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1U1555 – GE Aviation OEM Thrust Reverser Actuator Assembly
Available now on the Airparts.aero Marketplace.
The GE Aviation 1U1555 is a high-load, flight-critical hydraulic linear actuator specifically engineered for the actuation of thrust reverser systems on high-bypass turbofan engines. As an OEM-certified component, this actuator provides the mechanical force required to deploy and retract the thrust reverser transcowl or blocker door assemblies. In the high-velocity environment of a landing rollout, the 1U1555 must overcome significant aerodynamic "buffeting" forces to lock the reverser into the deployed position, redirecting fan bypass air forward to provide essential aerodynamic braking.
Constructed from high-strength precipitation-hardened stainless steel (15-5 PH) and aerospace-grade aluminum alloys, the 1U1555 is built to withstand extreme thermal gradients and high-frequency vibrations. The assembly features an integrated mechanical locking mechanism (frequently a "lock-in-retract" or gimbal-lock design) that prevents uncommanded deployment during takeoff or cruise—a catastrophic failure mode. This actuator is a central element of the engine’s nacelle system, interfacing directly with the FADEC for precision timing and synchronization with other actuators in the ring.
Key Features
High-Pressure Hydraulic Architecture: Optimized for 3,000 PSI aircraft hydraulic systems, utilizing precision-honed bores to minimize internal bypass leakage and ensure rapid cycle times.
Failsafe Mechanical Locking: Features an internal secondary lock that physically prevents piston extension unless hydraulic pressure is applied to the "unlock" port, meeting stringent FAA/EASA safety mandates.
Redundant Sealing System: Employs high-durability glyd-rings and scraper seals compatible with Skydrol (LD-4/5), designed to prevent external leakage and exclude environmental contaminants during thousands of flight cycles.
Self-Aligning Gimbal Mounts: The 1U1555 utilizes spherical bearing mounts to accommodate airframe and nacelle flex, preventing "side-loading" that could lead to premature seal wear or rod scoring.
Integrated Feedback Transducer: Typically equipped with an internal LVDT (Linear Variable Differential Transformer) or proximity switch to provide the FADEC with sub-millimeter position data.
Technical Specifications
Part Number: 1U1555
Manufacturer: GE Aviation (Produced by Woodward or Collins Aerospace for GE)
Component Type: Hydraulic Linear Thrust Reverser Actuator (TRA)
Operating Pressure: 3,000 PSI (Standard System)
Operating Fluid: Skydrol LD-4, Skydrol 5, or equivalent Phosphate Ester hydraulic fluid
Material (Piston/Rod): 15-5 PH Stainless Steel (High-tensile, corrosion-resistant)
Material (Housing): 7075-T6 Aluminum with Hard-Anodize Finish
Stroke Length: Calibrated for specific GE engine nacelle geometry
Certification: FAA-PMA / EASA Form 1 (with OEM Traceability)
Aircraft Compatibility
Boeing 747-400 / 767-300: Equipped with General Electric CF6-80C2 engines.
Airbus A300 / A310: Equipped with GE CF6-series powerplants.
MD-11: (Center or Wing engine configurations).
Note: Thrust reverser actuators are position-specific (e.g., Upper, Middle, Lower). Consult the Aircraft Illustrated Parts Catalog (IPC) to verify the 1U1555 is correct for the specific clocking position on your engine.
Applications
The 1U1555 is utilized for Thrust Reverser Deployment. Its primary roles include:
Transcowl Translation: Moving the outer cowl aft to expose the cascade vanes.
Blocker Door Actuation: Simultaneously moving blocker doors to deflect bypass air.
Emergency Retraction: Utilizing system pressure to ensure the reverser stows and locks immediately upon pilot command or FADEC intervention.
Why Choose 1U1555?
Choosing a genuine GE Aviation 1U1555 is essential for maintaining Thrust Reverser Synchronization. In a multi-actuator system, the internal friction and damping characteristics must be identical; non-OEM actuators can cause "skewing" of the transcowl, leading to mechanical binding or structural damage to the nacelle track. Furthermore, the 1U1555 is built to handle the high-temperature "soak-back" that occurs after engine shutdown, a condition that causes inferior seals to harden and fail.
The 1U1555 operates as a differential-area hydraulic cylinder where the extension force is governed by $F = P \cdot A$. The engineering complexity lies in the dynamic load-path management during the transition from the "stowed" to the "deployed" state. As the transcowl moves, the center of pressure on the aerodynamic surfaces shifts, creating a non-linear resistive force. The 1U1555 is designed with an internal snubber (hydraulic cushion) at the end of the stroke to prevent structural "banging" or "peening" of the nacelle stops. The piston rod is typically precipitation-strengthened and chrome-plated to ensure a high hardness-to-ductility ratio, preventing mechanical seizing while providing a perfectly smooth surface for the high-pressure seals to maintain a hydrodynamic film during operation.
Note: This is a flight-critical, high-pressure hydraulic component. Prior to installation, the hydraulic system must be fully depressurized. Ensure the reverser transcowls are physically pinned or locked according to the AMM safety procedures to prevent accidental deployment during maintenance. Installation must be performed by a certified A&P mechanic in accordance with the Engine Maintenance Manual (EMM). Post-installation bleeding and synchronization checks are mandatory.
Documentation
No public-facing OEM internal blueprints are available for this proprietary part; refer to the Component Maintenance Manual (CMM) 78-31-XX.
