Pneumatic 

Systems

We specialize in air turbine starter repair for jet and turboprop engines. Four Star restores reliable torque generation under extreme operating conditions. Each starter is fully disassembled, cleaned, and inspected for turbine blade erosion, gear and clutch wear, and seal integrity. Following reassembly, every unit undergoes test stand validation to confirm torque output, speed performance, and smooth clutch engagement at rated conditions.

Four Star provides system-level pneumatic maintenance and troubleshooting that goes beyond individual component repair. Our technicians identify root causes behind recurring issues. From contaminated bleed air and filtration problems to thermal or pressure regulation faults, our team helps operators improve reliability and reduce maintenance costs across the fleet.

Our experience across diverse aircraft types enables us to recognize patterns and provide insights that help operators improve pneumatic system reliability and reduce maintenance costs over the long term.

Pneumatic pressure regulator overhaul addresses the components that reduce high-pressure bleed air (typically 200–400 PSI) to precise, stable operating levels. Each regulator is inspected, resealed, and calibrated to maintain consistent output pressure under varying flow conditions, preventing system damage and ensuring long-term reliability.

We validate starters, valves, and regulators through leak, flow, and response testing that replicates in-service loads. This process confirms torque output, pressure stability, and sealing integrity across the full operating range. Our team validates that every unit meets or exceeds OEM performance specifications before return to service.

Our repair process includes thorough cleaning, erosion inspection, and contamination prevention during assembly to protect component integrity. When contamination damage is found, we identify the source and recommend filtration or maintenance adjustments that reduce wear and extend service life.

Each repair follows approved OEM or FAA repair procedures and includes complete documentation, from airworthiness certifications (FAA Form 8130-3 / EASA Form 1) to traceable parts records and test results, verifying performance to specification.

Our technicians analyze interactions between systems to identify root causes, like bleed air contamination, pressure regulation issues, environmental control, and engine performance problems. This cross-system approach helps operators prevent repeat failures, improve reliability, and maintain consistent performance across aircraft types, from regional turboprops to widebody transports.