6 29 fcom sa227 hydraulic

AIRCRAFT SYSTEMS HYDRAULIC HYDRAULIC SYSTEM SCHEMATIC

SA227‐ SERIES/FCOM/VTM

6.29.1

Figure 6.29‐1

Revision: Original Aug 1,2013

GO/FCOM/SA227‐SERIES/VTM

AIRCRAFT SYSTEMS HYDRAULIC SA227‐ SERIES/FCOM/VTM HYDRAULIC SYSTEM SCHEMATIC LEGEND

1. HYDRAULIC FLUID RESERVOIR 2. ENGINE PUMP SUCTION STANDPIPE 3. ENGINE DRIVEN HYDRAULIC PUMP 4. SYSTEM RETURN FILTER 5. ENGINE DRIVEN PUMP CHECK VALVE 6. FLAP POSITION SELECTOR VALVE 7. GEAR POSITION SELECTOR VALVE 8. GEAR BY PASS VALVE 9. GEAR UP TERMAL RELIEF VALVE 10. GEAR DOWN THERMAL RELIEF VALVE 11. SYSTEM RELIEF VALVE 12. FILTER RELIEF VALVE 13. FLAP UP THERMAL RELIEF VALVE 14. FLAP UP SUCTION CHECK VALVE 15. HAND PUMP SUCTION SUMP 16. RESERVOIR PRESSURIZATION RELIEF VALVE 17. FLUID FILLER & SCREEN 36. SIGHT GAUGES (I) 19. GEAR UP & NORMAL GEAR DOWN CYLINDER

20. GEAR UP & EMERGENCY GEAR DOWN CYLINDER 21. GEAR DOWN RESTRICTOR VALVE 22. EMERGENCY HAND PUMP (A) 23. SHUTTLE VALVE (I) 24. FLAP DOWN RESTRICTOR VALVE (A) 25. AUXILIARY GEAR SYSTEM SELECTOR VALVE (I) 26. AUXILIARY GEAR SYSTEM 27. PRESSURE GAUGE (I) 28. PRESSURE WARNING SWITCH (I) 29. EXTERNAL CONNECTION ASSEMBLY 30. SHUTOFF VALVE 31. FLAP LOCK VALVE 32. ACCUMULATOR 33. NOSE GEAR STEERING ACTUATOR 34. POWER BRAKE RETURN (OPTIONAL) 35. POWER BRAKE PRESSURE SUPPLY (OPTIONAL) 18. FLAP ACTUATING CYLINDERS 37. TRANSDUCER

NOTE COMPONENTS DESIGNATED (A) COMPRISE THE AUXILIARY SYSTEM. COMPONENTS DESIGNATED (I) COMPRISE THE INDICATING SYSTEM. ALL OTHER COMPONENTS COMPRISE THE NORMAL SYSTEM.

Revision: Original Aug 1,2013

GO/FCOM/SA227‐SERIES/VTM

6.29.2

AIRCRAFT SYSTEMS

HYDRAULIC SA227‐ SERIES/FCOM/VTM 6.29.3 HYDRAULIC SYSTEM

The aircraft hydraulic system is a closed center system that provides pressure for normal operation of the landing gear, wing flaps, nose wheel steering, and when installed, power and anti‐skid brakes. Major system components are a power pack, two engine driven pumps, two shutoff valves, an accumulator, associated lines, pressure transmitters, lights, and an emergency landing gear down hand pump. A pressure gauge in the instrument panel indicates main or emergency system pressure. System quantity is indicated by a sight gauge system located on the outboard side of the left nacelle.

The system is serviced with MIL‐H‐83282 (Brayco) fluid through pressure quick disconnects located forward of the left main gear doors. Gravity servicing can be accomplished through the power pack reservoir filler cap accessible from the outboard side of the left nacelle.

HYDRAULIC POWER PACK

The hydraulic power pack, located in the left hand nacelle, stores fluid and controls pressure provided by the engine driven pumps. Two selector valves in the bottom of the pack control operation of the gear and flaps. The upper cylindrical portion of the pack is used to store fluid for normal system use. The engine driven pumps are supplied from standpipes which reserve the last quart of fluid for emergency hand pump operation. A shutoff valve is installed in the supply line to each engine driven pump.

MAIN HYDRAULIC SYSTEM OPERATION

Either engine driven hydraulic pump is capable of delivering 5gpm (19 liters per minute) at 2,000 psi (13790 kPa). When gear or flap selection is made with cockpit controls, a solenoid actuated pilot valve on the power pack directs hydraulic fluid to the gear or flap actuators. Fluid from the return side of the actuators is routed through the opposite side of the selector valve and through a filter to thereservoir.

Limit switches actuated by the landing gear retraction mechanism open the circuit to the selector valve, permitting the spring loaded valve to return to the neutral position. The uplock mechanism mechanically locks the landing gear in the up position.

With landing gear extended, the selector valve stays in the gear down position and pressure is continuously exerted on the actuators until the engines are shut down and the battery switches are turned off. Normal gear extension or retraction time is five to seven seconds. With one pump inoperative the gear travel times remain about the same (within one second).

Hydraulic pressure is tapped off the nose landing gear down line to power the nose wheel steering actuator and the optional anti‐skid brake system.

ACCUMULATOR

An accumulator is installed near the left side of the hydraulic pack to dampen pressure fluctuations within the system.

Revision: Original Aug 1,2013

GO/FCOM/SA227‐SERIES/VTM

AIRCRAFT SYSTEMS HYDRAULIC MAIN HYDRULIC SYSTEM

SA227‐ SERIES/FCOM/VTM

6.29.4

Figure 6.29‐2

AUXILIARY HYDRAULIC SYSTEM

Figure 6.29‐3

Revision: Original Aug 1,2013

GO/FCOM/SA227‐SERIES/VTM

AIRCRAFT SYSTEMS

HYDRAULIC SA227‐ SERIES/FCOM/VTM 6.29.5 AUXILIARY SYSTEM

The auxiliary system consists of a hand pump, a system selector valve, and a manual hydraulic pressure dump system. The system selector valve, located adjacent to the hand pump, is a two position manually controlled valve. With the selector valve in the EMER GEAR position, the valve is closed and hand pump pressure is directed to the right hand nose gear actuator and the main gear inboard actuators. With the selector valve in the NORM GEAR position, the valve is open. The manual hydraulic pressure dump system consists of two valves in the power pack that shut off flow from the landing gear selector valve and dump fluid from the retract end of the gear actuators to the reservoir. The system is controlled by a lever located adjacent to the copilot’s inboard seat track.

WARNING LIGHTS

Two red warning lights on the annunciator panel and a pressure gauge on the instrument panel are used to monitor the hydraulic system. Each warning light is controlled by a pressure switch on the output side of each engine driven pump. The pressure gauge is connected to a shuttle valve. The shuttle valve allows the gauge to display main system pressure or auxiliary system pressure, whichever is greater.

EXCESSIVE HYDRAULIC PRESSURE INDICATIONS

Indicated hydraulic pressure above the normal operating range of 1700 to 2100 psi might be caused by:

• An indicating system malfunction, • A malfunctioning hydraulic pump • A blocked return line.

In either of the first two cases, the pilot cannot clear the difficulty. Hydraulic system pressure relief valves should prevent a malfunctioning pump from over‐pressurizing system plumbing during the remainder of the flight. The difficulty and its duration should be reported to a maintenance organization. A common occurrence of high indicated hydraulic pressure follows attempts to retract the landing gear with the hydraulic hand pump engage valve rotated to its forward position. In this case, retract pressure exists in all landing gear actuators and lines and emergency extension fluid is trapped between the emergency extension actuators and the hand pump selector valve and pressure indicator.

Neither full retraction of the landing gear nor elimination of the excessive hydraulic pressure will occur until the hand pump valve has been returned to its normal position.

HYDRAULIC FLUID SHUTOFF VALVES

Two lever lock toggle switches on the center pedestal control the motor operated hydraulic fluid shutoff valves located in each nacelle aft of the firewall. The hydraulic fluid shutoff valve lights are on the lower left and right of the sub annunciator panel. These lights will illuminate any time the valves are moving from the open to closed or closed to open positions. The lights are “in transit lights” only and do not reflect the precise position of the hydraulic shutoff valves.

Revision: Original Aug 1,2013

GO/FCOM/SA227‐SERIES/VTM

AIRCRAFT SYSTEMS HYDRAULIC

SA227‐ SERIES/FCOM/VTM

INTENTIONALLY LEFT BLANK

Revision: Original Aug 1,2013

GO/FCOM/SA227‐SERIES/VTM

6.29.6