The S-61 is known for its reliability, but even dependable aircraft need comprehensive care to stay in peak operating condition. Among the components that play a key role in flight control is the primary servo, one of the most demanding hydraulic parts on the airframe. Over time, exposure to extreme conditions and constant use puts stress on internal mechanisms. That’s where a structured overhaul process comes in.
Initial Inspection and Disassembly
The first stage begins the moment the component reaches Rotair’s facility. Each S-61 primary servo undergoes a receiving inspection to document external wear and shipping conditions. From there, it’s disassembled carefully, part by part. Technicians record key details throughout the teardown, tracking wear patterns, looking for corrosion, and identifying damaged or degraded components. This inspection provides a clear roadmap for the rest of the overhaul.
Every disassembled part is then separated for further evaluation. Fasteners, seals, pistons, and housings are all examined to decide whether they can be reused or reconditioned or need full replacement. This stage is vital for identifying hidden issues before they become major problems down the line.
Cleaning and Surface Preparation
Once stripped down, each component goes through a deep cleaning process to remove grease, fluid residue, and contaminants that build up over time. Ultrasonic cleaning tanks, media blasting, and chemical treatment are used depending on the material and geometry of the part. The goal here is to return every piece to a clean, inspectable state.
Surface prep continues with dimensional checks. Technicians verify part tolerances against OEM specifications using calibrated instruments. If wear is detected outside acceptable limits, the part is either re-machined or replaced. By the end of this step, the parts are cleaned, measured, and ready to be brought back into working condition.
Replacement and Reconditioning
Rotair maintains a large inventory of replacement parts, including seals, bearings, and other wear items specific to the S-61 servo. Using only approved materials, their team replaces all necessary items and reconditions reusable components through processes like grinding, honing, and polishing. These techniques help restore tight tolerances and fluid passage integrity.
Every repair and replacement decision is documented and reviewed, making the process transparent and traceable. At this stage, each part is as close to new as possible—and in some cases, made better with updated components or coatings that extend service life.
Reassembly by Skilled Technicians
Once parts are prepped and verified, the reassembly phase begins. Precision and consistency matter here. The internal servo components, like pistons, valves, and actuators, are installed using torque specifications and sequences based on OEM data and Rotair’s proprietary procedures.
Technicians take care to lubricate every contact surface correctly, align hydraulic pathways precisely, and verify that each moving part works smoothly before the servo is sealed. This step is just as focused on quality as it is on functionality.
Hydraulic Testing and Performance Validation
After reassembly, the overhauled S-61 primary servo enters the test cell. Here, it’s run through a series of hydraulic and functional tests that replicate real-world flight conditions. Fluid pressure, actuator response, and leakage tolerances are all measured and monitored.
Rotair uses advanced diagnostic tools to monitor the unit under load, checking for performance consistency and responsiveness. If anything is out of range, the servo is pulled back for adjustments before undergoing a retest. Nothing leaves the facility without meeting strict performance benchmarks.
Final Inspection and Documentation
Once testing is complete, the primary servo is sent for a final visual inspection. It’s painted, labeled, and prepared for shipment with full traceability documentation. This includes teardown notes, part numbers, testing results, and service certifications.
Rotair’s overhaul records satisfy compliance and offer valuable insights for maintenance planners. Operators gain a deeper understanding of component lifespan and patterns of wear over time.
Need expert support for your S-61 primary servos? At Rotair Aerospace Corporation, we provide tailored solutions, keeping your fleet reliable and mission-ready. Contact us today to learn more!