Woodward 9902-399

Digital guide

Product Name: VSV / IGV Servovalve and Actuator System Component

Product Introduction: The 9902-399 is a member of Woodward’s VSV (Variable Stator Vane) and IGV (Inlet Guide Vane) electro-hydraulic control family, documented in Woodward manual 40136. Within the 9902 VSV/IGV product line, it operates as part of the dual servovalve and actuator system providing closed-loop hydraulic positioning of compressor variable geometry.

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Technical Specifications: Configuration-specific hydraulic flow rating, pressure class, and torque motor parameters for 9902-399 are defined in Woodward manual 40136. Each actuator provides up to 3.445 inches (87.50 mm) of output stroke. Fluid: MIL-L-23699 or MIL-L-7808.

Functional Features:

Dual torque-motor servovalve architecture (IGV + VSV channels)
Integral LVDT feedback per actuator
Optional accumulator interface via “ACC” port
System filtration protecting essential orifices

Application Scenarios: Gas turbine compressor variable stator vane and inlet guide vane control; anti-stall protection; part-load efficiency optimization.

Structural Characteristics: Aluminum servovalve housing with through-hardened stainless steel internal parts. Marked hydraulic ports (ROD, HEAD, ACC). Servovalve installs directly over the hydraulic pump via kit 8924-874.

Working Principle: Hydraulic pump pressure is metered by the torque-motor-driven pilot stage to the actuator. The actuator positions the VSV/IGV hardware. LVDT feedback closes the position loop in the electronic final driver.

Installation Requirements: Install servovalve over pump using kit 8924-874. Connect ROD/HEAD ports to the matching actuator ports. Connect ACC to external accumulator if required. Ensure filtration. Follow manual 40136 Chapter 2 for receiving, storage, and installation.

Usage Notes: Read manual 40136 entirely before installation, operation, or servicing. Turbine requires an independent overspeed shutdown device. Use proper PPE. Emergency shutdown readiness during start-up is mandatory. Observe ESD handling precautions.