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SAE AS4273 Revision A, February 1, 2007
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(R) Fire Testing of Fluid Handling Components for Aircraft Engines and Aircraft Engine Installations
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AIA/NAS Aerospace Standards
This document establishes requirements, test procedures, and acceptance criteria for the fire testing of fluid handling components and materials used in aircraft fluid systems. It is applicable to fluid handling components other than those prescribed by AS1055 (e.g., hoses, tube assemblies, coils, and fittings).

It also is applicable to materials, wiring, and components such as reservoirs, valves, gearboxes, pumps, filter assemblies, accumulators, fluid-cooled electrical/electronic components, in-flight fluid system instrumentation, hydromechanical controls, actuators, heat exchangers, and manifolds. These components may be used in fuel, lubrication, hydraulic, or pneumatic systems.

Classifications

Component assemblies shall be classified according to fire test duration. The test methods described herein shall be applicable to each classification.

Fire Resistant

The capability of a material or component to perform those functions intended under the heat and other conditions likely to occur at the particular location during a fire and to withstand a 2000 °F flame (±150 °F) for 5 minutes minimum.

Fireproof

The capability of a material or component to withstand a 2000 °F flame (±150 °F) for 15 minutes minimum, while still performing those functions intended to be performed in case of fire.

Applicability Guidelines

All flammable fluid conveying components that are located in a designated fire zone shall be at least fire resistant. All flammable fluid tanks and their associated shutoff valves located in a fire zone shall be fireproof. Components which convey flammable fluids can be evaluated to a fire resistant standard provided the supply of flammable fluid is stopped by a shutoff feature. Engine fuel system components can be considered to have a shutoff feature if the fuel flow would be shutoff with engine shutdown. Engine oil system components must consider that oil flow may continue after engine shutdown because of windmilling causing continued rotation of the oil pump. It should be noted that historically most oil system components have been evaluated to a fireproof standard. Other flammable fluid conveying components such as hydraulic and thrust augmentation systems should be evaluated in a similar manner.

Components adjacent to fire zones may be required to be fire resistant or fire proof (see AC20-135 Appendix 1).

Components Protected by Nonintegral Shields

Components to be fire tested that are protected from direct flame impingement by a nonintegral fireproof device such as a shield, box, baffle, etc., must employ this device in the fire test. The device must be positioned per the installation and the instrumentation that measures the flame temperature during the test be within 0.25 inches (6.36 mm) from the device. The burner is positioned as defined in 4.7, and the component must be positioned in its actual relationship to the device.