ODV functions (HOPS)
- Hot Start Prevention shuts fuel flow at
- Over-speed protection (NP) from DEC at
- Purges main fuel manifold and allows back flow of high-pressure air for purging.
- Sends fuel through manifold to
HMU functions (PM CAN VDTO)
- Pumps fuel at high pressure
- Meters fuel to ODV in response to PAS,
LDS, trq. motor from DEC, & eng. variables.
- Collective Pitch Compensation through the LDS. When the collective is moved, Ng is reset for immediate Np response.
- Accel/Decel flow limiting preventing comp. stalls, eng. damage, or flame out.
- Ng limiting – Limits max torque available under low temp conditions.
- Variable Geometry Positioning of the inlet
guide vanes for optimum performance.
- DEC/EDECU lockout PAS Override& Control with ECU Inoperative. Allows pilot to mechanically bypass torque motor inputs.
- Torque Motor to Trim Ng Output. To fine tune engine output. Can be overridden in DEC lockout.
- Opens Vapor Vent for manual HMU priming, to remove air from HMU.