direct-dial telephone 450-990-7272; fax 514-855-8501; email 
                        *thd.crj@mhirj.com*; website 
                        *mhirj.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 Administration (NARA). For information on the availability of this material at NARA, visit 
                        *www.archives.gov/federal-register/cfr/ibr-locationsoremailfr.inspection@nara.gov*. Issued on August 28, 2024. Victor Wicklund, Deputy Director, Compliance & Airworthiness Division, Aircraft Certification Service.


[FR Doc. 2024-20244 Filed 9-5-24; 11:15 am] BILLING CODE 4910-13-P