SAE AS603 Impact Testing of Hydraulic Hoses, Pipes and Fittings

Developed by the American Society of Automotive Engineers (SAE), the Aerospace Standard (AS) "SAE AS603: Impact Testing of Hydraulic Hoses, Tubing, and Fittings" describes the requirements and procedures for impact testing hoses, tubing, and fittings used in aviation hydraulic systems at 8000 psi nominal working pressure or less. This standard also specifies standard impact testing equipment to be used in performing the impact tests.

When observed on an oscilloscope, pulse traces appear as approximate pressure-time cycles. It is essential that these pressure-time curves be confined to the shaded area shown in the figure, and that the dynamic pulse trace produced by the tester matches the trace shown in the figure.

The SAE AS603 standard is a critical standard in the aviation industry and includes procedures for impact testing of hydraulic hoses, pipes and fittings used in aviation hydraulic systems.

The primary purpose of the impact testing described in this standard is to evaluate the durability and performance of these components under cyclic pressure conditions, simulating the stresses they encounter in real-world aerospace applications.

The main features of the SAE AS603 standard are as follows:

• Components included: Hydraulic hose, tubing and fittings.
• Pressure limits: Systems with nominal working pressures up to 8000 psi.
• Test procedures: Detailed methods for performing impact tests.
• Equipment specifications: Guide to standard test equipment to be used.

This standard ensures that components can withstand the repeated pressure cycles typical of aviation hydraulic systems, preventing failures that could jeopardize aircraft safety.

The SAE AS603 standard outlines several critical requirements for impact testing:

• Test conditions: Components are subjected to cyclic pressure pulses to simulate operational stresses. This standard specifies pressure levels, cycle frequency, and test duration.
• Test equipment: This standard refers to standardized impact testing equipment to ensure consistent and repeatable results across different testing facilities.
• Performance criteria: Components must demonstrate the ability to withstand a specified number of impact cycles without failure such as leakage, bursting, or material degradation.
• Documentation: Test results should be documented, including test conditions, equipment used, and any observed failures.
• Quality assurance: This standard emphasizes the importance of traceability and compliance with testing procedures to ensure reliability.

Hydraulic systems are an integral part of aerospace applications, powering critical functions such as landing gear, flight control surfaces, and braking systems. Failures in these systems can have catastrophic consequences, necessitating rigorous testing. The SAE AS603 standard plays a vital role in:

• Ensuring durability: Verifying that components can withstand the high-pressure cycles encountered during flight operations.
• Improving safety: Reducing the risk of hydraulic system failure that could jeopardize aircraft safety.
• Standardize testing: Facilitates interoperability and quality assurance by providing a consistent framework for manufacturers and test facilities worldwide.
• Supporting compliance: Ensuring components meet aerospace standards by aligning with regulatory requirements and industry best practices.

The SAE AS603 standard is part of a broader ecosystem of aviation standards. Related standards include:

• The “ISO 6772 Aerospace - Fluid systems - Impact testing of hydraulic hoses, pipes and fittings” standard is an international standard for impact testing, aligned with the SAE AS603 standard.
• The “SAE ARP603 Impact test equipment” standard was later replaced by the SAE AS603 standard.
• The standard “SAE J343 Test and test procedures for SAE 100R series hydraulic hose and hose assemblies” is a standard that complements the SAE AS603 standard for specific applications and contains test procedures for SAE 100R series hydraulic hose assemblies.

These standards provide comprehensive testing and quality control for hydraulic components in the aerospace and related industries.

Hydraulic hose, pipe and fitting components include:

• Hydraulic hose: Tubing and fittings are critical components in hydraulic systems, widely used to transmit fluid power in aerospace, automotive, industrial, and other applications. These components must withstand high pressures, extreme temperatures, and dynamic conditions, while also providing leak-free performance and durability.

Hydraulic hoses are flexible, reinforced tubes designed to transport hydraulic fluid under high pressure. They are typically made of synthetic rubber, thermoplastic, or PTFE and feature reinforcing layers (e.g., wire braid or spiral) to increase strength. These hoses compensate for movement, vibration, and alignment errors in systems by providing fluid transport between components. They are used in aerospace (e.g., landing gear, flight controls), construction equipment, and industrial machinery.

• Hydraulic tubing: Rigid or semi-rigid pipes, typically made of steel, stainless steel, or aluminum, used to transport hydraulic fluid in fixed installations. These pipes provide a stable, high-pressure conduit with minimal flexibility, ideal for long distances or precise routing. They are common in aircraft hydraulic systems, industrial presses, and automotive brake lines.
• Fittings: Connectors that join hoses, pipes, or other components in a hydraulic system. Common types include threaded, flared, crimp, or quick-connect fittings made from materials such as steel, brass, or stainless steel. Fittings provide secure, leak-proof connections between hoses, pipes, and system components such as pumps or actuators. They are used in all hydraulic systems to maintain system integrity under pressure and vibration.

Hydraulic hoses, pipes, and fittings form the backbone of fluid power systems, transmitting energy to perform mechanical work. Their primary roles include:

• Pressure resistance: Designed to handle high-pressure fluids, typically up to 8000 psi, in aerospace applications. The pressure rating must be equal to or greater than the system working pressure.
• Material compatibility: Materials must be resistant to corrosion and degradation caused by hydraulic fluids (e.g., petroleum-based, synthetic, or water-based fluids).
• Flexibility and rigidity: Hoses provide flexibility for dynamic systems, while pipes offer structural stability for fixed installations.
• Durability: Must be resistant to cyclic pressure surges, extreme temperatures, and environmental factors such as corrosion or abrasion.
• Environmental conditions: Must withstand temperature, vibration, and exposure to chemicals or UV light.
• Safety: Sealing performance is critical to preventing system failures, especially in aerospace applications where reliability is paramount.

To ensure reliability, these assemblies undergo rigorous testing in accordance with SAE AS603, a key standard for aerospace applications. Impact testing simulates cyclic pressure loads to verify durability. Components are subjected to repeated pressure surges to ensure they can withstand operational stresses without failure.

Consequently, the SAE AS603 standard is the cornerstone of quality assurance in aviation hydraulic systems, providing a rigorous framework for impact testing of hoses, pipes, and fittings. By standardizing test procedures and equipment, it enhances safety and reliability by ensuring components meet the stringent requirements of aviation applications. As aerospace technology continues to evolve, standards like SAE AS603 remain crucial for maintaining the integrity of critical systems.

Our organization, which has been serving for many years and meticulously following global developments in science and technology, employs a skilled team and extensive infrastructure to conduct testing, measurement, and analysis in a wide range of areas for businesses across all sectors. In this context, we also provide testing services in accordance with the SAE AS603 Hydraulic Hose, Pipe, and Fittings Impact Testing Standard.