DME Specification FAA-E-37016 - Approved 2025-06-24.pdf

FAA-E-37016

June 24, 2025

SUPERSEDING

FAA-E-2996

April 1, 2008

U.S. Department of Transportation

Federal Aviation Administration

PERFORMANCE SPECIFICATION

DISTANCE MEASURING EQUIPMENT (DME)

TRANSPONDER SYSTEM

ii 06/24/2025

FOREWORD

1. This specification is approved for use by all Departments of the Federal Aviation Administration (FAA).

2. This specification defines the minimum requirements for the Distance Measuring Equipment (DME) Transponder System.

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Table of Contents

1. INTRODUCTION

1.1 SCOPE

1.2 OVERVIEW

2. APPLICABLE DOCUMENTS

2.1 GENERAL

2.2 GOVERNMENT DOCUMENTS

2.2.1 FAA Specifications, Standards and Handbooks

2.2.2 Other Government Documents, Drawings and Publications

2.3 NON-GOVERNMENT PUBLICATIONS

2.4 ORDER OF PRECEDENCE

3. REQUIREMENTS

3.1 GENERAL REQUIREMENTS

3.1.1 System Characteristics

3.1.2 Interlock Signal from the Instrument Landing System (ILS)

3.1.3 Integrity of Signal

3.1.4 Assigned Channel Assurance

3.1.5 Environmental Operating Conditions

3.1.5.1 NON-OPERATING CONDITIONS

3.1.5.2 OPERATING CONDITIONS

3.1.5.3 LIGHTNING PROTECTION

3.1.6 Electromagnetic Interference (EMI) / Electromagnetic Compatibility (EMC)

3.2 TRANSPONDER

3.2.1 Operating Channels

3.2.1.1 BROADBAND OPERATION

3.2.1.2 RF TUNING

3.2.1.3 CHANNEL FREQUENCY AND STABILITY

3.2.2 Duplexer

3.2.3 Receiver and Associated Circuitry

3.2.3.1 RECEIVER BANDWIDTH AND STABILITY

3.2.3.2 RECEIVER DECODER

3.2.3.3 RECEIVER DEAD TIME

3.2.3.4 RECEIVER RECOVERY TIME

3.2.3.5 ECHO SUPPRESSION

3.2.3.6 RECEIVER SENSITIVITY

3.2.3.7 INTERFERENCE SUPPRESSION

3.2.3.8 SQUITTER

3.2.3.9 AUTOMATIC GAIN REDUCTION (AGR)

3.2.3.10 PRIORITY OF TRANSMISSION

3.2.4 Identification Signals and Keying

3.2.4.1 IDENTIFICATION SIGNAL

3.2.4.2 IDENTIFICATION KEYING SOURCE

3.2.4.3 INDEPENDENT IDENTIFICATION SIGNAL CHARACTERISTICS

3.2.4.4 ASSOCIATED IDENTIFICATION SIGNAL CHARACTERISTICS

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3.2.4.5 IDENTIFICATION KEYING CONTROL

3.2.5 Transmitter and Associated Circuitry

3.2.5.1 TRANSMISSION RATE

3.2.5.2 TUNING AND SPURIOUS OUTPUT

3.2.5.3 TRANSPONDER POWER OUTPUT

3.2.5.4 RF OUTPUT POWER CONTROL

3.2.5.5 REPLY DELAY VALUES AND ADJUSTMENTS

3.2.5.6 ACCURACY

3.2.6 Transponder Output Signals

3.2.6.1 PULSE SHAPE

3.2.6.2 PULSE CODING

3.2.6.3 DELAY TIME VARIATION

3.2.6.4 PULSE POWER VARIATION

3.2.6.5 RF PULSE SIGNAL SPECTRUM

3.2.6.6 OUT-OF-BAND SPURIOUS RADIATION

3.2.6.7 INTER-PULSE OUTPUT LEVEL

3.2.6.8 RETRIGGERING OF TRANSPONDER

3.2.7 Stabilization of Performance Characteristics

3.2.8 Duty Cycle Overload Protection

3.2.9 Thermal Overload Protection

3.2.10 Performance Upon Fault Condition of RF Equipment Output Circuit

3.3 ANTENNA

3.3.1 Antenna Types

3.3.2 Frequency Range

3.3.3 Polarization

3.3.4 Characteristic Impedance and VSWR

3.3.5 Antenna Gain

3.3.6 Vertical Pattern

3.3.7 Horizontal Pattern

3.3.7.1 OMNI-DIRECTIONAL TYPE

3.3.7.2 UNI-DIRECTIONAL TYPE

3.3.7.3 BI-DIRECTIONAL TYPE

3.3.8 Radome and Weatherproofing

3.3.9 Antenna Mount

3.3.10 Monitor Probes

3.3.11 Antenna Cables

3.3.12 Obstruction Lights

3.3.13 Power Handling

3.3.14 Grounding

3.4 MONITOR

3.4.1 Operating Channels

3.4.1.1 BROADBAND OPERATION

3.4.1.2 RF TUNING

3.4.1.3 FREQUENCY STABILITY

3.4.2 RF Input Levels

3.4.3 Coupling Probe Inputs

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3.4.3.1 DME ANTENNA

3.4.3.2 TRANSMISSION LINE DIRECTIONAL COUPLER

3.4.4 Interrogation Signal Generator

3.4.4.1 OPERATIONAL MODES

3.4.4.2 PULSE SYNCHRONIZATION OUTPUT

3.4.4.3 RF OUTPUT PULSE SIGNAL

3.4.4.4 PULSE CODING

3.4.4.5 PULSE POWER VARIATION

3.4.4.6 DETECTED RF OUTPUT SIGNAL

3.4.4.7 RF PULSE SPECTRUM

3.4.4.8 SPURIOUS OUTPUT

3.4.4.9 TEST RF OUTPUT FREQUENCY

3.4.4.10 RF OUTPUT LEVEL CALIBRATION

3.4.4.11 RF OUTPUT LEVEL AND ACCURACY

3.4.5 Transponder Monitor

3.4.5.1 MONITOR ALARM ACTION

3.4.5.2 MONITORED PARAMETERS

3.4.5.3 TEST SIGNALS AND MONITORING ACTIVITIES

3.4.5.4 TRANSPONDER TESTS

3.4.5.5 MONITOR ALARM LIMIT CERTIFICATION TESTS

3.4.5.6 MONITOR INTERROGATOR DATA

3.4.5.7 MONITOR FAILSAFE

3.5 CONTROL, STATUS AND INDICATOR FUNCTIONS

3.5.1 Front Panel

3.5.1.1 CONTROLS

3.5.1.2 STATUS AND INDICATORS

3.5.2 Maintenance Data Terminal (MDT) Software

3.5.3 Remote Control

3.5.4 Fault History

3.5.5 Fault Diagnostics

3.5.6 Trend Analysis Data Collection and Storage

3.5.7 Automatic Reset Function

3.6 REMOTE MAINTENANCE MONITORING (RMM)

3.6.1 Remote Monitoring Subsystem (RMS)

3.6.1.1 RMS FUNCTIONS

3.6.2 Alarm and Alert Messages

3.6.2.1 ALARMS

3.6.2.2 MAINTENANCE ALERTS

3.6.3 Non-Volatile Data Storage

3.6.4 RMS Data Sampling Rate

3.6.5 Spare Input/Output Capacity

3.6.6 Environmental Monitoring

3.6.6.1 INTRUSION DETECTOR

3.6.6.2 SMOKE DETECTOR

3.6.6.3 OBSTRUCTION LIGHT SENSOR

3.6.6.4 AC POWER SENSOR

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3.6.6.5 TEMPERATURE SENSORS

3.6.7 RMS Security

3.6.7.1 SECURITY IMPLEMENTATION

3.6.7.2 SECURITY LEVEL DEFINITIONS

3.6.8 RMS Data and Control Filtering

3.6.9 RMS Failure Protection

3.6.10 Interface with RMM Subsystems

3.7 DATA SECURITY

3.7.1 Access Control

3.7.2 Audit Logging

3.8 DME SYSTEM DESIGN CHARACTERISTICS

3.8.1 Maintainability

3.8.1.1 REAL TIME CLOCK/CALENDAR

3.8.2 Reliability

3.8.3 Modular Construction

3.8.3.1 EQUIPMENT MOUNTING

3.8.4 Test Points

3.8.5 Interchangeability

3.8.6 Corrective Maintenance

3.8.7 Preventative Maintenance

3.8.8 Software/Firmware Updates

3.8.9 Electrical Interfaces to DME Antenna

3.8.10 RF Input/Output Connectors

3.8.11 Grounding and Bonding

3.8.12 Input Power

3.8.12.1 AC POWER

3.8.12.2 EQUIPMENT DIRECTLY CONNECTED TO LINE POWER

3.8.12.3 POWER PLUGS, CORDS, AND OUTLETS

3.8.12.4 LEAKAGE CURRENTS

3.8.12.5 POWER FACTOR

3.8.12.6 INRUSH CURRENT

3.8.12.7 HARMONIC DISTORTION

3.8.12.8 CIRCUIT OVERLOAD PROTECTION

3.8.12.9 INPUT POWER CONDITIONS

3.8.12.10 BACKUP DC POWER

3.8.12.11 TRANSFORMER ISOLATION OF NON-SWITCHING DC POWER SUPPLIES

3.8.13 Removable Parts and Mating Connectors

3.8.14 Electronic Equipment Assembly Requirements

3.8.14.1 COMPONENT MOUNTING

3.8.14.2 PRINTED CIRCUIT BOARDS

3.8.14.3 ASSEMBLY

3.8.14.4 WIRE WRAP

3.8.15 Shelf Life

3.8.16 Accessibility

3.8.16.1 GENERAL

3.8.16.2 ENCLOSURES

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3.8.16.3 MAINTENANCE ACCESS

3.8.17 Thermal Design

3.8.18 Materials Processes and Parts

3.8.18.1 DISSIMILAR METALS

3.8.18.2 METALS, CORROSION RESISTANCE

3.8.18.3 CORROSION-RESISTING FERROUS ALLOYS

3.8.18.4 FLAMMABLE MATERIALS

3.8.19 Equipment Manufacturing Processes

3.8.19.1 STRAIN RELIEF

3.8.19.2 PAINTED FINISH

3.8.20 Electrical Parts

3.8.20.1 BATTERIES

3.8.20.2 OVERCURRENT DEVICES

3.8.20.3 CONNECTORS WITH THERMOCOUPLE CONTACTS

3.8.20.4 ELECTRICAL POWER CONNECTORS

3.8.20.5 SWITCHES

3.8.20.6 WIRING

3.8.21 Toxic Products

3.8.22 Nameplates and Markings

3.8.22.1 NAMEPLATES

3.8.22.2 MARKINGS

3.8.23 Workmanship

3.8.23.1 CLEANING

3.8.23.2 THREADED PARTS OR DEVICES

3.8.23.3 SHIELDING

3.8.23.4 CONTAINMENT

3.8.23.5 INSULATION

3.8.23.6 CLEARANCE

3.8.24 Employee Safety

3.8.24.1 ELECTRICAL SAFETY

3.8.24.2 GROUND POTENTIAL

3.8.24.3 SHIELDING

3.8.24.4 GUARDING OF RF VOLTAGES

3.8.24.5 INTERLOCKS

3.8.24.6 HIGH VOLTAGE PROTECTION

3.8.24.7 HIGH CURRENT PROTECTION

3.8.24.8 ELECTRICAL CONNECTORS

3.8.24.9 MECHANICAL HAZARDS

3.8.24.10 MECHANICAL INTERCONNECTION

3.8.24.11 GLASS FIBERS

3.8.24.12 SAFETY MARKINGS, SIGNS, TAGS, AND SYMBOLS

3.8.24.13 DISPLAY WARNINGS

3.8.24.14 BATTERY SAFETY

3.8.24.15 FIRE LIFE SAFETY

3.8.24.16 SEISMIC ANCHORING

3.8.24.17 PERSONAL PROTECTIVE EQUIPMENT (PPE)

3.8.25 Mechanical Parts

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3.8.25.1 CONTROLS AND SWITCHES

3.8.25.2 FASTENER HARDWARE

3.8.25.3 VENTILATING FAN MOTORS

3.8.25.4 BEARINGS

3.8.26 Human Engineering

3.8.26.1 NOISE CRITERIA

3.8.26.2 IDENTIFICATION OF NOISE HAZARD AREAS AND EQUIPMENT

3.8.26.3 DISPLAY INFORMATION

3.8.26.4 VIRTUAL DISPLAYS - FLASH

3.9 INSTALLATION

4. VERIFICATION

4.1 METHODS OF VERIFICATION

4.1.1 Inspection (I)

4.1.2 Analysis (A)

4.1.3 Demonstration (D)

4.1.4 Test (T)

4.2 TEST ALLOCATION

4.2.1 Development Test (DT)

4.2.2 Operational Test (OT)

4.3 GENERAL PROCEDURES

4.3.1 Test Tools

4.3.1.1 ELECTRONIC TEST EQUIPMENT

4.3.1.2 TEST SIMULATORS

4.3.1.3 ANTENNA TEST RANGE

4.3.2 Pulse Characteristics

4.3.2.1 SPACING

4.3.2.2 RISE TIME

4.3.2.3 DECAY TIME

4.3.2.4 PULSE TOP

4.3.2.5 PULSE WIDTH

4.3.3 Electrical Grounding

4.4 SPECIFIC PROCEDURES

4.4.1 Environmental Conditions

4.4.1.1 NON-OPERATING CONDITIONS

4.4.1.2 OPERATING CONDITIONS

4.4.2 Electromagnetic Compatibility (EMC)

4.4.3 Receiver Recovery Time

4.4.4 Receiver Sensitivity

4.4.4.1 VARIATION WITH INTERROGATION LOADING

4.4.4.2 ADJACENT CHANNEL INTERROGATIONS

4.4.5 Reserved

4.4.6 Tuning and Spurious Output

4.4.7 Pulse Shape

4.4.8 Pulse Coding

4.4.9 RF Pulse Spectrum

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4.4.10 Out-of-Band Spurious Radiation

4.4.11 Antenna Procedures

4.4.11.1 POLARIZATION

4.4.11.2 VSWR

4.4.11.3 GAIN

4.4.11.4 VERTICAL FIELD PATTERN

4.4.11.5 HORIZONTAL FIELD PATTERN

4.4.12 Power Quality Requirements

4.4.12.1 POWER FACTOR

4.4.12.2 INRUSH CURRENTS

4.5 VERIFICATION REQUIREMENTS TRACEABILITY MATRIX

5. PACKAGING

6. NOTES

6.1 DEFINITIONS

6.1.1 Automatic Gain Reduction (AGR)

6.1.2 Continuous Wave (CW)

6.1.3 Control

6.1.4 Echo Suppression

6.1.5 Electromagnetic Interference (EMI)

6.1.6 Equivalent Isotropically Radiated Power (EIRP)

6.1.7 Executive Monitoring

6.1.8 Interrogation Signal

6.1.8.1 RADIO FREQUENCY PULSE SPECTRUM

6.1.8.2 RF PULSE SHAPE

6.1.8.3 PULSE CODING

6.1.8.4 INTERROGATION RATE

6.1.9 Line Replaceable Unit (LRU)

6.1.10 Mean Time Between Failures (MTBF)

6.1.11 Monitor Delay Time

6.1.12 Positive Attachment

6.1.13 Receiver Dead Time

6.1.14 Receiver Sensitivity

6.1.15 Receiver Threshold Triggering Level

6.1.16 Remote Monitoring and Logging System

6.1.17 Remote Maintenance Monitoring

6.1.18 Reply Efficiency

6.1.19 Special Tools

6.1.20 Squitter

6.1.21 Transponder Reply Delay Time

6.1.22 Transistor-Transistor Logic (TTL)

6.2 ACRONYMS, ABBREVIATIONS, AND INITIALIZATIONS

6.3 INTERNATIONAL CIVIL AVIATION ORGANIZATION (ICAO)

REQUIREMENTS TRACEABILITY

APPENDIX A - DME FREQUENCY CHANNELIZATION

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LIST OF FIGURES

FIGURE 3-1. DME Transponder Block Diagram FIGURE 3-2. Application of Limits to a Vertical Field Pattern for a DME Antenna FIGURE 3-3. Inrush Current Limit Ratios FIGURE 3-4. Nameplates FIGURE 3-5. Personnel Safety Sign Layout FIGURE 4-1. Power Quality Tests and Measurements Flow FIGURE 4-2. Inrush Current Limit Measurements

LIST OF TABLES

Table 4-1 Applicable Requirements From MIL-STD-461G Table 6-1 ICAO Annex 10 Compliance Matrix

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1. INTRODUCTION

1.1 Scope

This specification establishes the performance, design, test, manufacture, and acceptance requirements for solid-state ground station distance measuring equipment (DME) suitable for use in the National Airspace System (NAS) in conjunction with en route and terminal navigation aids.

This type of DME is known as DME/N where the “N” stands for narrow spectrum characteristics.

1.2 Overview

The DME System described herein is a radio frequency (RF) transmitter-receiver combination navigation system used for the reception and transmission of information for the purpose of determining the aircraft slant range distance from a ground station. The DME transponder provides distance information and facility identification information to properly equipped users within a defined service volume.

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2. APPLICABLE DOCUMENTS

2.1 General

The documents listed in this section are specified in sections 3 and 4 of this specification. This section does not include documents cited in other sections of this specification, or recommended for additional information, or as examples. While every effort has been made to ensure the completeness of this list, document users are cautioned that they must meet all specified requirements of documents cited in sections 3 and 4 of this specification, whether or not they are listed in this section.

2.2 Government Documents

2.2.1 FAA Specifications, Standards and Handbooks

The following specifications, standards, and handbooks of the exact revision level shown below form a part of this document to the extent specified herein.

FAA-C-1217H, Chg. 2 Electrical Work, Premises Wiring (2023)

FAA-E-3039A Protocol Specification, Common Message Handling Protocol (CMHP) (2018)

FAA-G-2100J Electronic Equipment, General Requirements (2022)

FAA-STD-001B Color and Texture of Finishes for NAS Equipment (1976)

FAA-HF-STD-001B Human Factors Design Standard (2016)

FAA-STD-019G Lightning And Surge Protection, Grounding, Bonding And Shielding Requirements For Facilities And Electronic Equipment (2024)

FAA-STD-032 Design Standards for National Airspace System Facilities (1996)

FAA-STD-049 Standard, Fiber Optic Telecommunication, Systems and Equipment (1994)

FAA Order 3900.19D FAA Occupational Safety and Health Policy (2024)

2.2.2 Other Government Documents, Drawings and Publications

The following other Government documents, drawings, and publications of the exact revision level shown below form a part of this document to the extent specified herein.

MIL-HDBK-454C General Guidelines for Electronic Equipment (2021)

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MIL-STD-461G Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment (2015)

MIL-STD-810H Test Method Standard, Environmental Engineering Considerations and Laboratory Tests (2019)

MIL-STD-889C Standard Practice, Dissimilar Metals (2016)

NAS-IC-51015108-01, v0.92 FAA Interface Control Document, Remote Monitoring and Logging System (RMLS) To Remote Monitoring Subsystem (RMS) Using Common Message Handling Protocol (CMHP) (2014)

2.3 Non-Government publications

The following documents form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract.

American National Standards Institute

ANSI Z358.1 American National Standard for Emergency Eyewash and Shower Equipment

(Copies of this document are available online at www.ansi.org)

American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE)

ASHRAE Standard 52.2 Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size (2020)

(Copies of this document are available online at www.ashrae.org.)

American Society of Mechanical Engineers (ASME)

ASME Y14.44 Reference Designations for Electrical and Electronics Parts and Equipment (2008)

(Copies of this document are available online at www.asme.org)

Electronic Components Industry Association (ECIA)

EIA/ECA-310E Standard, Cabinets, Racks, Panels and Associated Equipment (2005)

(Copies of this document are available online at www.ecianow.org)

Health Physics Society (HPS)

N2.1-2011 Radiation Symbol (2011)

(Copies of this document are available online at www.hps.org.)

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Institute of Electrical and Electronics Engineers (IEEE)

IEEE C62.41.2-2002 IEEE Recommended Practice on Characterization of Surges in Low Voltage (1000 V and Less) AC Power Circuits (2002)

IEEE 519-2014 IEEE Recommended Practice and Requirements for Harmonic Control in Electric Power Systems (2014)

IEEE C95.1-2019 Standard for Safety Levels with Respect to Human Exposure to Electric, Magnetic, and Electromagnetic Fields, 0 Hz to 300 GHz (2019)

IEEE C95.2-2018 Standard for Radio-Frequency Energy and Current-Flow Symbols (2018)

IEEE 149-1979 Test Procedures for Antennas (1979)

IEEE 1100-2005 Recommended Practice for Powering and Grounding Electronic Equipment (2005)

(Copies of these documents are available online at www.ieee.org)

Institute for Printed Circuits (IPC)

IPC-CC-830C Qualification and Performance of Electrical Insulating Compound for Printed Wiring Assemblies (2018)

IPC J-STD-001H Requirements for Soldered Electrical and Electronic Assemblies (2020)

IPC-CM-770E Guidelines for Printed Board Component Mounting (2004)

IPC-SM-780 Component Packaging and Interconnecting with Emphasis on Surface Mounting (1988)

IPC-A-600K Acceptability of Printed Boards (2020)

IPC-A-610H Acceptability of Electronic Assemblies (2020)

(Copies of these documents are available online at www.ipc.org)

International Electrotechnical Commission (IEC)

IEC 61000-3-2 International Standard for Electromagnetic Compatibility (EMC) – Part 3-2: Limits for harmonic current emissions

(Copies of this document are available online at www.iec.ch)

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National Electrical Manufacturers Association (NEMA)

NEMA 250 Enclosures for Electrical Equipment (1000 Volts Maximum) (2020)

NEMA C18.1M, Part 1 American National Standard for Portable Primary Cells and Batteries with Aqueous Electrolyte – General and Specifications (2021)

NEMA C18.1M, Part 2 American National Standard for Portable Primary Cells and Batteries with Aqueous Electrolyte – Safety Standard (2019)

NEMA C18.2M, Part 1 American National Standard for Portable Rechargeable Cell and Batteries – General Specifications (2019)

NEMA C18.2M, Part 2 American National Standard for Portable Rechargeable Cell and Batteries – Safety Standard (2021)

NEMA C18.3M, Part 1 American National Standard for Portable Lithium Primary Cell and Batteries – General Specifications (2019)

NEMA C18.3M, Part 2 American National Standard for Portable Lithium Primary Cell and Batteries – Safety Standard (2021)

NEMA WD 6 Wiring Devices – Dimensional Specifications (2016)

NEMA Z535.1 American National Standard for Safety Colors (2017)

NEMA Z535.2 American National Standard for Environmental and Facility Safety Signs (2017)

(Copies of these documents are available online at www.nema.org)

National Fire Protection Association (NFPA)

NFPA 70 National Electric Code 2020 Edition (2019)

(Copies of this document are available online at www.nfpa.org.)

Underwriters Laboratories Inc. (UL)

UL 268 Standard for Smoke Detectors for Fire Alarm Systems (2016)

UL 489 Molded-Case Circuit Breakers, Molded-Case Switches, and Circuit-Breaker Enclosures, Edition 13 (2016)

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UL 900 Standard for Safety Air Filter Units, Edition 8 (2015)

(Copies of these documents are available online at www.ul.com)

2.4 Order of Precedence

In the event of a conflict between the text of this document and the references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained.

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3. REQUIREMENTS

3.1 General Requirements

3.1.1 System Characteristics

The DME transponder shall:

FIGURE 3-1. DME Transponder Block Diagram

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3.1.2 Interlock Signal from the Instrument Landing System (ILS)

3.1.3 Integrity of Signal

3.1.4 Assigned Channel Assurance

3.1.5 Environmental Operating Conditions

Unless otherwise stated, all requirements of this specification shall be met over the full range of service conditions, derived from MIL-STD-810, described below.

3.1.5.1 Non-Operating Conditions

3.1.5.1.1 Non-Operating Temperature Range

The DME System packaged for storage, shipping, or transporting (non-operating) shall withstand a temperature range of -46°C to +71°C.

3.1.5.1.2 Non-Operating Altitude

The DME System packaged for storage, shipping, or transporting (non-operating) shall withstand atmospheric pressure of 575 to 1025 mbar (equivalent to approximately 15 000 ft above sea level in a standard atmosphere down to approximately 300 ft below sea level).

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3.1.5.1.3 Vibration

The DME System shall not be damaged when subjected to the vibrations listed in Table 514.8C-I, Method 514.8 Annex C of MIL-STD-810, and the exposure durations provided in Annex C paragraph 2.1.4.

3.1.5.1.4 Shock

The DME System shall not be damaged when subjected to the mechanically induced shock as specified in Method 516.8, Procedure II of MIL-STD-810.

3.1.5.2 Operating Conditions

3.1.5.2.1 Outdoor Temperature

All outdoor equipment shall operate in the temperature range of -46°C to +50°C.

3.1.5.2.2 Indoor Temperature

All indoor equipment shall operate in the temperature range of -10°C to +50°C.

3.1.5.2.3 Rain

All outdoor equipment shall operate while exposed to wind-blown rain, at a rate of 1.7 mm/minute (4 inches/hour), and up to 18 m/s (40 mph) blowing wind.

3.1.5.2.4 Operating Altitude

All indoor and outdoor equipment shall operate over the atmospheric pressure range of 700 to 1025 mbar (equivalent to approximately 10 000 ft above sea level in a standard atmosphere down to approximately 300 ft below sea level).

3.1.5.2.5 Wind Velocity

The DME antenna shall withstand blowing wind conditions up to 100 mph.

3.1.5.2.6 Ice Loading

The DME antenna shall withstand up to 0.5 inches accumulation of clear ice on all outdoor components.

3.1.5.2.7 Humidity

3.1.5.2.8 Fine Sand (Dust)

The DME antenna outdoor equipment shall be impervious to sand and dust intrusion, as described in 4.4.1.2.7.

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3.1.5.3 Lightning Protection

The electronic equipment shall be provided with devices that protect against atmospheric electricity and transients from nearby lightning strikes in accordance with FAA-STD-019.

3.1.6 Electromagnetic Interference (EMI) / Electromagnetic Compatibility (EMC)

3.2 Transponder

3.2.1 Operating Channels

3.2.1.1 Broadband Operation

Each RF component or device shall be designed to allow DME operation on any selected channel (see Appendix A for current channelization).

3.2.1.2 RF Tuning

3.2.1.3 Channel Frequency and Stability

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3.2.2 Duplexer

3.2.3 Receiver and Associated Circuitry

All receiver performance requirements in 3.2.3 and associated subparagraphs that pertain to interrogation signals shall be met when the following conditions apply:

3.2.3.1 Receiver Bandwidth and Stability

The minimum permissible bandwidth of the receiver shall be such that the transponder sensitivity level will not change by more than +3 dB (e.g., from -94 dBm to -91 dBm) when the total receiver drift is added to an incoming interrogation frequency drift of ±100 kHz in the opposite direction.

3.2.3.1.1 Receiver Bandwidth

The receiver bandwidth shall be sufficient to allow compliance with the accuracy requirement (3.2.5.6) when the input signals are those specified in 3.4.4.

3.2.3.2 Receiver Decoder

The transponder shall include a decoding circuit such that the decoder will decode and produce reply pulse pairs from interrogation signal pulse pairs occurring at spacings within 12 ±0.5 μs for X channels and 36 ±0.5 μs for Y channels.

3.2.3.2.1 Decoding Circuit Performance

The decoding circuit performance shall not be degraded by single pulses arriving before, between, or after the constituent pulses of a pair of the correct spacing.

3.2.3.2.2 Decoder Rejection Pulse Spacing

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3.2.3.2.3 Decoder Rejection Pulse Width

3.2.3.3 Receiver Dead Time

3.2.3.4 Receiver Recovery Time

3.2.3.5 Echo Suppression

3.2.3.5.1 Short Distance Echoes

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3.2.3.5.2 Long Distance Echoes

Note: In this context, echoes are undesired signals caused by electromagnetic scattering of the interrogator signal (e.g., multipath transmission, reflections).

3.2.3.5.3 Echo Suppression Disable

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3.2.3.5.4 Traffic Load Monitoring

Outputs shall be provided for local and remote monitoring of the total number of decoded pulse pairs per second (ppps) and the number of receiver desensitization periods triggered per second.

3.2.3.6 Receiver Sensitivity

3.2.3.6.1 On-Channel Sensitivity

3.2.3.6.1.1 Sensitivity Variation with Interrogation Loading

The transponder sensitivity level shall not vary by more than ±1 dB from the value measured in

3.2.3.6.1 for transponder loading between 0% and 90% of its maximum transmission rate, with the echo suppression circuits and AGR disabled.

3.2.3.6.1.2 Desensitization by Adjacent Channel Interrogation

3.2.3.6.1.3 Desensitization by Continuous Wave (CW)

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3.2.3.6.1.4 Desensitization by High Repetition Rate/High Duty Cycle Pulse Signals

In the presence of an input signal with a pulse width of 8 μs where the pulse rate is 30% of the transmitter duty cycle (37 000 pulses per second) and having a peak level equal to the CW level specified in 3.2.3.6.1.3-a (i.e., 10 dB below the on-channel threshold triggering level measured in the absence of interference), the maximum reduction in receiver sensitivity and reply efficiency shall not exceed 0.5 dB and 3%, respectively.

3.2.3.6.2 Sensitivity to Adjacent Channel Interrogations

Signals ±900 kHz or greater removed from the assigned channel nominal frequency and having signal levels up to -10 dBm shall not trigger the transponder.

3.2.3.6.3 Dynamic Range

3.2.3.6.4 Noise-Generated Pulse Pairs

When the receiver is interrogated at -94 dBm, with the AGR circuits disabled, and at a rate to produce a transmission rate equal to 90% of the maximum, the noise-generated pulse pairs shall not exceed 5% of the maximum transmission rate.

3.2.3.7 Interference Suppression

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3.2.3.8 Squitter

3.2.3.8.1 Random Squitter Pulse Pairs

3.2.3.8.2 Squitter Operation

Note: The minimum transmission rate should be as close as practicable to 700 ppps.

3.2.3.8.3 Squitter Decoding

3.2.3.8.4 Effect of Traffic Loading

3.2.3.8.5 Priority of Reply Pulses

3.2.3.9 Automatic Gain Reduction (AGR)

3.2.3.9.1 Gain Reduction Operation

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3.2.3.9.2 Interrogation Overload Signal

A signal shall be provided to the monitor to prevent receiver sensitivity alarms when sensitivity has been reduced by AGR operation.

3.2.3.10 Priority of Transmission

3.2.4 Identification Signals and Keying

3.2.4.1 Identification Signal

3.2.4.2 Identification Keying Source

3.2.4.3 Independent Identification Signal Characteristics

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3.2.4.4 Associated Identification Signal Characteristics

3.2.4.5 Identification Keying Control

The transponder shall provide controls to:

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3.2.5 Transmitter and Associated Circuitry

3.2.5.1 Transmission Rate

3.2.5.2 Tuning and Spurious Output

NOTE: The requirement above (b.) refers to the maximum signal at the output of the transmitter cabinet when the system is in any other mode but operational (i.e., on air).

3.2.5.3 Transponder Power Output

3.2.5.4 RF Output Power Control

The transmitter shall require no mechanical/hardware change to operate in the specified settings.

3.2.5.4.1 Initial Setting

Means shall be provided to permit setting the RF output power to within ±5% of the nominal preset levels in 3.2.5.3.

3.2.5.4.2 Test Setting

3.2.5.5 Reply Delay Values and Adjustments

Controls shall be provided to set the nominal reply delay time within 0.0625 μs of any desired value between the limits of 44 μs to 56 μs for X channels, or 50 μs to 62 μs for Y channels.

3.2.5.6 Accuracy

The transponder shall not contribute more than ±0.5 μs (75 m (250 ft)) to the overall system error.

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3.2.6 Transponder Output Signals

3.2.6.1 Pulse Shape

The modulated RF signal envelope of each pulse shall meet the following requirements when measured using a linear detector.

3.2.6.1.1 Rise Time

Pulse rise time shall be 2.5 +0.5/-1.0 μs.

3.2.6.1.2 Pulse Top

The instantaneous voltage amplitude within the pulse top shall not fall below the 95% value of maximum amplitude of the pulse.

3.2.6.1.3 Pulse Width

Pulse width shall be 3.5 ±0.5 μs.

3.2.6.1.4 Decay Time

Pulse decay time shall be 2.5 +0.5/-1.0 μs.

3.2.6.2 Pulse Coding

Pulses shall be coded in pairs with a spacing of 12 ±0.25 μs for X channels or 30 ±0.25 μs for Y channels.

3.2.6.3 Delay Time Variation

Reply delay time variation shall not exceed the following:

3.2.6.4 Pulse Power Variation

3.2.6.5 RF Pulse Signal Spectrum

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3.2.6.6 Out-of-Band Spurious Radiation

3.2.6.7 Inter-Pulse Output Level

3.2.6.8 Retriggering of Transponder

The transponder shall include a decoding circuit such that the transponder can be triggered only by pairs of received pulses having pulse spacings appropriate to interrogator signals as described in 3.4.4.4 and having pulse widths as described in 3.4.4.3.3.

Note: The specific requirements for rejecting invalid pulse spacing and pulse width are addressed in 3.2.3.2.2 and 3.2.3.2.3, respectively.

3.2.7 Stabilization of Performance Characteristics

After one minute of power being applied to the transponder, and within 6 s of being switched to operational mode:

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3.2.8 Duty Cycle Overload Protection

A means shall be provided to protect the transponder amplifier components from damage due to the effects of output duty cycles that exceed the ratings of those components.

3.2.9 Thermal Overload Protection

3.2.10 Performance Upon Fault Condition of RF Equipment Output Circuit

3.3 Antenna

3.3.1 Antenna Types

The DME transponder shall operate with any one of the following types of DME antennas:

3.3.2 Frequency Range

The antenna shall operate within the frequency band of 960 MHz to 1215 MHz without the need for tuning or adjustment.

3.3.3 Polarization

The predominant energy radiated by the antenna shall be vertically polarized.

3.3.4 Characteristic Impedance and VSWR

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3.3.5 Antenna Gain

3.3.6 Vertical Pattern

Note: These requirements are illustrated in Figure 3-2 along with a hypothetical standard omni-directional vertical radiation pattern.

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FIGURE 3-2. Application of Limits to a Vertical Field Pattern for a DME Antenna

3.3.7 Horizontal Pattern

3.3.7.1 Omni-Directional Type

The circularity shall not exceed ±1 dB.

3.3.7.2 Uni-Directional Type

3.3.7.3 Bi-Directional Type

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3.3.8 Radome and Weatherproofing

3.3.9 Antenna Mount

3.3.10 Monitor Probes

3.3.11 Antenna Cables

3.3.12 Obstruction Lights

All DME antenna types shall accommodate the mounting, power, and grounding of an obstruction light fixture on the top of the radome.

3.3.13 Power Handling

All DME antenna types shall be capable of handling DME signals with an instantaneous output power up to 2000 watts and an average power of 80 watts (4% duty cycle).

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3.3.14 Grounding

The antenna shall be provided with grounding termination lug(s) on the antenna mounting base flange, in accordance with the Bolted Connections paragraphs, and Bonding paragraphs of FAA-

STD-019.

3.4 Monitor

Note: In the event that more than one independent monitor is used, the requirements in this Section (3.4) apply to each independent monitor.

3.4.1 Operating Channels

3.4.1.1 Broadband Operation

One single design shall be utilized for each RF device to cover operation on any selected channel.

3.4.1.2 RF Tuning

Each RF device shall be capable of operating on any channel assignment without the need for retuning.

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3.4.1.3 Frequency Stability

Over the range of specified service conditions, the frequency of each output signal from the interrogation signal generator shall not vary more than ±0.001% from the assigned frequency.

3.4.2 RF Input Levels

All monitor performance requirements shall be met when the transponder has any initial RF peak output power level between 50 W and 1000 W.

3.4.3 Coupling Probe Inputs

3.4.3.1 DME Antenna

3.4.3.2 Transmission Line Directional Coupler

3.4.4 Interrogation Signal Generator

The interrogation signal generator shall provide interrogation and timing reference signals for the relevant functions of the transponder monitor.

3.4.4.1 Operational Modes

3.4.4.2 Pulse Synchronization Output

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3.4.4.3 RF Output Pulse Signal

The RF envelope of each pulse shall meet the following requirements when measured using a linear detector.

3.4.4.3.1 Rise Time

The rise time shall be 2.5 ±0.5 μs.

3.4.4.3.2 Pulse Top

The instantaneous voltage amplitude within the pulse top shall not fall below the 95% value of the maximum voltage amplitude.

3.4.4.3.3 Pulse Width

The pulse width shall be 3.5 ±0.5 μs.

3.4.4.3.4 Decay Time

The decay time shall be 2.5 +0.5/-1.0 μs.

3.4.4.4 Pulse Coding

3.4.4.5 Pulse Power Variation

The peak power of the constituent pulses of any pair of pulses shall not differ by more than 0.5 dB.

3.4.4.6 Detected RF Output Signal

A linear detected video waveform test point shall be provided via a female BNC connector on the front panel for determining the pulse characteristics and timing measurements.

3.4.4.7 RF Pulse Spectrum

3.4.4.8 Spurious Output

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3.4.4.9 Test RF Output Frequency

3.4.4.10 RF Output Level Calibration

3.4.4.11 RF Output Level and Accuracy

3.4.5 Transponder Monitor

3.4.5.1 Monitor Alarm Action

3.4.5.1.1 Primary Alarm

If any primary parameter (3.4.5.2.1), or if any parameter listed in 3.4.5.2.2 that is selected as primary, produces an out-of-tolerance condition, the monitor will cause the following actions to take place:

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3.4.5.1.2 Secondary Parameter Alert

If any of the monitored parameters set to secondary (3.4.5.2.2) produce an out-of-tolerance condition, the monitor shall cause a positive visual and aural indication of the alert condition (3.5.1.2).

3.4.5.1.3 Pre-Alarm

If any monitored parameter exceeds the pre-alarm limit, a maintenance alert shall be generated.

3.4.5.1.4 Maintenance Alert

3.4.5.1.5 Alarm Delay Time

3.4.5.1.6 Monitor Response Time

3.4.5.2 Monitored Parameters

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3.4.5.2.1 Primary Parameters

The following parameters shall be monitored as primary alarms:

3.4.5.2.2 Secondary Parameters

The following parameters shall be monitored and selectable as either primary parameter alarms or secondary parameter alerts:

3.4.5.2.3 Reply Delay

3.4.5.2.4 Transponder Pulse Spacing

3.4.5.2.5 Transponder Pulse Rate

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3.4.5.2.6 Reply Efficiency

3.4.5.2.7 Transponder Power Output

3.4.5.2.8 Radiated Power Level

3.4.5.2.9 Identification Keying

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3.4.5.2.10 Transmitter Frequency

3.4.5.2.11 Receiver Frequency

3.4.5.3 Test Signals and Monitoring Activities

The transponder shall not be triggered more than a total of 120 times per second for monitoring and/or automatic delay control purposes.

3.4.5.4 Transponder Tests

The following test results shall be available through the MDT and the Remote Monitoring and Logging System (RMLS) interface.

3.4.5.4.1 On-Channel Receiver Sensitivity

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3.4.5.4.2 Sensitivity at 200 kHz and 900 kHz

3.4.5.4.3 Triggering Level at Other Pulse Spacings

3.4.5.4.4 Echo Suppression

Means shall be provided to measure the echo suppression duration and threshold triggering level (3.2.3.5.2).

Note: Echo suppression measurements do not have associated alert or alarm limits.

3.4.5.4.5 Dead Time Gate

Means shall be provided to monitor the receiver dead time interval (3.2.3.3).

Note: Dead time interval measurements do not have associated alert or alarm limits.

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3.4.5.4.6 Voltage Standing Wave Ratio

Means shall be provided to measure the transmitter VSWR at the transmission line directional coupler.

3.4.5.4.7 Transponder Decoder Certification Tests

3.4.5.5 Monitor Alarm Limit Certification Tests

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3.4.5.6 Monitor Interrogator Data

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3.4.5.7 Monitor Failsafe

The monitor shall be failsafe such that failure of any part of the monitor subsystem, including any associated control action (transponder shutdown), either results directly in an alarm condition, or does not alter any alarm limit to allow an out-of-tolerance condition to occur without detection.

3.5 Control, Status and Indicator Functions

3.5.1 Front Panel

3.5.1.1 Controls

As a minimum, the following control functions shall be available from the front panel of the DME transponder:

3.5.1.2 Status and Indicators

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3.5.2 Maintenance Data Terminal (MDT) Software

3.5.3 Remote Control

Remote controls shall only be allowed when enabled from either the front panel or the MDT. See

3.6 for remote control function details.

3.5.4 Fault History

3.5.5 Fault Diagnostics

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3.5.6 Trend Analysis Data Collection and Storage

3.5.7 Automatic Reset Function

The DME transponder automatic reset function shall:

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3.6 Remote Maintenance Monitoring (RMM)

RMM consists of the various sensors, microprocessor(s), and software necessary to remotely monitor, control, record, and certify proper operation of the DME System to be furnished under this specification.

3.6.1 Remote Monitoring Subsystem (RMS)

3.6.1.1 RMS Functions

The DME RMS shall provide the following functions:

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3.6.2 Alarm and Alert Messages

3.6.2.1 Alarms

3.6.2.2 Maintenance Alerts

3.6.3 Non-Volatile Data Storage

3.6.4 RMS Data Sampling Rate

The RMS shall sample each parameter within the RMS and DME monitor no less frequently than once every second.

3.6.5 Spare Input/Output Capacity

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3.6.6 Environmental Monitoring

3.6.6.1 Intrusion Detector

3.6.6.2 Smoke Detector

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3.6.6.3 Obstruction Light Sensor

3.6.6.4 AC Power Sensor

3.6.6.5 Temperature Sensors

3.6.7 RMS Security

Log-on security shall be implemented to ensure that only authorized personnel can enter RMS commands.

3.6.7.1 Security Implementation

The RMS security design shall:

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3.6.7.2 Security Level Definitions

Security levels for the RMS are defined as follows:

3.6.8 RMS Data and Control Filtering

3.6.9 RMS Failure Protection

The DME System design shall employ a failsafe mechanism such that failures in the RMS function cannot cause a loss or degradation of navigation service to the user.

3.6.10 Interface with RMM Subsystems

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3.7 Data Security

3.7.1 Access Control

The DME System shall contain features in its design and operation that prevent unauthorized and disruptive access to the system by implementing the following requirements as a minimum:

3.7.2 Audit Logging

3.8 DME System Design Characteristics

3.8.1 Maintainability

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3.8.1.1 Real Time Clock/Calendar

3.8.2 Reliability

The DME System shall have a mean time between failures (MTBF) of not less than 8760 hours as a serial reliability model.

3.8.3 Modular Construction

3.8.3.1 Equipment Mounting

3.8.4 Test Points

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3.8.5 Interchangeability

3.8.6 Corrective Maintenance

The following time requirements assume the following: A single maintenance technician performs the repair; the technician has had adequate equipment-specific training; the repair work is performed under normal conditions in the equipment shelter; and a full set of spares and necessary tools are located at the shelter.

3.8.7 Preventative Maintenance

3.8.8 Software/Firmware Updates

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3.8.9 Electrical Interfaces to DME Antenna

3.8.10 RF Input/Output Connectors

3.8.11 Grounding and Bonding

3.8.12 Input Power

3.8.12.1 AC Power

3.8.12.2 Equipment Directly Connected To Line Power

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3.8.12.3 Power Plugs, Cords, and Outlets

The DME System shall include one 20 A, 125 VAC, NEMA WD 5 grounding duplex receptacle, installed and wired in accordance with the requirements of NFPA 70.

3.8.12.4 Leakage Currents

Leakage current shall be less than 5 mA.

3.8.12.5 Power Factor

The power factor (PF) for the DME equipment shall be within 0.7 (lag) – 0.7 (lead) if the power draw of the equipment is less than 2000 W.

3.8.12.6 Inrush Current

The ratio of peak inrush current to root mean square (rms) current for loads or devices up to 40 A, measured on the phase conductor with the highest current, shall be equal to or less than the ratio defined by Figure 3-3.

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FIGURE 3-3. Inrush Current Limit Ratios

3.8.12.7 Harmonic Distortion

The system shall meet the current harmonic distortion requirements stated in International Electrotechnical Commission (IEC) 61000-3-2:2018.

3.8.12.8 Circuit Overload Protection

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3.8.12.9 Input Power Conditions

The system shall operate within tolerance when the AC input power varies according to the following:

3.8.12.10 Backup DC Power

3.8.12.11 Transformer Isolation of Non-Switching DC Power Supplies

3.8.13 Removable Parts and Mating Connectors

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3.8.14 Electronic Equipment Assembly Requirements

3.8.14.1 Component Mounting

Component mounting shall be in accordance with IPC-CM-770 or IPC-SM-780, as applicable, except the term “not recommended” shall be interpreted as “reject.”

3.8.14.2 Printed Circuit Boards

Printed circuit boards shall be in accordance with IPC-A-600.

3.8.14.3 Assembly

Assembly shall be in accordance with IPC-A-610 and IPC J-STD-001.

3.8.14.4 Wire Wrap

Wire wrap shall not be used.

3.8.15 Shelf Life

Materials, packaging, and processes shall ensure the equipment will meet performance requirements after a period of two years in a non-operational state after FAA acceptance.

3.8.16 Accessibility

3.8.16.1 General

3.8.16.2 Enclosures

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3.8.16.3 Maintenance Access

3.8.17 Thermal Design

3.8.18 Materials Processes and Parts

3.8.18.1 Dissimilar Metals

3.8.18.2 Metals, Corrosion Resistance

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3.8.18.3 Corrosion-Resisting Ferrous Alloys

3.8.18.4 Flammable Materials

Materials used in the end item configuration shall be noncombustible, fire retardant, or self-extinguishing in the most hazardous conditions of the equipment environment.

3.8.19 Equipment Manufacturing Processes

3.8.19.1 Strain Relief

Each part lead terminating at a connection point shall allow for strain relief to minimize tensile or shear stress.

3.8.19.2 Painted Finish

3.8.20 Electrical Parts

3.8.20.1 Batteries

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3.8.20.2 Overcurrent Devices

3.8.20.2.1 Circuit Breakers

3.8.20.2.2 Fuses

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3.8.20.3 Connectors with Thermocouple Contacts

3.8.20.4 Electrical Power Connectors

3.8.20.4.1 Protective Measures for Unmated Connectors

3.8.20.5 Switches

Switches shall maintain their indicated state, i.e., open or closed, when subjected to any accidental force on the switch or the switch mounting equivalent to a 10g acceleration of either switch or mounting.

3.8.20.6 Wiring

The selection, application, and wiring practices for cable and wire shall be in accordance with the following subparagraphs.

3.8.20.6.1 Wiring – Electrical Clearance

Clearance between solder connections or bare conductors (such as terminal strips, stand-offs, or similar connections) shall not allow accidental contact between adjacent connections when subject to service conditions specified in this specification.

3.8.20.6.2 Wiring – Marking

All signal, control, and power wiring shall be uniquely identified to and within the enclosure along the wire and at each termination by either permanent insulation markings or by heat shrink labels.

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3.8.20.6.3 Wiring – Protection

3.8.20.6.4 Wiring – Bend Radius

The bend radius of wire and cable shall be greater than or equal to five times the cable diameter to avoid establishing a permanent set in the cable.

3.8.20.6.5 Wiring – Sleeving

3.8.20.6.6 Wiring – Panel Door Cables

Wiring to parts on a hinged door shall be contained in a minimum number of cables, arranged to flex without becoming damaged when the door is opened and closed.

3.8.20.6.7 Wiring – Through Hole Protection

3.8.20.6.8 Wiring – Arrangement

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3.8.20.6.9 Wiring – Slack

Discretely terminated wires and cables shall be as short as practicable and still allow for maintenance and operation without damage or crimping of the wires.

3.8.20.6.10 Wiring – Entrance Cabling

Wiring from cable entrances to terminal boards, plugs, jacks, and similar devices shall be harnessed and clamped or supported in a cable duct.

3.8.20.6.11 Wire

3.8.20.6.12 Wiring - Fungus Protection

Materials that support fungus growth shall not be used for wiring or wiring insulation.

3.8.20.6.13 Wiring - Aluminum Conductors

Aluminum conductors shall not be used for interconnections between LRUs.

3.8.20.6.14 Wiring - Termination of Signal and Control Wiring

Except for terminations using terminal strips, all external signal and control wiring shall be terminated with a connector.

3.8.20.6.15 Wiring - Fiber Optics

The use of fiber optics shall be in accordance with FAA-STD-049.

3.8.21 Toxic Products

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3.8.22 Nameplates and Markings

3.8.22.1 Nameplates

3.8.22.1.1 Equipment Titles

3.8.22.1.2 Serial Numbers

FA

A

-E -3

6/

/2

FI

G

U R

E

-4 . N am ep la te s

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3.8.22.2 Markings

3.8.22.2.1 Visibility of Parts Labels

All LRU parts that have labels or markings identifying data or ratings, shall be mounted so that the data is visible to maintenance personnel without the necessity for disassembly of parts or adjacent functional or structural parts.

3.8.22.2.2 Fuse Position Markings

All fuse positions shall be marked with the rated current capacity of the fuse to be employed therein and approved by the FAA.

3.8.22.2.3 Terminal Strips, Blocks, and Wafer Switches

All terminal strips, blocks, and wafer switches shall be identified.

3.8.22.2.4 Controls and Indicating Devices

3.8.23 Workmanship

The following workmanship requirements were derived from MIL-HDBK-454.

3.8.23.1 Cleaning

After fabrication, parts and assembled equipment shall be cleaned of smudges; loose, spattered, or excess solder; weld metal; metal chips and mold release agents; and any other foreign material that might detract from the intended operation, function, or appearance of the equipment.

3.8.23.2 Threaded Parts or Devices

Screws, nuts, and bolts shall show no evidence of cross threading, mutilation, or detrimental or hazardous burrs, and should be firmly secured.

3.8.23.3 Shielding

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3.8.23.4 Containment

3.8.23.5 Insulation

There shall be no evidence of burns, abrading, or pinch marks in the insulation that could cause short circuits or leakage.

3.8.23.6 Clearance

The clearance between wires or cables and heat-generating parts shall be sufficient to minimize deterioration of the wires or cables.

3.8.24 Employee Safety

3.8.24.1 Electrical Safety

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3.8.24.2 Ground Potential

3.8.24.3 Shielding

3.8.24.4 Guarding of RF Voltages

Transmitter output terminals, antennas, and other devices that carry sufficient RF voltage that may burn or injure personnel shall be protected from accidental contact.

3.8.24.5 Interlocks

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3.8.24.6 High Voltage Protection

3.8.24.7 High Current Protection

All power buses supplying 25 A or over shall be protected against accidental short circuiting by tools, jewelry, or removable conductive assemblies.

3.8.24.8 Electrical Connectors

3.8.24.9 Mechanical Hazards

3.8.24.10 Mechanical Interconnection

The design shall provide positive means to prevent the inadvertent reversing or mismatching of fittings, couplings, instrument leads, and electrical connections.

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3.8.24.11 Glass Fibers

3.8.24.12 Safety Markings, Signs, Tags, and Symbols

3.8.24.12.1 Markings

3.8.24.12.2 Accident Prevention Signs and Labels

3.8.24.12.3 Sign Design

Signs shall consist of three panels as shown on Figure 3-5.

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FIGURE 3-5. Personnel Safety Sign Layout

3.8.24.12.4 Sign Classifications and Detailed Design

3.8.24.12.4.1 Class I (Danger)

3.8.24.12.4.2 Class II (Caution)

3.8.24.12.4.3 Class III (General Safety)

3.8.24.12.4.4 Class IV (Fire and Emergency)

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3.8.24.12.4.5 Sign Placement

3.8.24.12.5 Symbols

The following symbols shall be used as applicable:

3.8.24.13 Display Warnings

3.8.24.14 Battery Safety

Battery systems may pose electrical safety hazards (electrical shock and arc flash) or chemical hazards if containing electrolytes/acid. An emergency eyewash/shower station shall be located immediately adjacent to strong caustics (e.g., batteries with electrolytes/acid, cleaners) and identified with a highly visible sign in accordance with ANSI Z358.1 and FAA Order 3900.19D.

3.8.24.15 Fire Life Safety

Equipment shall not block egress routes (3’ clearance), sprinklers, or fire extinguishers, and installation/removal activities shall not impact fire barriers/firestop systems (e.g., drilling through fire rated walls or floor penetrations) in accordance with FAA Order JO 6930.1B and OSHA 29 CFR 1910, Subpart E.

3.8.24.16 Seismic Anchoring

Equipment with the potential of falling shall meet the anchoring requirements for seismic activity in accordance with FAA-G-2100J and FEMA E-74.

3.8.24.17 Personal Protective Equipment (PPE)

PPE Hazard Assessments shall be conducted by a Safety and Health Specialist to determine whether hazards are present for selecting PPE (e.g., high voltage, hearing protection devices, eye protection) that will protect affected employee(s) from identified hazards and ensure employees are trained in the proper use, maintenance, and storage in accordance with FAA Order JO

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3900.79, ATO Personal Protective Equipment, and FAA Order 3900.19D, Chapter 9, Personal Protective Equipment and Respiratory Protection.

3.8.25 Mechanical Parts

3.8.25.1 Controls and Switches

3.8.25.1.1 Direction of Movement

3.8.25.1.2 Operating Controls

Controls necessary for the operation of the equipment shall be located on the front panel of the unit.

3.8.25.1.3 Adjustment Controls

3.8.25.1.4 Operation

3.8.25.1.5 Stops

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3.8.25.1.6 Locking Devices

3.8.25.1.7 Non-Turn Devices

All non-turning controls and bodies or cases of turning controls shall be equipped with a positive device to prevent their turning in the panel or in the assembly on which they are mounted.

3.8.25.2 Fastener Hardware

3.8.25.3 Ventilating Fan Motors

All ventilating fan motors (commonly called pancake type) shall:

3.8.25.4 Bearings

Any bearings used shall not require maintenance.

3.8.26 Human Engineering

3.8.26.1 Noise Criteria

Equipment located in general work areas (areas requiring occasional telephone use or occasional direct oral communications at distances up to 1.5 m (approximately 5 ft)) shall not exceed 65 dB(A).

3.8.26.2 Identification of Noise Hazard Areas and Equipment

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3.8.26.3 Display Information

3.8.26.4 Virtual Displays - Flash

3.9 Installation

The equipment shall be designed for installation, removal, and reinstallation without special tools unless approved by the FAA.

06/24/2025

4. VERIFICATION

4.1 Methods of Verification

4.1.1 Inspection (I)

Inspection is a verification method that is accomplished by a visual examination of the item, reviewing descriptive documentation, and comparing the appropriate characteristics with predetermined standards to determine conformance to requirements without laboratory equipment or procedures.

4.1.2 Analysis (A)

Analysis is a verification method that consists of comparing hardware or software design with known scientific and technical principles, technical data, models, or procedures and practices to verify that the proposed design will meet the specified functional/performance requirements.

4.1.3 Demonstration (D)

Demonstration is a verification method that is accomplished by operation, adjustment, or reconfiguration of items performing their designed functions under specific scenarios. The items may be instrumented and quantitative limits of performance monitored, but only observational data rather than actual performance data is required to be recorded for verification. Demonstration is often used to verify compliance with servicing, reliability, maintainability, transportability, and human factors engineering requirements.

4.1.4 Test (T)

Test is a verification method that is accomplished, with or without instrumentation, through systematic exercising of the application item under appropriate conditions with the collection, analysis, and evaluation of quantitative data.

4.2 Test Allocation

4.2.1 Development Test (DT)

The primary objective of DT is to demonstrate that all specified technical and performance requirements for a system or service have been met. DT is typically conducted within a controlled test environment and may include the use of third-party test facilities or laboratories. DT is conducted prior to FAA acceptance of the first article units.

4.2.2 Operational Test (OT)

OT encompasses the test and evaluation of a system’s or service’s operational requirements.