AC 20-199 Appendix B Figure B-3. RF Interference Test Setup Subassembly B.4 RA Transceiver RFI Injection Test.
The RA system must meet the measurement validity, accuracy, and noise when injecting RFI into the RF or TX ports of the RA transceiver with a conducted power level calculated using equation B-1 of this AC:
(Equation B-1) 𝐵𝑊 × 106 𝑐𝑃𝑡𝑒𝑠𝑡(𝑓𝑐) = 𝑃𝐹𝐷 (𝑓𝑐 ± ) + 30 − 10 × log10(4𝜋) + 20 × log10 ( )+ 𝐺(𝑓2 𝑓 𝑐)𝑐 + 10 × log10(𝐵𝑊) − 𝐿𝑐𝑜𝑎𝑥 Where:
𝑃𝑡𝑒𝑠𝑡(𝑓𝑐) = input power at RA Transceiver TX or RX port, in dBm 𝑃𝐹𝐷(𝑓) = power flux-density specified in table 2-1 at the frequency 𝑓, in dBW/m2/MHz 𝑐 = speed of light, in meters per second 𝑓𝑐 = center frequency of waveform specified in table B-1, in Hz 𝐺(𝑓𝑐) = assumed RA antenna gain at the frequency 𝑓𝑐, in dBi 𝐵𝑊 = bandwidth of waveform specified table B-1, in MHz 𝐿𝑐𝑜𝑎𝑥 = coaxial cable loss between the RA antenna and the RA transceiver, in dB Note 1: The assumed antenna gain is the gain specified in the RA transceiver IM that is sufficient to maintain the required RA performance.
Note 2: For RFI injection testing into the TX port, the coaxial cable loss is the minimum required cable loss in the TX path specified in the RA transceiver IM. For RFI injection testing into the RX port, the coaxial cable loss in is the minimum required cable loss in the RX path as specified in the RA transceiver IM.
B-3
AC 20-199 Appendix B B.5 RF Filter Subassembly (RFFSA) and RA Transceiver RFI Injection Test.
If the RFI injection testing is performed using separate tests of an RFFSA and a transceiver subassembly, the measurement validity, accuracy, and noise must meet the requirements with the test levels at the RF port of the transceiver subassembly calculated using either equation B-2 of this AC, if the RFFSA is tested with continuous waveform (CW) only, or equation B-3 of this AC, if the RFFSA is tested with the same waveforms as the transceiver subassembly.
(Equation B-2) 𝐵𝑊 𝐵𝑊𝑃𝑇𝑋𝑅(𝑓𝑐, 𝑊𝑛) = 𝑃𝑡𝑒𝑠𝑡(𝑓𝑐, 𝑊𝑛) − min [𝐹𝐷𝑅(𝑓𝑐 − ) , 𝐹𝐷𝑅(𝑓𝑐 + )]2 2 Where:
𝑃𝑇𝑋𝑅(𝑓𝑐, 𝑊𝑛)= input power at transceiver subassembly TX or RX port, in dBm 𝑃𝑡𝑒𝑠𝑡(𝑓𝑐, 𝑊𝑛) = test level at input port of RFFSA calculated from equation B-1, in dBm 𝐹𝐷𝑅(𝑓) = RFFSA frequency-dependent rejection at frequency 𝑓 measured with CW, in dB 𝑓𝑐 = center frequency of waveform 𝑊𝑛, as specified in table B-1, in MHz 𝐵𝑊 = bandwidth of waveform 𝑊𝑛, as specified in table B-1, in MHz (Equation B-3) 𝑃𝑇𝑋𝑅(𝑓𝑐, 𝑊𝑛) = 𝑃𝑡𝑒𝑠𝑡(𝑓𝑐, 𝑊𝑛) − 𝐹𝐷𝑅(𝑓𝑐, 𝑊𝑛) Where:
𝑃𝑇𝑋𝑅(𝑓𝑐, 𝑊𝑛)= input power at transceiver subassembly TX or RX port, in dBm 𝑃𝑡𝑒𝑠𝑡(𝑓𝑐, 𝑊𝑛) = test level at input port of RFFSA calculated from equation B-1, in dBm 𝐹𝐷𝑅(𝑓𝑐, 𝑊𝑛) = RFFSA frequency-dependent rejection at frequency 𝑓𝑐 measured with waveform 𝑊𝑛, in dB 𝑓𝑐 = center frequency of waveform 𝑊𝑛, as specified in table B-1, in MHz Table B-1. RFI Test Waveforms Frequency 3000-4100 MHz 4100-4200 MHz 4200-4400 MHz 4400-4500 MHz 4500-5600 MHz Waveform 2 3 1 3 2 B-4
AC 20-199 Appendix B B.6 RFI Test Waveforms.
1. Band-limited additive white Gaussian noise (AWGN) fully within the 4.2-4.4 GHz frequency band with a minimum bandwidth of 99 percent of the actual bandwidth of the transceiver unit under test (UUT) (a maximum bandwidth of 200 MHz), a minimum peak-to-average power ratio (PAPR) of 10 dB, and a 100 percent duty cycle.
2. Band-limited AWGN fully outside of the 4.2-4.4 GHz frequency band with a minimum bandwidth of 100 MHz, minimum PAPR of 10 dB, and 100 percent duty cycle.
3. Band -limited AWGN fully outside of the 4.2-4.4 GHz frequency band with a minimum bandwidth of 10 MHz, minimum PAPR of 10 dB, and 100 percent duty cycle.
Note 1: The ITM average power represents the constraining scenario from an RFI compatibility perspective. However, to fully characterize the RA performance, peak power testing should be considered to capture data to support any future applications.
Note 2: If testability constraints are encountered for waveform 2, a reduced PAPR may also be acceptable for testing that exceeds the average power to meet an equivalent peak power (i.e., over test of the average power). These methods demonstrate that the RA system can meet or exceed both the ITM average power and any peak power spikes simultaneously.
B.7 RFI Test Altitudes.
Simulated HAGL greater than 10 ft and less than or equal to 75 ft.
Simulated HAGL greater than 75 ft and less than or equal to 200 ft.
Simulated HAGL greater than 200 ft and less than or equal to 500 ft.
Note 1: The test loop losses at each altitude should include the worst-case loop loss in accordance with TSO-C87().
Note 2: RA performance requirements for operations above 500 ft HAGL are not addressed in § 91.220(b). Up to 500 ft represents the constraining scenario for the RA equipment and is critical for compatibility with the RFI environment. However, to fully characterize the RA performance, it is recommended to test using simulated HAGL greater than or equal to 500 ft, less than or equal to 2500 ft, greater than 2500 ft, and up to and just above the maximum HAGL of the RA to capture data to support any future applications.
B.8 RFI Testing with Multiplex Installations.
The ITM specified in table 2-1 of this AC must be met in the presence of all aircraft RA systems (i.e., dual or triple installations).
B-5
AC 20-199 Appendix B B.9 Environmental Degradation.
The ITM specified in table 2-1 of this AC must be met, accounting for any degradation in performance due to the operating environment. The temperature of the equipment has an impact on performance, so the demonstration should be conducted at the maximum equipment operating temperature.
B.10 UUT and Test Equipment Tolerances.
The testing should account for unit-to-unit variations in the UUT and test equipment uncertainty.
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AC 20-199 Appendix C APPENDIX C. RELATED MATERIAL Note: The regulations and guidance should be applicable to the aircraft or design change certification basis or to a later revision.
C.1 Title 14, Code of Federal Regulations (14 CFR).
The following 14 CFR regulations are related to this AC. You can download the full text of these regulations from the Federal Register website at http://www.ecfr.gov/.
• § 23.2335, Lightning protection.
• § 23.2500, Airplane level systems requirements.
• § 23.2505, Function and installation.
• § 23.2510, Equipment, systems, and installations.
• § 23.2515, Electrical and electronic system lightning protection.
• § 23.2520, High-intensity Radiated Fields (HIRF) protection.
• § 23.2600, Flightcrew interface.
• § 23.2605, Installation and operation.
• § 23.2610, Instrument markings, control markings, and placards.
• § 23.2615, Flight, navigation, and powerplant instruments.
• § 23.2620, Airplane flight manual.
• § 23.1529, Instructions for Continued Airworthiness.
• § 25.777, Cockpit controls.
• § 25.581, Lightning protection.
• § 25.1301, Function and installation.
• § 25.1302, Installed systems and equipment for use by the flightcrew.
• § 25.1309, Equipment, systems, and installations.
• § 25.1310, Power source capacity and distribution.
• § 25.1316, Electrical and electronic system lightning protection.
• § 25.1317, High-intensity Radiated Fields (HIRF) Protection.
• § 25.1321, Arrangement and visibility.
• § 25.1322, Flightcrew alerting.
• § 25.1329, Flight guidance system.
• § 25.1331, Instruments using a power supply.
• § 25.1333, Instrument systems.
• § 25.1351, General.
• § 25.1431, Electronic equipment.
• § 25.1529, Instructions for Continued Airworthiness.
• § 27.610, Lightning and static electricity protection.
• § 27.777, Cockpit controls.
• § 27.1301, Function and installation.
• § 27.1303, Flight and navigation instruments.
• § 27.1309, Equipment, systems, and installations.
• § 27.1316, Electrical and electronic system lightning protection.
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AC 20-199 Appendix C
• § 27.1317, High-intensity Radiated Fields (HIRF) Protection.
• § 27.1321, Arrangement and visibility.
• § 27.1322, Warning, caution, and advisory lights.
• § 27.1329, Automatic pilot and flight guidance system.
• Part 27, Appendix B / 29.1431.
• § 27.1529, Instructions for Continued Airworthiness.
• § 29.610, Lightning and static electricity protection.
• § 29.777, Cockpit controls.
• § 29.1301, Function and installation.
• § 29.1303, Flight and navigation instruments.
• § 29.1309, Equipment, systems, and installations.
• § 29.1316, Electrical and electronic system lightning protection.
• § 29.1317, High-intensity Radiated Fields (HIRF) Protection.
• § 29.1321, Arrangement and visibility.
• § 29.1322, Warning, caution, and advisory lights.
• § 29.1329, Automatic pilot and flight guidance system.
• § 29.1331, Instruments using a power supply.
• § 29.1333, Instrument systems.
• § 29.1351, General.
• § 29.1431, Electronic equipment.
• § 29.1529, Instructions for Continued Airworthiness.
• § 91.220, Radio Altimeter Systems.
• § 135.160, Radio altimeters for rotorcraft operations.
C.2 FAA Advisory Circulars.
The following ACs are related to the guidance in this AC. The latest version of each AC referenced in this document is available on the FAA website at FAA Advisory Circulars and on the Dynamic Regulatory System (DRS).
• AC 20-73A, Aircraft Ice Protection.
• AC 20-115D, Airborne Software Development Assurance Using EUROCAE ED- 12() and RTCA DO-178().
• AC 20-131A, Airworthiness Approval of Traffic Alert and Collision Avoidance Systems (TCAS II) and Mode S Transponders.
• AC 20-136B, Aircraft Electrical and Electronic System Lightning Protection.
• AC 20-138D, Airworthiness Approval of Positioning and Navigation Systems.
• AC 20-151C, Airworthiness Approval of Traffic Alert and Collision Avoidance Systems (TCAS II), Versions 7.0 & 7.1 and Associated Mode S Transponders.
• AC 20-152A, Development Assurance for Airborne Electronic Hardware.
• AC 20-155A, Industry Documents to Support Aircraft Lightning Protection Certification.
• AC 20-158B, The Certification of Aircraft Electrical and Electronic Systems for Operation in the High-Intensity Radiated Fields (HIRF) Environment.
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AC 20-199 Appendix C
• AC 20-167B, Airworthiness Approval of Enhanced Vision System, Enhanced Flight Vision System, and Combined Vision System Equipment.
• AC 20-175, Controls for Flight Deck Systems.
• AC 20-185A, Airworthiness Approval of Synthetic Vision Systems, Synthetic Vision Guidance Systems and Aircraft State Awareness Synthetic Vision Systems.
• AC 20-190, Aircraft Electromagnetic Compatibility Certification.
• AC 21-16G, RTCA Document DO-160 versions D, E and F, “Environmental Conditions and Test Procedures for Airborne Equipment.”
• AC 21-46A, Technical Standard Order Program.
• AC 21-50, Installation of TSOA Articles and LODA Appliances.
• AC 23-8C, Flight Test Guide for Certification of Part 23 Airplanes.
• AC 23-17C, Systems and Equipment Guide for Certification of Part 23 Airplanes and Airships.
• AC 23-18, Installation of Terrain Awareness and Warning System (TAWS) Approved for Part 23 Airplanes.
• AC 23.1309-1E, System Safety Analysis and Assessment for Part 23 Airplanes.
• AC 23.1311-1C, Installation of Electronic Display in Part 23 Airplanes.
• AC 25-7D, Flight Test Guide for Certification of Transport Category Airplanes.
• AC 25-11B, Electronic Flight Displays.
• AC 25-12, Airworthiness Criteria for the Approval of Airborne Windshear Warning Systems in Transport Category.
• AC 25-23, Airworthiness Criteria for the Installation Approval of a Terrain Awareness and Warning System (TAWS) for Part 25 Airplanes.
• AC 25.1302-1, Installed Systems and Equipment for Use by the Flightcrew.
• AC 25.1309-1B, System Design and Analysis.
• AC 25.1322-1, Flightcrew Alerting.
• AC 25.1329-1C, Approval of Flight Guidance Systems.
• AC 25.1701-1, Certification of Electrical Wiring Interconnection Systems on Transport Category Airplanes.
• AC 27-1B, Certification of Normal Category Rotorcraft.
• AC 29-2C, Certification of Transport Category Rotorcraft.
• AC 120-28D, Criteria for Approval of Category III Weather Minima for Takeoff, Landing, and Rollout.
• AC 120-29A, Criteria for Approval of Category I and Category II Weather Minima for Approach.
• AC 120-118, Criteria for Approval/Authorization of all Weather Operations for Takeoff, Landing, and Rollout.
C.3 FAA Technical Standard Orders.
The following TSOs are related to the guidance in this AC. The latest version of each AC referenced in this document is available on the Dynamic Regulatory System (DRS).
• TSO-C63g, Airborne Weather Radar Equipment.
• TSO-C87(), Airborne Low-Range Radio Altimeter.
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AC 20-199 Appendix C
• TSO-C117b, Airborne Windshear Warning and Escape Guidance Systems for Transport Airplanes.
• TSO-C118a, Traffic Alert and Collision Avoidance System (TCAS) Airborne Equipment, TCAS I.
• TSO-C119e, Traffic Alert and Collision Avoidance System (TCAS) Airborne Equipment, TCAS II With Hybrid Surveillance.
• TSO-C151d, Terrain Awareness and Warning Systems (TAWS).
• TSO-C164a, Night Vision Goggles.
• TSO-C194, Helicopter Terrain Awareness and Warning System (HTAWS).
• TSO-C198, Automatic Flight Guidance and Control System (AFGCS) Equipment.
• TSO-C209, Electronic Flight Instrument System (EFIS) Display.
• TSO-C219a, Airborne Collision Avoidance System (ACAS) Xa/Xo.
• TSO-C221, Airborne Low-Range Radio Altimeter Transceiver.
• TSO-C222, Airborne Low-Range Radio Altimeter Antenna.
• TSO-C223, Airborne Low-Range Radio Altimeter Display.
C.4 FAA Airworthiness Directives.
The following Airworthiness Directives (AD) are related to the guidance in this AC and are available on the Federal Register website at https://www.federalregister.gov/.
• AD 2023-10-02, Transport and Commuter Category Airplanes, Amendment 39-22438, 88 FR 34065 (May 26, 2023), https://www.federalregister.gov/documents/2023/05/26/2023-11371/airworthinessdirectives-transport-and-commuter-category-airplanes.
• AD 2023-11-07, Various Helicopters, Amendment 39-22453, 88 FR 40685 (June 22, 2023), https://www.federalregister.gov/documents/2023/06/22/2023- 13319/airworthiness-directives-various-helicopters.
C.5 FAA Policy Statements.
The following Policy Statement is related to the guidance in this AC. The latest version is available on the FAA website at FAA Policy Statements and on the Dynamic Regulatory System (DRS).
• PS-AIR-21.16-02, Establishment of Special Conditions for Aircraft Systems Information Security Protection.
C.6 EASA Cer tification Specifications.
The following Certification Specifications (CS) are related to the guidance in this AC.
The latest version is available on the EASA website at https://www.easa.europa.eu/home.
• Certification Specifications for European Technical Standard Orders (CS-ETSO).
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AC 20-199 Appendix C C.7 European Union Aviation Safety Agency (EASA).
The following Acceptable Means of Compliance (AMC) are related to the guidance in this AC. The latest version of each AMC referenced in this document is available on the EASA website at https://www.easa.europa.eu/home.
• Acceptable Means of Compliance and Guidance Material to Annex IV (Part-CAT) and Annex V (Part-SPA) of Commission Regulation (EU) No 965/2012 of 5 October 2012, and later amendments.
• Acceptable Means of Compliance for Airworthiness of Products, Parts and Appliances (AMC-20), AMC 20-42 “Airworthiness information security risk assessment”.
C.8 ASTM Consensus Standards.
FAA-accepted consensus standards for part 23 normal category airplanes, including any required changes for acceptance, are available online at https://www.faa.gov/aircraft/air_cert/design_approvals/small_airplanes/small_airplanes _regs.
• F3061, Standard Specification for Systems and Equipment in Small Aircraft.
• F3117, Standard Specification for Crew Interface in Aircraft.
• F3233, Standard Specification for Instrumentation in Small Aircraft.
• F3367, Standard Practice for Simplified Methods for Addressing High-Intensity Radiated Fields (HIRF) and Indirect Effects of Lightning on Aircraft.
• F3532, Standard Practice for Protection of Aircraft Systems from Intentional Unauthorized Electronic Interactions.
C.9 RTCA.
The following RTCA (formerly Radio Technical Commission for Aeronautics) documents are related to the guidance in this AC. Unless otherwise specified, use the latest FAA-accepted revision for guidance. If the document is revised after publication of this AC, you should verify that the FAA accepts the subsequent revision or update as an acceptable form of guidance. This document can be ordered online at https://www.rtca.org.
• DO-152A, Development Assurance for Airborne Electronic Hardware.
• DO-155A, Minimum Performance Standards Airborne Low-Range Radar Altimeters.
• DO-160G, Environmental Conditions and Test Procedures for Airborne Equipment.
• DO-161A, Minimum Performance Standards-Airborne Ground Proximity Warning Equipment.
• DO-174, Development of Civil Aircraft and Systems.
• DO-178C, Software Consideration in Airborne Systems and Equipment Certification.
• DO-185B, Minimum Operational Performance Standards for Traffic Alert and Collision Avoidance System II (TCAS II) Airborne Equipment.
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AC 20-199 Appendix C
• DO-197A, Minimum Operational Performance Standards for an Active Traffic Alert and Collision Avoidance System I (Active TCAS I).
• DO-220B, Minimum Operational Performance Standards (MOPS) For Airborne Weather Radar Systems.
• DO-254, Design Assurance Guidance for Airborne Electronic Hardware.
• DO-300A, Minimum Operational Performance Standards (MOPS) for Traffic Alert and Collision Avoidance System II (TCASII) Hybrid Surveillance.
• DO-309, Minimum Operational Performance Standards (MOPS) for Helicopter Terrain Awareness and Warning System (HTAWS) Airborne Equipment.
• DO-315B, Minimum Aviation System Performance Standards (MASPS) for Enhanced Vision Systems, Synthetic Vision Systems, Combined Vision Systems and Enhanced Flight Vision Systems.
• DO-325, Minimum Operation Performance Standards (MOPS) for Automatic Flight Guidance and Control Systems and Equipment.
• DO-326B, Airworthiness Security Process Specification.
• DO-355A, Information Security Guidance for Continuing Airworthiness.
• DO-356A, Airworthiness Security Methods and Considerations.
• DO-359, Minimum Aviation System Performance Standards (MASPS) for Synthetic Vision Guidance Systems.
• DO-367, Minimum Operational Performance Standards (MOPS) for Terrain Awareness and Warning Systems (TAWS) Airborne Equipment.
• DO-376, Minimum Operational Performance Standard for Offshore Helicopter Terrain Awareness and Warning System (HTAWS).
• DO-385A, Minimum Operational Performance Standards for Airborne Collision Avoidance System X (ACAS X) (ACAS Xa and ACAS Xo).
• DO-391, Aeronautical Information System Security Framework Guidance.
• DO-392, Guidance for Security Event Management.
• DO-405, Minimum Operating Performance Standard (MOPS) for Helicopter Terrain Awareness Warning System (HTAWS) for Onshore Helicopter Operations.
C.10 European Organization for Civil Aviation Equipment (EUROCAE).
The following EUROCAE documents are related to the guidance in this AC. Unless otherwise specified, use the latest FAA-accepted revision for guidance. If the document is revised after publication of this AC, you should verify that the FAA accepts the subsequent revision or update as an acceptable form of guidance. The documents are available online at https://www.eurocae.net.
• ED-14G, Environmental Conditions and Test Procedures for Airborne Equipment.
• ED-30, MPS for Airborne Low Range Radio (radar) Altimeter Equipment.
• ED-202B, Airworthiness Security Process Specification.
• ED-203A, Airworthiness Security Methods and Considerations.
• ED-204A, Information Security Guidance for Continuing Airworthiness.
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AC 20-199 Appendix C C.11 Society of Automotive Engineers (SAE) International.
The following SAE Aerospace Recommended Practice (ARP) documents are related to the guidance in this AC. Unless otherwise specified, use the latest FAA-accepted revision for guidance. If the document is revised after publication of this AC, you should verify that the FAA accepts the subsequent revision or update as an acceptable form of guidance. The documents are available online at https://www.sae.org.
• AS6296, Electronic Flight Instrument System (EFIS).
• AS8034B, Minimum Performance Standard for Airborne Multipurpose Electronic Displays.
• ARINC 707-7, Radio Altimeter.
• ARP4102-7, Electronic Displays.
• ARP4754B, Guidelines for Development of Civil Aircraft and Systems.
• ARP4761A, Guidelines for Conducting the Safety Assessment Process on Civil Aircraft, Systems, and Equipment.
C.12 International Civil Aviation Organization (ICAO).
• ICAO Doc 9718, Handbook on Radio Frequency Spectrum Requirements for Civil Aviation.
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AC 20-199 Appendix D APPENDIX D. DEFINITION OF KEY TERMS The following definitions apply for the purpose of this AC:
D.1 Decision Height (DH).
See 14 CFR 1.1, General Definitions.
Note: During operation of the approach procedure, the RA system is the only source of determining (or annunciating) when the decision height has been reached.
D.2 Electrical Height Output.
The reported RA quantity from the RA system provided as an electrical output interface signal. Note: The output interface may be analog or digital.
D.3 Height Above Ground Level (HAGL).
The distance from the portion of aircraft structure in which the RA antenna(s) is/are installed to the terrain surface at a given point along a flight path.
D.4 In-Band Radio Frequency Interference (RFI).
External RFI signals within the RA operating frequency (4.2–4.4 GHz).
D.5 Installation Time Delay.
The actual round-trip RF signal propagation time delay in an RA system installation on an aircraft relative to the desired zero-height reference point. This may include, for example, the propagation delays in the coaxial cables or transmission lines between the RA transceiver and the RA antenna(s), and the free-space propagation from the RA antenna(s) to the terrain surface when the aircraft is on the ground with the main landing gear touching in a pre-established aircraft attitude (i.e., nose gear may not be touching).
D.6 Installation Height Offset.
A value, determined by calibration, configuration, or installation of the RA system, which defines a constant bias to be subtracted from the measurement result of the RA transceiver in order to account for the height of the RA antenna(s) above the terrain while the aircraft is on the ground (with the main landing gear touching in a preestablished aircraft attitude, the length of coaxial cables or transmission lines between the RA transceiver, and the RA antenna(s) and any other system delays as needed).
D-1