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###### Department of Transportation

###### Federal Aviation Administration

          - 14 CFR Part 25
          - [Docket No. FAA-2021-0484; Special Conditions No. 25-794-SC]

# AGENCY:

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

# ACTION:

Final special conditions; request for comments.

# SUMMARY:

                        These special conditions are issued for a supplemental type certificate on certain transport category airplanes. These airplanes, as modified by Learjet, Inc. (Learjet), will have a novel or unusual design feature when compared to the state of technology envisioned in the airworthiness standards for transport-category airplanes. This design feature is the installation of a system that allows connection to airplane electronics and networks, and access from aircraft external sources (                        *e.g.,*                         operator networks, wireless devices, internet connectivity, service provider satellite communications, electronic flight bags, etc.) to the previously isolated airplane electronic assets (networks, systems, and databases). The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. These special conditions contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards.                    

# DATES:

This action is effective on Learjet on January 12, 2022. Send comments on or before February 28, 2022.

# ADDRESSES:

Send comments identified by Docket No. FAA-2021-0484 using any of the following methods:
      -  Federal eRegulations Portal:                          Go to                          https://www.regulations.gov/​                          and follow the online instructions for sending your comments electronically.                    
      -  Mail:                          Send comments to Docket Operations, M-30, U.S. Department of Transportation (DOT), 1200 New Jersey Avenue SE, Room W12-140, West Building Ground Floor, Washington, DC 20590-0001.                    
      -  Hand Delivery or Courier:                          Take comments to Docket Operations in Room W12-140 of the West Building Ground Floor at 1200 New Jersey Avenue SE, Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.                    
      -  Fax:                          Fax comments to Docket Operations at 202-493-2251.                    

*Privacy:*                         Except for Confidential Business Information (CBI) as described in the following paragraph, and other information as described in title 14, Code of Federal Regulations (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 FAA will also post a report summarizing each substantive verbal contact received about these special conditions.                    

*Confidential Business Information:*                         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 these special conditions contain commercial or financial information that is customarily treated as private, that you actually treat as private, and that is relevant or responsive to these special conditions, 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 the indicated comments will not be placed in the public docket of these special conditions. Send submissions containing CBI to the person indicated in the Contact section below. Comments the FAA receives, which are not specifically designated as CBI, will be placed in the public docket for this rulemaking.                    

*Docket:*                         Background documents or comments received may be read at                         *https://www.regulations.gov/​*                         at any time. Follow the online instructions for accessing the docket or go to Docket Operations in Room W12-140 of the West Building Ground Floor at 1200 New Jersey Avenue SE, Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.                    

# FOR FURTHER INFORMATION CONTACT:

                        Varun Khanna, Aircraft Information Systems Section, AIR-622, Technical Innovation Policy Branch, Policy and Innovation Division, Aircraft Certification Service, Federal Aviation Administration, 2200 South 216th Street, Des Moines, Washington 98198; telephone and fax 206-231-3159; email                         *varun.khanna@faa.gov.*

# SUPPLEMENTARY INFORMATION:

                    The substance of these special conditions has been published in the                     **Federal Register**                     for public comment in several prior instances with no substantive comments received. Therefore, the FAA finds, pursuant to § 11.38(b), that new comments are unlikely, and notice and comment prior to this publication are unnecessary.                

## Comments Invited

The FAA invites interested people to take part in this rulemaking by sending written comments, data, or views. The most helpful comments reference a specific portion of the special conditions, explain the reason for any recommended change, and include supporting data.

The FAA will consider all comments received by the closing date for comments. The FAA may change these special conditions based on the comments received.

## Background

On May 15, 2020, Learjet applied for a supplemental type certificate to install an Aircraft Health Management System (AHMS) in the airplanes listed on the approved model list (AML) for STC No. ST01970WI. These airplanes are super-midsize-category business jets with maximum passenger capacity of 16. These airplanes have a maximum takeoff weight of 38,850 pounds.

## Type Certification Basis

                    Under the provisions of 14 CFR 21.101, Learjet must show that airplanes for which they make application to modify by STC no. ST01970WI, as changed, continue to meet the applicable provisions of the regulations                           ( print page 1663)                        listed in each airplane's respective type certificate or the applicable regulations in effect on the date of application for the change, except for earlier amendments as agreed upon by the FAA.                

                    If the Administrator finds that the applicable airworthiness regulations (                    *e.g.,*14 CFR part 25) do not contain adequate or appropriate safety standards for the listed airplanes because of a novel or unusual design feature, special conditions are prescribed under the provisions of § 21.16.                

Special conditions are initially applicable to the models for which they are issued. Should the applicant apply for a supplemental type certificate to modify any other models included on the same type certificate to incorporate the same novel or unusual design feature, these special conditions would also apply to the other models under § 21.101.

In addition to the applicable airworthiness regulations and special conditions, the airplanes listed in the AML must comply with the fuel-vent and exhaust-emission requirements of 14 CFR part 34, and the noise-certification requirements of 14 CFR part 36.

The FAA issues special conditions as defined in § 11.19, in accordance with § 11.38, and they become part of the type certification basis under § 21.101.

## Novel or Unusual Design Features

The airplanes listed on the AML in STC no. ST01970WI will incorporate the following novel or unusual design features:

                    The installation of an AHMS that allows connection to airplane electronics and networks, and access from aircraft external sources (                    *e.g.,*                     operator networks, wireless devices, internet connectivity, service provider satellite communications, electronic flight bags, etc.) to the previously isolated airplane electronic assets (networks, systems, and databases).                

## Discussion

The architecture and network configuration of the airplanes listed on the AML of STC no. ST01970WI are novel or unusual for commercial transport airplanes because they may allow increased connectivity to and access from external network sources, airline operations, and maintenance networks to the airplanes' control domain and airline information-services domain. The airplanes' control domain and airline information-services domain perform functions required for the safe operation and maintenance of the airplanes. Previously, these domains had very limited connectivity with external network sources. This data network and design integration creates a potential for unauthorized persons to access the aircraft-control domain and airline information-services domain, and presents security vulnerabilities related to the introduction of computer viruses and worms, user errors, and intentional sabotage of airplane electronic assets (networks, systems, and databases) critical to the safety and maintenance of the airplanes.

                    The existing FAA regulations did not anticipate these networked airplane-system architectures. Furthermore, these regulations and the current guidance material do not address potential security vulnerabilities, which could be exploited by unauthorized access to airplane networks, data buses, and servers. Therefore, these special conditions ensure that the security (                    *i.e.,*                     confidentiality, integrity, and availability) of airplane systems is not compromised by unauthorized wired or wireless electronic connections. This includes ensuring that the security of the airplanes' systems is not compromised during maintenance of airplane electronic systems. These special conditions also require the applicant to provide appropriate instructions to the operator to maintain all electronic-system safeguards that have been implemented as part of the original network design, so that this feature does not allow or reintroduce security threats.                

These special conditions contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards.

## Applicability

As discussed above, these special conditions are applicable to airplanes listed in the AML of STC no. ST01970WI. Should Learjet apply at a later date for another STC, to include another airplane model with the same novel or unusual design feature, these special conditions would also apply to that model as well. These special conditions are not applicable to those airplane models for which special conditions for protection from unauthorized external access have already been issued to the type certificate for those specific models.

These special conditions are only applicable to design changes applied for after its effective date.

## Conclusion

This action affects only a certain novel or unusual design feature for airplane models listed on the AML of STC no. ST01970WI, as modified by Learjet. It is not a rule of general applicability and affects only the applicant.

# List of Subjects in 14 CFR Part 25

      - Aircraft
      - Aviation safety
      - Reporting and recordkeeping requirements

## Authority Citation

The authority citation for these special conditions is as follows:

Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701, 44702, 44704.

## The Special Conditions

▪ Accordingly, pursuant to the authority delegated to me by the Administrator, the following special conditions are issued as part of the type certification basis for airplane models listed on the approved model list of supplemental type certificate no. ST01970WI, as modified by Learjet.

1. The applicant must ensure airplane electronic-system security protection from access by unauthorized sources external to the airplane, including those possibly caused by maintenance activity.

2. The applicant must ensure that electronic-system security threats are identified and assessed, and that effective electronic-system security-protection strategies are implemented to protect the airplane from all adverse impacts on safety, functionality, and continued airworthiness.

3. The applicant must establish appropriate procedures to allow the operator to ensure that continued airworthiness of the airplane is maintained, including all post-type-certification modifications that may have an impact on the approved electronic-system security safeguards.

Issued in Kansas City, Missouri, on January 6, 2022.

Patrick R. Mullen,

Manager, Technical Innovation Policy Branch, Policy and Innovation Division, Aircraft Certification Service.

[FR Doc. 2022-00390 Filed 1-11-22; 8:45 am]

BILLING CODE 4910-13-P