306-8 - Low Pressure Fuel/Oil Rubber Hose

Aeroquip 306-8 – Low-Pressure Fuel & Oil Rubber Hose (-8 Size, 1/2" ID)

Available now on the Airparts.aero Marketplace.

Overview

The Eaton Aeroquip 306-8 is a lightweight, low-pressure synthetic rubber hose designed specifically for fuel, oil, and instrument lines in general aviation aircraft. This is not a high-pressure hydraulic hose; it is an engineered solution for applications where light weight and flexibility are primary requirements. The -8 (Dash 8) size corresponds to a 1/2-inch inside diameter. The hose is constructed with a seamless, fuel- and oil-resistant synthetic rubber inner tube, reinforced with a single braid of cotton, and protected by a distinctive black lacquered and impregnated cotton braid outer cover.

The Aeroquip 306 series is the industry standard for fabricating flexible lines for applications such as instrument gauge lines and vent lines on a wide range of general aviation aircraft. It is designed to be used with Aeroquip's 491 series of detachable, reusable fittings, allowing for custom hose assemblies to be fabricated in the field. This product is typically sold by the foot.

Key Features

• Manufactured by Eaton Aeroquip: Produced by a global leader in aerospace fluid conveyance systems, ensuring the highest standards of quality and reliability.

• Lightweight Cotton Braid Construction: The cotton braid reinforcement and cover provide the required pressure resistance while being significantly lighter and more flexible than steel-braided hose.

• For Low-Pressure Fuel and Oil: The synthetic rubber inner tube is specifically compounded to resist degradation from long-term exposure to petroleum-based fuels and lubricating oils.

• Compatible with Reusable Fittings: Designed for use with the Aeroquip 491 series of reusable fittings, allowing for field fabrication and repair of hose assemblies.

• -8 Size (1/2" ID): The standard -8 size for a wide range of low-pressure fluid and vent line applications.

Technical Specifications

• Part Number: 306-8

• Component Type: Bulk Low-Pressure Fluid Hose

• OEM Manufacturer: Eaton (Aeroquip brand)

• Inner Tube Material: Seamless synthetic rubber compound (fuel/oil resistant).

• Reinforcement: One braid of cotton.

• Outer Cover: Black, lacquered, and impregnated cotton braid.

• Inside Diameter (ID): 1/2 inch (0.500 inches)

• Maximum Operating Pressure: 100 PSI

• Operating Temperature Range: -65°F to +160°F (-54°C to +71°C)

Aircraft Compatibility

Aeroquip 306-8 is a universal bulk hose product used to fabricate hose assemblies for a vast range of piston-engine aircraft, including models from:

• Textron Aviation (Cessna, Beechcraft)

• Piper

• Mooney

• And in the experimental aircraft community.

Note: This is bulk hose material. Its applicability is determined by the specific hose assembly being fabricated, as defined by the aircraft or engine maintenance manual.

Applications

• Fabrication of flexible lines for fuel and oil pressure instrument gauges.

• Manifold pressure instrument lines.

• Fuel and oil tank vent lines.

• Low-pressure primer lines.

• WARNING: Not for use in high-pressure hydraulic systems, high-temperature applications, or for fuel/oil lines requiring fire resistance (such as firewall forward pressure lines).

Why Choose Aeroquip 306-8?

Using the correct, specified hose for an application is a critical airworthiness requirement. The Aeroquip 306-8 is the engineered solution for low-pressure instrument and vent lines. Its lightweight, flexible construction is ideal for routing through the airframe, while its materials are certified for compatibility with aviation fuels and oils. Substituting a non-certified hose (such as an automotive product) would introduce a significant risk of material degradation, swelling, and eventual failure, which could lead to a dangerous fuel leak or a loss of critical engine instrumentation in flight.

The Aeroquip 306-8 hose is designed as an integral part of a field-fabrication system using reusable fittings, such as the Aeroquip 491 series. This system's engineering principle relies on a purely mechanical seal. The fitting consists of two components: an outer socket and an inner nipple. To assemble, the socket is threaded (with a reverse left-hand thread) over the outside of the 306 hose's cotton braid cover. Then, the nipple, which has a standard right-hand thread, is lubricated and threaded into the socket. As the nipple advances, its tapered profile forcefully compresses the hose's inner rubber tube against the inner wall of the socket. This intense radial compression creates a secure, leak-proof seal and a strong mechanical grip on the hose reinforcement, all without the need for specialized, power-driven crimping equipment. This allows A&P mechanics to fabricate new, airworthy hose assemblies in the field with only standard hand tools and proper procedures.

Note: This is bulk hose material used to fabricate flight-critical hose assemblies. This product has a finite shelf life determined by its quarter/year of manufacture (cure date), which is printed on the hose layline. Expired hose must not be used. Hose assemblies must be fabricated and installed by a certified A&P mechanic using the specified reusable fittings (e.g., Aeroquip 491 series) and assembly procedures. The use of simple worm-gear clamps is generally not permissible for pressure-carrying instrument lines.

Documentation

Detailed technical specifications, fluid compatibility charts, and hose assembly fabrication instructions are available in the official Eaton Aeroquip aircraft hose catalog.

• Eaton Aeroquip Aerospace Hose and Fittings Catalog (e.g., AEB-A-AERO001): Provides all engineering and application data for the 306-series hose and 491-series fittings.