An aircraft headset cable is a specialized multi-conductor wiring assembly engineered to transmit microphone input, audio receive signals, and optional panel power between an aviation headset and the aircraft audio system. Built with dedicated shielding to prevent RF interference, these cables interface via dual GA, LEMO, or U-174 connectors.
Required Tools and Materials
- Replacement headset downcord assembly or factory control module, such as OEM-spec downcords from American Aviation Parts
- Precision electronics screwdriver set (standard #00 Phillips and micro Torx bits)
- Digital multimeter with fine-point needle probes
- Electrical contact cleaner suitable for high-impedance communication interfaces
- Clean, static-dissipative work mat
- Manufacturer-approved wiring schematic or pinout reference from the component maintenance manual
Step-by-Step Replacement Guide
- Identify the Connector Interface and Termination Standard
Verify whether the aircraft uses standard twin-plug General Aviation jacks (.250-inch PJ-055 headphone plug and .206-inch PJ-068 microphone plug), a military-style single U-174/U plug, or a 6-pin LEMO connector. When converting configurations, select purpose-built A20 Cable Assemblies rather than chaining passive Adapters, which can introduce signal degradation. If configuring for standard fixed-wing aircraft, select A20 Dual GA Plugs; for rotorcraft installations, select A20 Helicopter cable terminations.
- Isolate Cable and Jack Faults
Before disassembling the headset, isolate intermittent comms by testing the assembly against your aircraft Audio Panels. Rotate the headset plugs inside the panel jacks while monitoring for static to determine if wear exists on the aircraft-side jacks. Using a multimeter set to ohms, test continuity through the original cable while flexing the strain reliefs at both the plug boots and the earcup entry points. Resistance should remain below 1.0 ohm across every line; any spike indicates broken internal stranding within the shielded sheath.
- Disconnect the Defective Downcord Assembly
Ground your workstation to prevent electrostatic discharge into internal ANR (active noise reduction) circuit boards. Depending on the headset model, cable detachment occurs either via a quick-release terminal inside the battery control module or through terminal retention screws within the left earcup housing. Loosen the housing retaining hardware using the proper micro screwdriver bit. Carefully decouple the internal pin harness from the main board without applying lateral tension to the surface-mount connector. Verify your replacement assembly against available stock from American Aviation Parts before proceeding.
- Install and Seat the Replacement Cable Assembly
Align the terminal plug of the new cable with the keyed header on the headset PCB or control module. Press firmly until the connector clicks into positive engagement. If the cable incorporates an integrated strain relief grommet, verify that the grommet seats fully into the outer housing channel. Misalignment will pinch the insulation or compromise environmental sealing against sweat and cockpit humidity. Reinstall the earcup cover or battery module faceplate, torquing housing screws evenly until snug.
- Verify Pin Continuity and Panel Power Connections
For installations utilizing A20 Lemo Panel Power, confirm that panel-supplied bus voltage (typically 8 to 32 VDC) matches the headset power specification before plugging into the airframe. Measure continuity across the downcord pins to ensure no short circuits exist between microphone audio, mic ground, audio high, and shield ground. Proper isolation between shield ground and airframe common prevents alternator whine from entering modern digital Avionics.
- Perform Audio, Sidetone, and Push-to-Talk Functional Tests
Connect the headset to the cockpit communication system. Power the avionics master, activate the intercom, and verify clear incoming and outgoing audio. Adjust the squelch threshold to verify microphone gating. Test push-to-talk (PTT) operation to ensure microphone bias voltage does not cut out when the cord moves. If replacing older cords with specialized configurations, browse genuine replacement A20 Accessories at American Aviation Parts to maintain proper strain relief and audio fidelity.