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2-8182-2 – GE Aviation Hydraulic Rate Safety Fuse
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The GE Aviation 2-8182-2 is a critical, high-precision hydraulic safety fuse designed to protect aircraft hydraulic systems from catastrophic fluid loss and pressure depletion in the event of a downstream line rupture or component failure. Functioning as an autonomous "circuit breaker" for fluid power, the 2-8182-2 is a flow-sensitive (velocity-fusing) device that monitors the volumetric flow rate passing through its internal orifice. Unlike a quantity-measuring fuse, this rate-sensitive fuse is engineered to remain open during normal high-demand operations but will snap shut instantaneously if the flow exceeds a predetermined, calibrated threshold.
The integration of the 2-8182-2 within a flight-control or landing gear actuation circuit provides a vital fail-safe layer. By isolating a failed branch of the hydraulic system, it preserves the integrity of the primary hydraulic reservoirs and manifolds, allowing the remaining flight-critical systems to continue operating on the residual pressure. This component is essential for maintaining the "fail-operational" or "fail-safe" requirements mandated for Part 25 transport-category aircraft.
Key Features
Velocity-Sensitive Actuation: Utilizes a precision-calibrated spring-and-poppet assembly that reacts to the pressure differential ($\Delta P$) created by excessive flow velocity.
Automatic or Manual Reset: Depending on the specific system configuration, the fuse is designed to remain closed until pressure is equalized or a maintenance reset is performed, preventing "chatter" during emergency conditions.
Hardened Steel Internal Components: Features precipitation-hardened stainless steel (typically 15-5 PH or 17-4 PH) internal valving to resist erosion and wire-drawing caused by high-velocity hydraulic fluid.
Zero-Leakage Seating: Engineered with an elastomeric or metal-to-metal primary seal that ensures positive shut-off once the fuse is tripped, preventing even minor fluid migration to the rupture site.
Compact Inline Envelope: Designed for direct integration into high-pressure hydraulic lines with minimal weight penalty and low parasitic pressure drop during normal operation.
Technical Specifications
Part Number: 2-8182-2
Manufacturer: GE Aviation (Formerly Unison/General Electric)
Component Type: Hydraulic Rate-of-Flow Safety Fuse
Operating Fluid: MIL-PRF-83282 or Skydrol LD-4 / 5 (Phosphate Ester) - Verify compatibility with specific seal O-ring dash number.
Nominal Operating Pressure: 3,000 PSI (Typical for commercial/military transport aircraft)
Proof Pressure: 4,500 PSI
Burst Pressure: 7,500 PSI minimum
Flow Rate Threshold: Calibrated to trip at specific GPM (Gallons Per Minute) over maximum system demand.
Body Material: High-strength Aluminum Alloy or CRES (Corrosion Resistant Steel)
End Fittings: Standard MS (Military Standard) or AS (Aerospace Standard) flared or flareless fittings.
Aircraft Compatibility
Boeing 737 Series: (Classic and NG variants)
Boeing 757/767: Hydraulic system distribution manifolds.
Lockheed C-130 Hercules: Utility and Flight Control booster systems.
General Electric Engine External Hydraulics: Used on various CF6 and GE90 powerplants for thrust reverser actuation lines.
Note: The aircraft Illustrated Parts Catalog (IPC) must be consulted to verify the specific dash-number application for your airframe serial number.
Applications
The 2-8182-2 is primarily installed in High-Risk Hydraulic Branches, such as lines leading to landing gear actuators, brake systems, or thrust reverser actuators. These areas are prone to damage from tire bursts, FOD (Foreign Object Debris), or mechanical fatigue. In these applications, the fuse prevents a single line break from "bleeding out" the entire hydraulic system.
Why Choose 2-8182-2?
Using an OEM GE Aviation safety fuse ensures that the spring tension and orifice diameter are calibrated to the exact millisecond response time required by the aircraft's certification basis. Non-certified or "will-fit" fuses may suffer from "nuisance tripping" during cold-weather operations (when fluid viscosity is high) or, conversely, fail to close during a genuine rupture, leading to total hydraulic failure and loss of aircraft control.
The 2-8182-2 functions through the application of Bernoulli’s Principle and the Continuity Equation. As hydraulic fluid passes through the internal restricted orifice, the velocity increases, causing a localized drop in static pressure. This creates a pressure differential ($\Delta P$) across the internal poppet. The fuse is balanced by a precision-calibrated spring that exerts a force ($F_s$) opposing the fluid's drag force. Under normal conditions, $F_s$ keeps the poppet in the open position. However, if a downstream rupture occurs, the flow velocity increases exponentially, causing the dynamic pressure to overcome the spring preload. This triggers the poppet to move into the seat, an action often referred to as "slugging." The design is sensitive to fluid viscosity; therefore, the internal geometry is optimized to account for the non-Newtonian behavior of phosphate-ester fluids across a wide temperature envelope, from -54°C to +135°C, ensuring reliability in all flight regimes.
Note: This is a flight-critical safety component. Installation must be performed by an A&P licensed mechanic in accordance with the applicable Aircraft Maintenance Manual (AMM). Ensure the system is fully depressurized before removal. Verify that the flow direction arrow on the fuse body matches the system architecture. This part may require specific bleeding procedures to remove entrapped air, which can cause premature tripping.
Documentation
MIL-H-5440 (General Requirements for Aircraft Hydraulic Systems)
No public-facing GE Aviation proprietary data sheet was located for this specific part; refer to the OEM Component Maintenance Manual (CMM).
