aviation cable factory

How to Read Aviation Cable Specifications: A Comprehensive Guide

In the high-stakes world of aviation, where safety and precision are paramount, understanding the components you use is non-negotiable. Aircraft cable assemblies – often termed wire ropes, control cables, or simply aviation cables – are fundamental structural and functional elements found in flight controls, landing gear, engine systems, and countless other applications. ​Knowing how to read and interpret aviation cable specifications is crucial for selecting the right cable, ensuring airworthiness, and maintaining operational safety.

Unlike generic hardware, aviation cables adhere to stringent international standards (like MIL-SPECs or SAE Aerospace Standards – often AS numbers) and manufacturer-specific codes. Misinterpreting even one detail can lead to catastrophic failure. Here’s a detailed breakdown of the key elements you’ll typically find in aviation cable specifications:

1. ​Construction (Number of Strands and Wires):
   • ​The Core Format: This is usually expressed as a number of strands x number of wires per strand. For example: ​**7x7** or ​**7x19**. A 7x7 cable has 7 strands laid around a core, with each strand itself made of 7 individual wires. A 7x19 cable has 7 strands, each containing 19 finer wires.
   • ​Significance: Construction determines flexibility and fatigue resistance. 7x7 is stiffer and stronger for its size, often used for stationary applications like tie-downs. 7x19 is much more flexible and better for applications involving pulleys or frequent bending, like flight control cables.
2. ​Material:
   • ​Type: Almost universally aerospace cables are made of ​Corrosion Resistant Steel (CRES), commonly referred to as ​Stainless Steel. The most frequent grades are ​302/304 (general corrosion resistance) and ​316 (superior corrosion resistance, especially against salt).
   • ​Coating (if applicable): Some cables feature coatings like ​Zinc (Galvanized) for certain military ground applications or ​Vinyl for added lubrication or corrosion protection in unique environments. This will be specified (e.g., Galvanized or Vinyl Coated).
3. ​Diameter:
   • ​Measurement: Clearly stated in ​inches or ​millimeters (e.g., 1/8 inch, 3mm, 4.76mm). Measurement is critical for compatibility with swage terminals, cable grips, pulleys, and guides.
   • ​Precision: Aviation diameters are tightly controlled. Ensure you’re matching the specification exactly.
4. ​Breaking Strength / Minimum Breaking Force (MBF):
   • ​The Critical Number: This is the ultimate tensile load the cable is certified to withstand before failure under laboratory conditions. Expressed in ​pounds (lbs) or ​kilonewtons (kN) (e.g., 1800 lbs, 8.0 kN).
   • ​Safety Factor: Actual operating loads must be significantly below the breaking strength, adhering to required safety factors dictated by FAA regulations or aircraft design requirements (often factors of 2 or more).
5. ​Length:
   • ​Measurement: Specified in ​feet (ft) or ​meters (m). For custom assemblies, this is the overall cut length before fitting terminals. Replacing an assembly requires matching this length precisely.
6. ​Standards Compliance (VERY Important):
   • ​Military Specifications (MIL-SPEC / MIL-DTL): Historically common (e.g., MIL-C-87134), though many are transitioning to SAE Aerospace Standards.
   • ​SAE Aerospace Standards (AS): The modern standard (e.g., AS85410, AS85426). These numbers refer to specific performance, testing, and material requirements the cable meets.
   • ​Manufacturer Part Numbers: Often align with the above standards but may have unique suffixes indicating material or coating (e.g., Flex-Z™ AS85410-316 indicates AS85410 construction with 316 Stainless Steel).
7. ​Finish:
   • ​Stainless Steel: Can be Bright (smooth finish) or Galvanized (zinc coated). Bright is most common in aerospace for corrosion resistance.
   • ​Treatment: Sometimes specified (e.g., pre-stretched).
8. ​Terminations / Fittings:
   • For cable assemblies, the specification will detail the fittings on each end (e.g., Swaged Stud Terminal, Double Lap Fork Terminal, Button Terminal, Sleeve).
   • Specifications include the specific part number for the terminal and the swaging standard used (e.g., NAS1000 for stud terminals, MS518xx for fork terminals). Correct fitting match to cable size and construction is vital.
9. ​Lay Direction:
   • ​Regular Lay: Strands are laid in the opposite direction to the wires within the strands. This is the standard and most common in aviation.
   • ​Lang Lay: Strands and their individual wires are laid in the same direction. Less common in primary aviation applications due to different wear characteristics.

Putting It All Together: Decoding an Example

Consider this specification line:
AS85410-001-03, 7×19 SS Cable, 1/8″ Dia, 1800 lbs MBF, 10ft Length, Nicopress® Sleeve Each End

• ​**AS85410-001-03:** It meets SAE Aerospace Standard AS85410. Suffix details the specific material and finish (often indicating Stainless Steel Type 302/304).
• ​**7x19 SS Cable:** Construction is 7 strands of 19 wires each, made of Stainless Steel.
• ​**1/8" Dia:** Diameter is 0.125 inches.
• ​**1800 lbs MBF:** Minimum Breaking Force is 1800 pounds.
• ​**10ft Length:** Uninstalled cable length is 10 feet.
• ​**Nicopress® Sleeve Each End:** Terminations are swaged aluminum compression sleeves (Nicopress® is a common brand) at both ends, meaning it’s an assembly ready to attach with appropriate fittings.

Why This Knowledge is Non-Negotiable

• ​Safety Compliance: Selecting a cable below the required MBF or incompatible with application movement (e.g., using a 7x7 where 7x19 is mandated) violates airworthiness regulations.
• ​Correct Replacement: Using a different construction or material unknowingly can compromise aircraft systems. Specifications ensure exact replacements.
• ​Preventing Premature Failure: Misinterpreting diameter can lead to incorrect swaging or binding in guides/pulleys, causing accelerated wear and potential failure.
• ​Regulatory Responsibility: Maintenance personnel and aircraft owners are responsible for using approved parts and materials per specifications.

Conclusion

Reading aviation cable specifications is not just about understanding a code; it’s about interpreting the blueprint for a critical safety component. By thoroughly understanding each element – construction, material, diameter, strength, length, standard compliance, and terminations – you ensure you select the right cable for the job every time. Always consult the aircraft’s specific maintenance manual (MM), illustrated parts catalog (IPC), or relevant Service Bulletin for the exact cable specification required. Never assume or substitute based solely on appearance or size. Your diligence in decoding these specifications is foundational to safe flight operations.