Custom Military Aerospace Cable Assemblies: Specifications We Build To
Neptec builds custom military aerospace cable assemblies to your drawing or ICD — MIL-DTL-38999, MIL-PRF-29504, VITA 66.x, AS6021. See the specifications we work to and our full component lineup.
Mil-aero programs rarely have a catalog part number waiting for them. The requirement arrives as a drawing, an interface control document, a legacy sample, or an early engineering concept: a specific connector on one end, a different one on the other, a length that has to route around structure, and an environmental spec that rules out most standard cable.
Neptec integrates customer-specified and approved-source components into finished cables and harnesses built to your specs. This post covers the specifications we build to.
How Military Aerospace Cable Assemblies Come Together
Every rugged assembly is a stack of four configurable decisions:
The interconnect | Connector family, contact or terminus system, and whether the assembly is optical, electrical, or mixed-media |
The transmission line | Fiber type and count, conductors, cable construction |
The protection | Jacket, tubing, conduit, or braid that keeps the run intact in its operating environment |
The configuration | Length, breakouts, mounting, and whether the assembly is fixed or deployable |
Changing one part often affects the others, so it makes sense to build the whole assembly in one place instead of sourcing and assembling parts downstream.
The interconnect: Rugged Connectors and Fiber Optic Termini
Neptec terminates and integrates rugged optical interconnects across several mil-aero connector families, including MIL-DTL-38999-family circular connectors, VITA 66.x optical interconnect modules, and Glenair Series 79 MT high-density, ruggedized MT-ferrule connectors. See the lineup at the end of the post for the components and manufacturers we regularly work with.
The specification work sits one level down, at the terminus:
Interconnect requirement | Typical specification or approach |
MIL-DTL-38999 Series III | MIL-PRF-29504/4 pin and /5 socket termini, commonly in size-16 cavities |
Aerospace rectangular | ARINC 801 termini in compatible connector systems |
Naval and shipboard | MIL-DTL-83526/TFOCA-type, GFOCA-type, or MIL-PRF-28876 connector systems, as specified |
High-density multifiber links | MT ferrule-based interfaces |
Hybrid optical/electrical interfaces | Fiber-optic termini and electrical contacts in a common connector shell |
Note: Program drawings, ICDs, and approved configurations define the fiber-optic cabling requirements, measurements, interchangeability, and interface control for each build.
SAE AS6021A defines items to consider when creating a fiber-optic cable-assembly specification or source-control drawing for aerospace installation. The customer drawing, ICD, and purchase-order requirements remain controlling.
Where those are still being defined, Neptec supports interconnect selection and manufacturability review.
The Transmission Line: Ruggedized Fiber Optic Cable Construction
Our range covers LSZH, fluoropolymer (PTFE / FEP / PFA), aerospace-grade fiber optic, and ruggedized ribbon, armored, and high-flex constructions.
The right cable construction depends on where it will be used and what the program requires. Application needs and invoked standards guide the final choice:
Requirement | Typical specification or test basis |
Aerospace fiber-optic cable | SAE AS5382, where applicable |
Military fiber-optic cabling system | MIL-STD-1678, applicable parts as invoked |
Low-smoke / halogen / smoke performance | IEC 60332, IEC 60754, and IEC 61034, as specified |
Spaceflight outgassing | ASTM E595; program-defined limits, commonly TML ≤1.0% and CVCM ≤0.10% |
Note: These references address different cables, fire, environmental, and material requirements. The controlling program documents define the applicable revision, test method, acceptance limits, and qualified cable construction.
Final selection is always tied to the applicable cable data sheet and program specification. See our guide to choosing the right fiber optic cable jacket for how material and fire rating drive that choice.
The Protection: Harness Tubing, Conduit, and Braided Sleeving
Tubing, metal conduit, and braided sleeving are applied alone or in combination, zone by zone, against the dominant threat — heat, abrasion, chemicals, crush, or EMI.
Protection requirement | Typical specification or approach |
Metallic braid for shielding or bonding | A-A-59569, where specified |
Routing, support, separation, and installation | SAE AS50881, where applicable |
Electrical-harness workmanship | IPC/WHMA-A-620, Class 3 when invoked |
Note: Braid coverage, shielding effectiveness, bonding method, clamp spacing, bend radius, and workmanship class are defined by the applicable drawing, cable/connector data, EMC requirements, and program quality plan.
The Configuration: Length, Breakouts, and Mounting
The physical definition of the finished assembly:
Length and tolerance — to your datum, typically connector face to connector face
Breakouts — branch locations and leg lengths
Mounting and strain relief — panel-mount or bulkhead, backshell orientation
Fixed or deployable — in-service flex cycles, bend radius, tensile loading, and reeling requirements
What Neptec Customizes Across All Four
The component list is the vocabulary. The build is what Neptec does with it. Every assembly is designed and manufactured to your requirement.
Custom harness and cable designs — single- and multi-fiber optical, single- and multi-conductor electrical, and mixed-media assemblies combining optical and electrical paths in one harness, within the selected cable, connector, insulation, and voltage/current ratings.
Flexible configuration — custom lengths, multi-branch breakouts, panel-mount and bulkhead terminations, and deployable assemblies for systems reeled out, repositioned, and recovered.
Mixed sourcing — different connector manufacturers or connector families may be used at opposite ends when permitted by the drawing, interface compatibility, approved-source requirements, and qualification evidence.
Quality Systems and Acceptance: ISO 9001:2015, AS9100D, and Optical Test
Neptec manufactures within an ISO 9001:2015 and AS9100D-certified quality management system. These certifications demonstrate controlled quality-management processes; they do not, by themselves, certify an assembly to a particular military, aerospace, or customer specification.
Program Documentation
For each program, the drawing, purchase order, and approved quality plan define, as applicable:
Configuration control
Source traceability
Inspection records
First-article documentation
Component conformity is managed against the applicable component specification and approved-source requirements.
Optical Acceptance and End-Face Inspection
Optical acceptance is verified against the program-defined test plan:
Acceptance requirement | Typical specification or approach |
Optical test methods | MIL-STD-1678 Part 2, where invoked |
End-face inspection | IEC 61300-3-35, where invoked |
Spaceflight fiber-optic workmanship | NASA-STD-8739.5A, when invoked |
Note: The assembly acceptance plan defines the required tests and limits, which may include continuity, fiber mapping, insertion loss, return loss, end-face inspection, and environmental or proof testing.
End-face contamination is a common and preventable cause of increased insertion loss, degraded return loss, and contamination transfer between mated interfaces. Our guide to fiber optic connector cleaning best practices covers the inspect–clean–reinspect workflow used in production.
Standards applicability: The specifications and standards referenced in this post are examples of requirements Neptec can support when they are invoked by the applicable program. The controlling drawing, ICD, purchase order, approved-source list, quality plan, and current revision of each specification establish the required configuration, materials, workmanship, test methods, acceptance criteria, and documentation. Not every standard listed applies to every cable assemblies.
Mil-Aero Cable Product Lineup & Manufacturers
The components we regularly integrate, with their manufacturers — each configurable within the applicable specification.
Next Step
Most programs know which parts they need. The difficulty is integration: the right terminus in the right connector on the right cable, protected correctly, measured against the standard your program invokes.
Send us a drawing, an ICD, or a part number you need matched. Our engineering team in Fremont, CA reviews the application before production begins.
