Hydraulic
Systems
Our hydraulic expertise covers flight control, landing gear, thrust reverser, engine, and brake systems. We specialize in the repair and overhaul of aircraft hydraulic pumps, valves, PCVs, PCUs, selectors, and servo actuators. Four Star delivers precise performance and reliability for every system we service.
High-Pressure System Expertise
Four Star Accessory Overhaul provides specialized aircraft hydraulic system maintenance for the high-pressure components that power flight controls, landing gear, brakes, and other critical systems. Our technicians service components operating at 3,000–5,000 PSI, maintaining tight tolerances and leak-free performance under demanding conditions.
Aircraft Hydraulic Component Repair
Aircraft hydraulic component repair and overhaul for pumps, actuators, and valves that generate, control, and transfer hydraulic power. Each component undergoes complete disassembly, precision cleaning, dimensional inspection, seal replacement, and functional testing under operating pressure to verify performance and efficiency.
Our team addresses common wear issues at seal interfaces, bearings, and valve spools to prevent leakage and premature failure, restoring components to like-new condition with full traceability and airworthiness documentation.
Aviation Hydraulic Actuators & Pump Overhaul
We provide actuator overhaul for landing gear, flight controls, thrust reversers, and cargo systems. That includes inspection, plating restoration, and load testing for proper extension and retraction speeds.
Four Star's hydraulic pump repair services cover piston, gear, and vane pumps, both engine-driven or electric, ensuring proper pressure generation, flow delivery, and relief valve function through calibrated test-stand verification.
Hydraulic Systems Experts
Our experienced technicians have extensive aviation industry knowledge. The Four Star team is equipped with the latest tools and technology to perform comprehensive repair and refurbishment of pneumatic components.
We can handle all your aircraft's pneumatic needs, from disassembly to cleaning, inspection, repair, and reassembly.
Hydraulic Landing Gear Accessory Service
Four Star supports landing gear hydraulics with repair and testing of uplocks, downlocks, sequence valves, and brake system components. Each is inspected for contamination, thermal wear, and structural integrity to ensure reliability in every cycle and safe operation on landing.
Strut Repair & Overhaul
Landing gear struts combine hydraulic and pneumatic systems to absorb landing loads and ensure smooth taxi performance. These complex components demand specialized tools, expertise, and testing to maintain safety and ride quality.
Our strut repair and overhaul capabilities include complete disassembly and inspection, cylinder honing or chrome restoration, seal and bearing replacement, and pressure and functional testing under simulated aircraft loads. We service oleo struts with precision, ensuring proper extension, compression, and gas charge for dependable performance.
Strut issues such as gas leakage, hydraulic fluid loss, or worn components can impact aircraft handling and height control. Our diagnostics identify root causes and implement repairs that restore reliability and compliance with OEM standards.
Our Comprehensive
Service Guarantee
Testing & Validation
Our advanced hydraulic test stands simulate real operating pressures, up to 5,000 PSI, to verify component performance under load. We measure flow, pressure, temperature, and response times with precision instruments traceable to national standards. Four Star ensures every repair meets or exceeds OEM specifications.
All hydraulic components undergo leak, efficiency, and functional testing before release to service, with full traceability and recorded test data included in permanent documentation.
FAA-Certified Hydraulic Repair Station
As an FAA-certified hydraulic repair station, Four Star operates under approved OEM and FAA repair procedures that guarantee compliance, safety, and consistency. Every repair includes airworthiness certification, test results, and parts traceability to satisfy all regulatory and logbook requirements.
Need Reliable Support for Your Hydraulic Systems?
From leak detection to complete actuator overhaul, our certified team is ready to help.
Contamination Control & Fluid Compatibility
Hydraulic systems are highly sensitive to contamination and fluid compatibility issues that can lead to premature component failure. At Four Star, every component is cleaned with filtered solvents, assembled in controlled environments, and flushed with filtered hydraulic fluid before final sealing to meet system-specific cleanliness standards.
Four Star verifies internal cleanliness through inspection and particle analysis of test fluids. We will confirm compliance with manufacturer and industry specifications. Our team also manages fluid compatibility across petroleum-based MIL-H-5606, synthetic Skydrol, and phosphate ester systems — segregating work by fluid type to prevent cross-contamination and ensure proper seal, solvent, and lubricant selection for each aircraft application.
Service Integration & System-Level Analysis
Our hydraulic system services integrate seamlessly with Four Star’s broader aircraft accessory capabilities, allowing coordinated maintenance and diagnostics that uncover root causes affecting multiple systems.
Hydraulic issues often stem from larger challenges such as contaminated fluid, thermal degradation, or electrical faults in motor-driven pumps. Our technicians analyze system interactions across hydraulic, pneumatic, electromechanical, and power generation systems to identify patterns, prevent repeat failures, and improve overall reliability.
With experience across systems operating from 1,500 to 5,000 PSI, we bring the technical depth and system-level insight needed to maintain performance and consistency across all aircraft platforms.
Common Questions
About Hydraulic Systems
Repair And Refurbishment
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