Fluid distribution lines in aerospace systems—such as hydraulic lines, fuel linkages, and coolant conduits—must remain completely sealed against grueling structural demands. The SAE-AS33514 standard addresses this by regulating the specific physical geometry of the male and female adapter connection points.
SAE AS33514 wasn't originally an SAE document. It was taken directly from the U.S. Military Specification MS33514G
| Test | Procedure | Acceptance Criterion | |------|-----------|----------------------| | | 1.5x maximum operating pressure, hold for 5 minutes | No permanent deformation, no leakage | | Burst Pressure | 4x operating pressure (or as defined by tube material) | No rupture before reaching required pressure | | Impulse Fatigue | 100,000 cycles from 0 to maximum pressure at elevated temperature (135°C for phosphate-ester fluids) | No leakage or failure | | Vibration Endurance | Shaken at aircraft-specific frequencies (10–2000 Hz) with bending moment | No loosening or wear | | Fluid Compatibility | Immersion in Skydrol, MIL-PRF-83282, or MIL-PRF-5606 for 1,000 hours | No degradation of sealing surfaces | sae-as33514
: The current active version released in April 2019. Technical Design and Sealing Mechanism 1. Flareless Connection Design
| Section | What It Contains | |---------|------------------| | | Manufacturer name, MPN (manufacturer part number), date code, lot code | | Supply chain traceability | Purchase order, supplier name, distributor chain | | Inspection findings | Visual anomalies, X-ray, decapsulation, electrical test failures | | Risk assessment | Failure mode, application criticality (flight safety vs. non-safety) | | Disposition | Scrapped, returned, reworked, or used after risk analysis | It was taken directly from the U
The standard mandates (controlled root radius) per SAE-AS8879, which offer superior fatigue life compared to standard UNF threads. This is vital in high-vibration aircraft environments.
SAE International revises AS33514 roughly every 5–7 years. The latest revision (as of 2025) is , which clarified torque values for titanium tubes and added requirements for laser-etched traceability. Flareless Connection Design | Section | What It
| Revision | Publication Date | Status | | :--- | :--- | :--- | | AS33514 | August 1998 / Reaffirmed Jan 2007 | Historical / Reaffirmed | | AS33514A | May 23, 2007 | Historical / Revised | | AS33514B | March 17, 2008 | Historical / Revised | | AS33514C | April 17, 2015 | Historical / Reaffirmed | | AS33514D | January 2, 2019 | Historical / Revised | | AS33514E | April 11, 2019 | Current, Active |
SAE-AS33514 fitting ends are used in a wide variety of aircraft and defense systems, including:
: The standard mandates the use of highly controlled inch-profile UNJ screw threads featuring an increased minor diameter and a mandatory controlled root radius. This minimizes stress concentrations at the root of the thread, enhancing fatigue life under constant vibration.
The following standards are cited within SAE AS33514, meaning their requirements are integral to its application: