SAE AS 81044 Electrical Wire, Cross-linked Polyalkene Insulated.

The “SAE AS 81044 Electrical wire, cross-linked polyalkene insulated” standard, developed by the Society of Automotive Engineers (SAE), is an aerospace standard that defines performance and construction requirements for single-conductor electrical wires primarily used in military, aviation, and high-reliability applications. This standard covers wires typically in double-walled constructions containing a cross-linked polyvinylidene fluoride outer layer, often with cross-linked polyalkene (or similar radiation-crosslinked polymers) insulation.

This standard has replaced the older US military specification MIL-W-81044. Manufacturers now produce wires in full compliance with the SAE AS 81044 standard, including updated marking, labeling, and testing requirements.

The basic characteristics and structure of this standard are as follows:

• Insulation: Double-walled designs are common, with extruded, cross-linked polyalkene as the primary insulation and an outer sheath typically consisting of extruded, cross-linked polyvinylidene fluoride. Some variants utilize cross-linked alkane-imide polymer or polyarylene, alone or in combination.
• Conductive materials: Tin-plated copper, silver-plated copper, nickel-plated copper, or high-strength copper alloy. Multi-stranded conductors are standard for flexibility.
• Temperature range: -65 degrees to +150 degrees.
• Voltage rating: 600 Volts.
• Wall thickness options:
  • Lightweight (thin-walled): For maximum space and weight savings.
  • Normal/medium weight: For better mechanical protection.
• The advantages are as follows:
  • Excellent resistance to abrasion, cuts, chemicals, fuels, oils, and solvents.
  • Good cold flow resistance.
  • Low smoke production when burned.
  • Lightweight and compact: Ideal for high-density cable bundles in confined spaces.
  • Radiation cross-linked insulation provides superior thermal and mechanical stability compared to uncross-linked materials.

SAE AS 81044 cable is commonly used in the following areas:

• Military aircraft and vehicles
• Aerospace systems (aircraft fuselages, avionics systems, missiles)
• High-density cable bundles where space and weight are critical.
• Environments requiring high reliability, flame resistance, and low smoke.

The SAE AS 81044 standard is frequently referenced in standards such as SAE AS 50881 (Aerospacecraft wiring) and in FAA advisory guidelines for aircraft wiring.

The AS 81044 standard is preferred when low smoke, lightness, and high mechanical strength are prioritized.

For detailed requirements, engineers should refer to the latest revision of the SAE AS 81044 standard and the specific specifications page on the SAE website.

Cross-linked polyalkene insulation refers to electrical insulation made from polyalkene polymers (such as polyethylene or polypropylene) that have been chemically cross-linked to improve their performance.

Polyalkenes are a family of plastics derived from simple hydrocarbons (alkenes). Common examples include:

• Polyethylene (PE)
• Polypropylene (PP)

These materials are widely used in electrical insulation because they have good dielectric properties (they resist the flow of electric current).

Crosslinking is a chemical process that links polymer chains together to form a three-dimensional network instead of separate linear chains. Crosslinking significantly improves properties:

• Higher temperature resistance (does not melt easily)
• Better mechanical strength
• Improved chemical resistance
• Improved electrical performance
• Greater durability and resistance to aging.

The best-known cross-linked polyalkene insulation material is cross-linked polyethylene (XLPE). It is commonly used in the following areas:

• Power cables
• High-voltage transmission lines
• Building cabling

Cross-linked polyalkene insulation materials are used in the following areas:

• Medium and high voltage cables
• Automotive wiring
• Industrial power systems
• Underground and submarine cables

Compared to uncross-linked plastics, cross-linked polyalkene insulation material,

• It exhibits reliable performance under high electrical voltage.
• It retains its integrity at high temperatures.
• It has a longer lifespan.

The SAE AS 81044 standard is essential because it defines stringent requirements for insulation sheaths used in aerospace electrical systems where failure is unacceptable. The main reasons this standard is important are as follows:

• It ensures safety in extreme aviation and space conditions: Aircraft and spacecraft operate under the following conditions:
  • High and low temperatures
  • Vibration and mechanical stress
  • Exposure to fuel, oil, and chemicals.

This standard ensures that sheathing materials (typically including high-performance polymers such as cross-linked polyalkenes) provide insulation and protection under these demanding conditions, reducing risks such as short circuits or fire.

• Consistent material performance is guaranteed: Without a standard, different manufacturers could produce sheaths with varying properties in terms of wall thickness, dielectric strength, or heat resistance. This standard defines uniform performance criteria, ensuring that every approved product meets the same minimum quality level.
• It supports electrical system reliability: Aircraft cabling systems are dense and critical. The insulation sheath must provide the following:
  • It must prevent wear between the wires.
  • It must provide additional dielectric protection.
  • It must be resistant to wear and tear over long service periods.

This standard includes qualification and testing requirements to ensure long-term reliability.

• It describes rigorous testing methods: This standard specifies the following testing methods:
  • Thermal resistance
  • Flammability
  • mechanical strength
  • Fluid resistance

These tests simulate real aviation environments to ensure the casing will not fail in service.

• It ensures interchangeability and global supply: Aviation programs rely on multiple suppliers. This standard ensures the following:
  • Parts from different manufacturers are interchangeable.
  • The supply is simpler and more secure.
  • Maintenance and replacement are consistent worldwide.
• Aviation regulatory compliance: Regulators and manufacturers require certified materials. This standard ensures:
  • A recognized qualifications framework
  • Traceability and documentation
  • Trust for certifications and audits.

In conclusion, the SAE AS 81044 standard ensures that insulation sheaths used in aerospace applications are safe, durable, and reliable under extreme conditions, while also enabling consistent quality and global compliance.

For many years, our organization, with its competent and experienced staff, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting them in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services compliant with the SAE AS 81044 standard.