aviation cable factory

How to Route Aviation Cable Through Aircraft: A Professional Guide

Routing cables through an aircraft’s complex structure is a critical task demanding precision, adherence to safety standards, and a deep understanding of aircraft systems. Proper cable routing ensures reliable electrical and avionics function, prevents interference, and maintains the aircraft’s structural integrity and safety. Here’s a comprehensive, step-by-step guide to this essential process:

1. Planning & Preparation: The Foundational Step

• ​Review Documentation: ​Crucially, consult the aircraft’s specific Maintenance Manual (MM), Structural Repair Manual (SRM), Illustrated Parts Catalog (IPC), and relevant wiring diagrams (WDM – Wiring Diagram Manual / AWM – Aircraft Wiring Manual). These documents provide the approved routing paths, clamp types, separation requirements, bend radii, and fastener specifications.
• ​Assess Requirements: Determine the cable type, gauge, length, shielding requirements (if any), connectors, and the specific start and end points within the aircraft.
• ​Identify Paths: Identify existing cable runs, conduit paths, or designated stringer/raceway locations specified in the manuals. Note locations of sharp edges, hot components (engines, APU, heating ducts), hydraulic/pneumatic lines, moving parts (control cables, landing gear), and areas prone to fluid ingress or condensation.
• ​Risk Assessment: Consider potential damage during routing (abrasion, pinch points) and ensure the planned path meets minimum bend radius requirements for the cable type.
• ​Gather Tools & Materials: Collect necessary tools (fish tape, cable snakes, mechanics mirrors, bore scopes, protective conduit grommets, lubricant if approved for use by manuals, cable ties, tie-wrap guns, cable markers) and consumables (approved cable clamps, cushion clamps, grommets, heat-shrink tubing, sleeving like DR-25/Thermax).

2. Access Panel Removal: Gaining Entry

• ​Follow Procedures: Strictly follow the aircraft maintenance manual procedures for removing necessary access panels, interior linings, or floorboards. Document removed fasteners and organize them securely.
• ​Exercise Caution: Be mindful of adjacent systems, hydraulic lines, and existing wiring. Protect surfaces to prevent scratches or dents.
• ​Lighting & Visibility: Ensure excellent lighting within the work area. Use headlamps or work lights strategically.

3. Route Path Preparation (If Needed)

• ​Install Conduit/Grommets: If routing cables through bulkheads or sharp-edged structures, install protective conduit (e.g., nylon spiral wrap, split conduit) or grommets before feeding the cable. This prevents abrasion damage during and after installation.
• ​Clear Obstacles: Ensure the planned path is free of debris, loose fasteners, or old unused clamps that could damage the cable.

4. Cable Feed & Routing: The Core Process

• ​End Preparation: Temporarily secure or tape connectors to prevent damage. Apply protective caps if needed.
• ​Use Guides: Employ fish tapes or cable snakes meticulously:
  • Attach the cable securely to the leader (fish tape/snake end) using electrical tape or approved clips. Ensure a smooth, snag-free connection.
  • Carefully feed the fish tape/snake along the approved pathway, feeling for obstructions and maintaining the minimum bend radius. ​Never force it.
  • Use mechanics mirrors or bore scopes to navigate corners and inspect paths visually.
  • For long distances or complex paths, use pull strings strategically placed during initial routing or previous maintenance events.
• ​Gentle Feeding: While one technician guides the fish tape/snake from the exit point, another carefully feeds the cable at the entry point. Maintain gentle, steady pressure. Avoid kinking or putting the cable under excessive tension.
• ​Cable Protection: When passing cables through conduits or sleeves, ensure they slide easily without binding. Apply approved wire-pulling lubricant sparingly only if specified in manuals.
• ​Separation: Rigorously maintain specified separation distances from other wiring bundles (especially high-current/high-voltage lines), fluid lines, hot components, and control cables/mechanical linkages. Use standoffs, conduits, or physical barriers as per the design requirements.

5. Cable Securing & Clamping: Stability is Key

• ​Clamp Selection: Use only the clamps specified in the aircraft manuals for the cable size and location (e.g., cushioned P-clamps, Adel clamps, MS21919 series clamps).
• ​Attachment Points: Clamp cables securely to designated aircraft structure attachment points (lugs, brackets) designed for this purpose. ​Never clamp directly to fluid lines, tubing, or movable components.
• ​Spacing: Follow clamp spacing requirements outlined in the manuals (typically several inches apart). Secure bundles neatly without over-tightening clamps.
• ​Stress Relief: Ensure adequate slack near connectors and attachment points to prevent strain on terminals. Form drip loops where necessary to prevent fluid ingress into connectors.
• ​Tie-Wraps: Use tie-wraps sparingly and only for bundling cables within a primary clamp system or for very light dress-up purposes, adhering to approved techniques and tie-wrap types (typically MS-style or equivalent). ​Over-reliance on tie-wraps without underlying clamps is improper.
• ​Avoid Chafe Points: Ensure no wires or bundles rub against structure, other components, or each other. Use sleeving, spiral wrap, or protective tapes at potential chafe points.

6. Connection & Testing: Verification

• ​Connector Installation: Following proper procedures, connect the routed cable(s) to their designated terminal blocks, avionics components, sensors, or other endpoints. Ensure connectors are fully engaged and locked/secured.
• ​Continuity & Insulation Checks: ​Before applying power, perform rigorous continuity tests to ensure correct connection pin-to-pin and check for shorts to ground or between wires. Perform insulation resistance (megger) testing according to manuals to verify the integrity of the cable insulation. Correct any faults.
• ​Operational Testing: After confirming wiring integrity, perform any required operational tests of the system(s) affected by the newly routed cable(s).
• ​Final Inspection: Do a thorough visual inspection verifying the entire routing path, clamp installation, separation from hazards, absence of slack loops catching on structure/controls, and overall neatness.

7. Panel Installation & Documentation: Closure

• ​Reinstall Access Panels: Carefully reinstall all access panels, interior linings, and floorboards using the correct fasteners and torque values specified in the manual.
• ​Update Documentation: Record the work performed accurately in the aircraft maintenance records/logbooks, including details of the cable routed, path used, testing results, and referencing applicable maintenance manual chapters.

Critical Safety & Compliance Reminders

• ​Regulations & Standards: Cable routing MUST comply with FAA Advisory Circulars (AC 43.13-1B), EASA regulations, ICAO standards, and, most importantly, the ​specific aircraft manufacturer’s approved data and maintenance manual procedures. Deviations are unsafe and illegal.
• ​Certification: Cable routing work on aircraft should ​only be performed by certified technicians or under their direct supervision.
• ​Material: Use ​only aircraft-grade wiring, connectors, terminals, clamps, and insulating materials meeting relevant specifications (e.g., AS, MIL-SPEC, TSO-C).
• ​ESD Precautions: Take Electrostatic Discharge (ESD) precautions when handling sensitive avionics components and associated wiring.
• ​Workmanship: High-quality workmanship is non-negotiable. Neat, secure, compliant installations are vital for safety and reliability.

Routing aviation cable correctly is a demanding but essential skill in aircraft maintenance and modification. By meticulously following approved procedures, employing the right tools and materials, prioritizing safety at every step, and adhering strictly to airworthiness regulations, technicians ensure the reliable and safe operation of critical aircraft systems. This guide provides the core principles, but always defer to the specific aircraft’s official maintenance documentation.