BO 105 Hydraulic System LOCATION OF HYDRAULIC BOOSTER

BO 105 Hydraulic System

LOCATION OF HYDRAULIC BOOSTER UNIT Located on the right side of the fuselage under an access panel. The unit is completely self contained with the only hoses being from the transmissions mounted twin pumps

BO 105 Hydraulic System Overview Ø Located on left side of fuselage. Ø Boosts manual control inputs. Ø Two systems for redundancy. Ø Hydraulic pack can be removed without removal of hydraulic line or hose fittings. Ø Has external couplings for GPU or manually operated hydraulic unit. Boosted Output Manual Input

HYDRAULIC SYSTEM Fluid Reservoirs Low pressure filter indicators High pressure filter indicators Micro-switches Shuttle valve Control Inputs System 1 (Primary) System 2 (Back-up)

BO 105 CBS System Concept of the Parallelogram Hydraulic System Points C and D represent the points that you can influence with your control inputs D C F B E A Points A pivot and Bpoints represent points Points F and E represent the aboutthe which AB and CD move. These points sit on the control sliders controlled by for theboth dualboostcylinders. They can move the control sliders slightly right and left to accommodate selection of the path for the high pressure fluid which will control the boost pistons. To sum this, you move CD, and therefore move EF. This movement of EF hydraulically controls the opposite movement of AB to influence of the rotor system.

LOCATION OF HYDRAULIC TEST SWITCH TWO POSITION SWITCH: HYDR RESET

BO 105 CBS System Pressure Switch Location Electrical Connection Hi Pressure Inlet System 1 Pressure Switch System 2 Pressure Switch

BO 105 CBS System Reservoirs and Low Pressure Filters Ø System 1 Reservoir (Sys 2 identical) Ø Reservoir Housing Ø Quantity Indicator Ø Filter Pop-out Button Ø Uses high pressure from the pump to maintain a positive pressure on the fluid

BO 105 CBS System Reservoirs and Low Pressure Filters Ø Reservoir contains two pistons: Ø Low Pressure Ø High Pressure Ø Fluid waiting in the Reservoir is pressurized by the Low pressure piston. TO PUMP Ø High pressure fluid from the pump forces the low pressure piston to compress the reservoir.

BO 105 CBS System Twin Hydraulic Pumps Ø Two separate pumps driven at the transmission Ø Provide contant pressure Ø Variable Volume Ø Each pump contains four lines: Ø Feed line-from the reservoir to the pump Ø Output line-high pressure to the system Ø Case drain line-fluid is allowed to pass around the pistons and is used to lubricate and cool the pump Ø Seal drain line-allows any high pressure leakage at the input shaft to escape overboard and prevent gearbox contamination. (not displayed in diagram)

BO 105 CBS System Pump Schematic Ø Piston assembly is turned by the transmission Ø Bottom of each piston is fixed with a ball joint Ø The backplate is fixed to the piston assembly but can vary its angle to deliver a variable volume at the same pressure ØAs the pistons turn and descend, they draw in fluid from the reservoir ØThe pistons pass the cutoff plate where the fluid becomes trapped ØThe pistons then rise, pushing the fluid into the outlet and into the system under pressure. ROTATION

BO 105 CBS System Solenoid Valve Spring Port to the Shuttle Valve Control Piston High Pressure Port Return Port (to the low pressure side) EMERGENCY OPERATIONS NORMAL OPERATIONS Electro Magnet Active Electro Magnet standby Magnet High pressure is. Electro routed to the low pressure side

BO 105 CBS System Shuttle Valve Shuttle valve-valve Selector Valve Operates assembly in both valve blocks Controlled thefor position Surface by area Systemof 1 the is Shuttle Valve bell crank greater thanthru the Surface area for System 2 power Normally allows hydraulic from. Connected System 1 totopower flight a bell the crank controls attached to the Selector Valve If System 1 is active, System 2 will be closed.

BO 105 CBS System Shuttle Valve HYD 1 System 1 has more on the valve thanthe If System 1 pressure fails, surface Systemarea 2 pressure will force 2 and force valve to the right valve to. System move left andwill open thethe valve in #2 Valve Block selecting System 1 to provide pressure hydraulicto power. allowing System 2 to provide hydraulic the aircraft

BO 105 CBS System Valve Block

BO 105 CBS System Valve Block Components Test Screw – allows main Limiting Valve (pressure Check Valve – Spring loaded pressure to around the regulator) – pass Adjustable spring ball type used to prevent regulator andused the check valve loaded valve to allow extreme pressure Selector Valve – controlled by for testing purposes. excess pressure toloads bleedcaused into by loading on therotor shuttle to switch hydraulic low pressure side asboost a cylinder from backshould feeding power from System 1 to a to safety precaution the System 2. highpumps. pressure condition exist. High Pressure Filter – Cleans the hydraulic fluid passing to High Pressure Filter the cylinder. Highboost Pressure Filter Bypass – Indicator assembly – the In the event of a total In filter event of abypass filter clog, the will open and differential pressure will force allow pressure to continue to the assembly to push down the boost cylinder. and pop out the red clog indicator.

BO 105 CBS System Valve Block PE Valve Block Operation In event that theinfilter During normal operation PEthe (High Pressure fromwith should clog, high pressure the Filter unclogged, pump) –partially high pressure enters on front and back side of pressure fluid passes through thethe valve block and moves to Return (Low Pressure) from the filter will This on way to be thedifferent. boost cylinder. theits check valve and limiting the boost cylinder travels up differential pressure will cause valve through the valve blocktoon its the clogging indicator The check opens and. This way back tovalve the reservoir. extend Additional fluid pressure travels around allows theprovides high path also a way for In the event that the filter to the bypass valve enters the shuttle orifice the Limiting valve to dump should completely clog, and the indicator pin assembly. on to the high pressure excess pressure back into the pressure on the back side of In condition, filter. lowthis pressure side. pressure is the filter unusable. equal on will bothbesides of the The limiting valve stays Should this. The happen, the closed assembly. indicator will since it only opens when bypass willnor open allow not extend theand bypass pressure is than pressure to greater travel into the open normal. boost cylinder to prevent a loss of hydraulic power. R (to the reservoir) R P

BO 105 CBS System Valve Block Check Valve and Limiting Valve PE Valve Block Operation In the event of higher than normal pressure on the high pressure side, the Limiting In the event of high rotor loads valve will open allow excess sending a high pressure surge pressure to bleed over into the back through the high low pressure side. This pressure system, the check prevents excessive pressure valve will close and block the from damaging other surge from traveling back components down stream. through the system. Regulated pressure still travels down stream, but all excess pressure is bled into the low pressure system. R (to the reservoir) R P

BO 105 CBS System Boost Cylinder

BO 105 CBS System Boost Cylinder Components High Pressure – Enters Actuator Housing – twothe ofboost these cylinder after are passing through the assemblies mounted valve block. each Usedother to move the boost opposing piston and hold the bypass pistons in position. Boost Piston – directly Low Pressure – After being usedon to connected to the boost piston produce work on the mainthis rotor, low the opposing cylinder, pressure fluid provides a dynamic piston uses high pressure seal on the boost piston, then travels hydraulic fluid to overcome through the valve block on its way to aerodynamic the reservoir. forces to control your inputs into the main rotor Bypass Pistons – Normally held closed high–pressure fluid, Controlwith Slider based on its these pistons allow fluid position, it controls thetrapped flow ofin the boost during fluid a hydraulic high and cylinder low pressure to failure to pass freely from one the boost piston. chamber to another.

BO 105 CBS System Boost Cylinder Operation When you make a flight control input, you first move the control slider. This opens a port to direct thethe fluid to travel to the Moving flight controls in the boost piston and away from opposite direction produces the boost piston to piston the same result. Theback boost reservoir. moves the opposite direction. When youpiston stop moving The boost moves the flight controls, the boost opposite the control sliderpiston and will continue to move continues to move until you it closes the control stop making a input. slider The and boost returns the fluid to to move a non-until piston continues moving state. closes the control its movement slider and returns the fluid to a non-moving state inside the cylinder. Fluid at rest and. Operations becomes dynamic Normal after start.

BO 105 CBS System Boost Cylinder Operation Boost Cylinder Bypass Mode Should a HYD System 1 failure As discussed earlier, these occur, willheld be providing bypass. System pistons 2 are in pressure to the Influid this position by highsystem. pressure event, there must. When be a way from the pump. that for the boost cylinder allow fluid to disappears in atohydraulic failure, travel freely both nothing will between hold them in sides Without of the boost piston. position. Back pressure caused such system, damage by thea movement of the could boost occur System 1 components pistonto will open the bypass as trapped fluid would be forced pistons. This provides a short back against slider and easy paththe forcontrol the trapped which the boost fluid towould traveldamage and prevent piston. To remedy this problem, dangerous back pressure from these bypass pistonsthe have been traveling up through system. incorporated.