HYDRAULIC POWER CH 29
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ATA 29 HYDRAULIC POWER TABLE OF CONTENTS: RAT CONTROL LOGIC ....................................................................... 54 HYDRAULIC POWER TABLE OF CONTENTS ..................................... 2
POWER TRANSFORMER UNIT (PTU) STAB TRIM .......................... 56
INTRODUCTION ................................................................................... 4
PTU SYSTEM ...................................................................................... 58
HYDRAULIC SYSYTEMS ..................................................................... 6
PTU CONTROL LOGIC ....................................................................... 60
SERVICING ........................................................................................... 8 GROUND POWER CONNECTIONS................................................... 10 PRESSURE TRANSMITTER LOCATIONS......................................... 12 FLIGHT COMPARTMENT CONTROLS & INDICATIONS .................. 14 QUANTITY INDICATING SYSTEM ..................................................... 16 RESERVOIR TEMPERATURE INDICATING...................................... 18 HEAT EXCHANGER ........................................................................... 20 TYPICAL LEFT / RIGHT HYDRAULIC FLOW DIAGRAM................... 22 LEFT / RIGHT SYSTEM COMPONENT LOCATIONS........................ 24 ENGINE DRIVEN PUMP (EDP) LEFT & RIGHT CONTROL .............. 26 EDP CONTROL - LEFT AND RIGHT SYSTEM .................................. 28 EDP SUPPLY SHUTOFF VALVE - LEFT & RIGHT SYSTEMS.......... 30 ALTERNATING CURRENT MOTOR PUMP (ACMP) ......................... 32 L / R ACMP CONTROL - PRESSURE AND OVERHEAT IND............ 34 CENTER SYSTEM DIAGRAM ............................................................ 36 CENTER SYSTEM COMPONENTS ................................................... 38 CENTER SYSTEM ACMP ELECTRICAL CONTROL ......................... 40 AUTOMATIC ISOLATION OF ACMP NUMBER 1 .............................. 42 AIR DRIVEN PUMP (ADP) COMPONENTS ....................................... 44 ADP CONTROL LOGIC....................................................................... 46 ADP OPERATION ............................................................................... 48 RAM AIR TURBINE (RAT) .................................................................. 50 RAT OPERATION ............................................................................... 52
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INTRODUCTION Location
An Air Driven Pump (ADP) is the demand pump in the center system. Air power comes from the airplane pneumatic system, which in turn may be supplied by engine bleed, APU or a ground source such as an air cart.
The three hydraulic systems are identified by location. They are the left, center, and right systems.
A Ram Air Turbine (RAT) pump in the center system which serves as an emergency source of hydraulic pressure is powered by the slipstream.
The left system is located in the left engine strut and contains approximately 17 gallons of hydraulic fluid. The center system is located in or near the right main wheel well and contains approximately 40 gallons of fluid. The right system is located in the right engine strut and contains approximately 20 gallons of hydraulic fluid. This equates to a total capacity of approximately 77 gallons. Multiple Systems The three systems - left, center, and right - have no interconnection. They are color-coded on their tubing runs for ease of identification: Left = Red Center = Blue Right = Green Multiple Pressure Sources Two Engine Driven Hydraulic Pumps (EDP) are used, one on each engine. These are primary pumps in the left and right systems. Four Alternating Current Motor Pumps (ACMP) are used. Two serve as primary pumps in the center system, while one each serves as the demand pump in the left and right systems.
LEFT SYSTEM COLOR CODE - RED ONE EDP ONE ACMP RESERVOIR, FILTERS (IN HYDRAULIC BAY IN STRUT)
RIGHT SYSTEM COLOR CODE - GREEN ONE EDP ONE ACMP RESERVOIR, FILTERS (IN HYDRAULIC BAY IN STRUT)
CENTER SYSTEM COLOR CODE - BLUE TWO ACMP ONE ADP ONE RAT RESERVOIR, FILTERS (IN OR NEAR RIGHT MAIN WHEEL WELL)
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HYDRAULIC SYSTEMS General Each of the three separate hydraulic systems operates with an approximate pressure of 3000 PSI. Any of the acceptable BMS 3-11, type IV fluids such as Skydrol may be used.
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SERVICING Location The reservoir service station is located in the right-hand aft body fairing area immediately aft of the RH wheel well. Purpose The reservoir service station provides convenient single point servicing for checking and maintaining fluid levels in all three hydraulic reservoirs. Components A four-position selector valve and switch is controlled by a single lever that selects the reservoir to be serviced and to be indicated on the hydraulic quantity gauge. Note:
To attain a proper fluid level in the reservoirs, the reservoirs must be serviced with all landing gears down, gear doors closed, steering and flight controls neutral. When servicing right system the brake accumulator pressure gage must read at least 2500 psi.
The hydraulic quantity gauge is calibrated in percent of full increments (110%=1.1) with a green band between .80 and 1.1 indications. Two sight glasses are installed on each reservoir. The lower REFILL sight glass gives indication to replenish reservoir. The upper OVERFILL sight glass gives indication to drain reservoir to FULL level. A pressure-fill port, service filter, and a hand pump with handle and suction hose are also located in the reservoir service station. CAUTION: DO NOT EXCEED 150 PSI FILL PRESSURE WHEN SERVICING HYDRAULIC RESERVOIR. EXCESSIVE PRESSURE COULD DAMAGE RESERVOIR.
WARNING: CARE SHOULD BE TAKEN NOT TO OVERFILL THE HYDRAULIC RESERVOIR. OVERFILLING CAN CAUSE HYDRAULIC FLUID TO ENTER THE PNEUMATIC DUCTING AND THE AIR CONDITIONING PACKS RESULTING IN SMOKE AND NOXIOUS FUMES ENTERING THE FLIGHT DECK AND PASSENGER CABIN. REPEATED HYDRAULIC CONTAMINATION OF THE PNEUMATIC SYSTEM CAN ALSO RESULT IN DAMAGE TO TITANIUM DUCTS.
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GROUND POWER CONNECTIONS General Ground power connections consisting of quick disconnects for pressure and return lines are provided for each hydraulic system. These connections are the attachment points for an external hydraulic pressure source. The left and right hydraulic systems each have two sets of ground power connections. One set is in the engine strut hydraulic bays. The pressure connection is on the EDP filter module and the return connection is on the filter module. The second set is in the aft right wing/body fairing for the right system and on the keel beam between the wheel wells for the left and center systems.
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PRESSURE TRANSMITTER LOCATIONS General The three hydraulic systems each have an independent system for sensing pressure. Separate circuit breakers provide electrical power to interchangeable transmitters. Pressure signals are sent to EICAS computers. Then the computers furnish EICAS display with hydraulic pressure on the ELEC/HYD maintenance page only. Pressure Transmitter Locations The left and right hydraulic system Pressure Transmitters are located on the inboard side support rib, of the Inboard Aileron. Access these by lowering the Training Edge Flaps, they are located near the rear spar. The hydraulic system Pressure Transmitter for the center system is located on right-hand main gear wheel well keel beam. It is just above the #1 Alternating Current Motor Pump (ACMP) Pressure Isolation Valve.
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FLIGHT COMPARTMENT CONTROLS & INDICATIONS Location/Orientation The control panel for hydraulic systems is located on the left side of the P5 Overhead Panel. The upper section of the control module has system Low Pressure and Reservoir low quantity amber lights. The lower section has the control switches for the Primary and Demand Pumps along with lights for pump and system conditions. System Indications The left and right “SYS PRESS” lights through a relay controlled circuit, will illuminate at 1900 PSI or less and go off at 2400 PSI or more if the Engine Driven Pump (EDP) is on; and will illuminate at 1300 PSI or less and go off at 1700 PSI or more if the EDP is off. The center “SYS PRESS" light illuminates at 1300 PSI or less and goes off at 1700 PSI or more from a separate independent low pressure switch. The "QTY" lights illuminate if the respective reservoir fluid quantity is 48% or less of the normal full amount. All four pump "OVHT" lights illuminate at 230oF or more and go off at 185oF or less. The EDP overheat is Case Drain fluid temperature while Alternating Current Motor Pump (ACMP) overheat is Motor Case fluid temperature. Primary Pump Switch The Primary Pump Switches are square alternate action switch lights with an "ON" legend visible when the switch light is latched in and an amber pump low "PRESS" light. Demand Pump Control The Demand Pump Switches are rotary, three position, "OFF", "AUTO",and "ON" switches. In "AUTO" the pump runs on demand, for example, when the primary pump is unable to maintain system pressure. The pumps run continuously in the "ON" position. In the left and right systems "AUTO" controls the ACMP by a pressure switch sensing system pressure - 1900 PSI is "on" and 2400 PSI or more is "OFF", with time delays to reduce pump cycling. In the center system "AUTO" controls the Air Driven Pump (ADP) by the same pressure settings. The ADP is also controlled by Landing Gear, Flap/Slat and Spoiler handle position inputs to meet the high hydraulic flow demands of these systems during take-off, approach and landing.
The left and right Demand Pump "PRESS" lights illuminate at 1300 psi or less and go off at 1700 psi or more. The center Demand Pump "PRESS" light illuminates at 1900 psi or less and goes off at 2400 psi or more. The Demand Pump "OVHT" lights operate at the same temperatures as the primary pumps with the left and right ACMP sensing Motor Case fluid temperature while the center "ADP'' senses Case Drain fluid temperature. EICAS Display Units (P2) Hydraulic system messages are displayed on the EICAS display unit. Aft Control Stand (P8) The engine fire handles control fluid supply to the engine driven hydraulic pumps and pump de-pressurization solenoid. Side Panel (P61) Flight control shutoff valve switches control operation of 6 valves that can isolate hydraulic flow to the wing and tail systems. Ram Air Turbine (RAT) A RAT control switch is located o the P-5 Engine Start Panel, and is used for manual deployment. This switch also indicates both “PRESS” and “UNLKD” conditions for the RAT
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QUANTITY INDICATING SYSTEM Purpose An all solid state hydraulic quantity monitoring system provides reservoir fluid level information for each system. Components A capacitance probe in each reservoir senses fluid level. As fluid level changes, the amount of the probe immersed in fluid will vary thus affecting the probe capacitance. Probes in the left and right reservoirs are interchangeable. A larger probe is used in the center system reservoir. The Hydraulic Quantity Monitor is located on the E2-4 shelf in the Main Electronics Compartment (MEC). The Hydraulic Quantity Monitor provides conditioned signals to the EICAS computers for fluid level indication, the Remote Quantity indicator in the hydraulic servicing station in the right wing body fairing, the "QTY" lights on the P5 overhead panel, and the automatic isolation of reserve brakes and steering. Operation Analog output signals from the Hydraulic Quantity Monitor are digitized by the EICAS computers and displayed on the EICAS status and maintenance pages as hydraulic quantity in terms of percent (%) of full. The decimal 1.00 indicates a full reservoir. If the reservoir is filled to 1/4 above the full level (1.22), a magenta overfill message "OF" will be displayed next to the quantity indication on both the status and maintenance pages. The "OF" message will be displayed only when the airplane is on the ground. When the fluid level falls to .75 and lower a magenta re-fill "RF" message indicating need for refill is added to the decimal display on EICAS (.75 RF ). If the fluid level falls to .48 and lower an amber "QTY" light on the P5 overhead panel is illuminated and an advisory "(L,C,R) HYD QTY" message is displayed on the upper EICAS.
Two sight glasses on each reservoir also indicate fluid status. Absence of fluid at the lower sight glass indicates the need to refill. Fluid appearing in the upper sight glass indicates an overfill condition. Dispatch Deviation HYD QTY (EICAS or Low QTY Lights.) "INOP": • Check applicable Hydraulic System reservoir level for proper fluid quantity using the fill indicator at the fill station. • A sight gauge installed on each reservoir may be used to check the reservoir fluid level if the fill indicator at the fill station is inoperative.
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RESERVOIR TEMPERATURE INDICATING Operation A variable resistance temperature transmitter is mounted on each hydraulic reservoir. As the hydraulic fluid temperature changes, the EICAS computer measures the change in resistance and indicates the temperature on the lower EICAS display. The left EICAS computer controls the temperature indication for the left and center reservoirs while the right EICAS computer controls the right reservoir temperature indication. This system is provided for maintenance troubleshooting and high reservoir temperatures will not result directly in other fault annunciation. Reservoir temperature indication is shown on the EICAS ELEC/HYD maintenance page in degrees centigrade.
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HEAT EXCHANGER Description Three identical heat exchangers cool case drain fluid for all hydraulic pumps except the RAT. For adequate heat dissipation, a minimum of 600 gallons of fuel must remain in each wing fuel tank. Locations The heat exchangers are installed in the inboard ends of the left and right wing fuel tanks as indicated: • Left hydraulic system, WS 288 on stringer 2, 3, 4 and 5 LH wing • Center hydraulic system, WS 288 same stringers, RH wing • Right hydraulic system, WS 313.5 same stringers, RH wing They are mounted on angle strips on top of stringers.
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TYPICAL LEFT / RIGHT HYDRAULIC FLOW DIAGRAM Flow Path A reservoir pressurization module maintains a head pressure in the reservoir. Fluid flows to the Engine Driven Pump (EDP) is through a reservoir standpipe. The EDP provides 3000 psi hydraulic fluid to operate right system components. A fire switch operated supply shutoff valve in this supply line can be closed to prevent fluid from going to the engine driven pump in the event of an engine shutdown due to fire. EDP case drain fluid is used for lubrication and cooling of the pump. Pressure and case drain outputs are filtered in a common module. Case drain fluid is cooled in a fuel cooled heat exchangers. An Alternating Current Motor Pump (ACMP) is a demand source of system pressure. A separate filter module filters ACMP case drain and pressure output. Pump pressures and system pressure are monitored by pressure switches. System pressure is also monitored by a pressure transducer and transmitted to the EICAS computers. System fluid returning to the reservoir passes through a return filter. Loads Right system pressure is provided to the: • • • • • • •
Ailerons Spoilers Lateral Central Control Actuators (LCCA) Rudder Elevator autopilots and Power Control Actuators (PCA) Normal brake system Power transfer unit motor
A motor-operated shutoff valve provides control of fluid flow for the Engine Driven Hydraulic Pumps (EDP). The hydraulic lines to the tail (empennage) area and the wing units have isolation valves for maintenance use. If loss of both hydraulic systems occurs for Stabilizer operation, a Power Transfer Unit
(PTU) pressurizes left system return fluid and provides it to the stabilizer control module. Left Hydraulic System The left hydraulic system is similar to the right system. Check valves and fuses are installed in the left system rudder and elevator pressure and return lines to protect the left hydraulic system in the event of a loss of a horizontal or vertical stabilizer. Loads The left hydraulic system supplies power for primary flight controls and some secondary controls. Ground Power Connection Ground hydraulic power connections are located on the EDP and return filter modules in the aft part of the engine strut.
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LEFT / RIGHT SYSTEM COMPONENT LOCATIONS Engine The Engine Driven Pump (EDP) is located on the forward, left side of the Accessory Gear Box. Aft Engine Strut The reservoir, EDP Supply Shut Off Valve, Alternating Current Motor Pump (ACMP), return filter module, EDP filter module, ACMP Filter Module, Reservoir Pressurization Module, and ground service connections are all located in the aft engine strut area.
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ENGINE DRIVEN PUMP (EDP) LEFT & RIGHT CONTROL EDP Location Each EDP weighs approximately 38 pounds and is located on the engine gearbox. EDP Connections Pressure and case drain hoses have check valve fittings at the pump, while the supply hose is connected by a self sealing disconnect. Compensators Valve and Depressurization Solenoid The spring in the compensator valve operates the valve to direct flow to the control piston to maintain system pressure at approximately 3000 psi during normal operation (no flow). The EDP has a maximum flow rating of 37 gpm at 3700 rpm at 2850 psi. Pump output is approximately 24 gpm at idle engine speed. The pump is depressurized (no flow condition) by powering a solenoid operated valve. This directs pressure to the compensator valve to reduce yoke angle and to the blocking valve to cut off the hydraulic output. The solenoid may be powered by the pump control switch (P-5) in the OFF position or by using the fire handle Secondary Pressure Sources (System Demand) The left and right hydraulic systems each have an Alternating Current Motor Pump (ACMP) as a demand source of pressure. These (pump) sources are triggered "ON" when the primary pumps cannot maintain sufficient pressure. In the left and right systems, each ACMP rated at 7 gpm. These are identical to and interchangeable with the ACMP'S used in the center system as primary pumps.
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EDP CONTROL - LEFT AND RIGHT SYSTEM EDP Push Switch The control switch for the EDP is a square shaped alternate action push-button switch on the P5 overhead panel. Both the white "ON" mechanical flag and the amber "LOW PRESS" light are located on the face of the switch. Function As the pump is switched to the "OFF" condition, the white "ON" is hidden by a mechanical shutter and the pump depressurization solenoid valve is energized to close and prevent further fluid flow to the system. The pump will continue to run as long as the engine rotates. There is no time limit to pump operation while depressurized as long as a supply flow to the pump is available. The pressure light is always active and will illuminate when the pump is depressurized or pressure at the pump outlet is low (at or below 1900 psi). An EICAS advisory message will identify the pump (i.e., L HYD PRIM PUMP).
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EDP SUPPLY SHUTOFF VALVE - LEFT & RIGHT SYSTEMS General An Engine Driven Pump (EDP) supply shutoff valve is located at the forward end of each engine strut bay. It is mounted on the engine strut aft bulkhead. Access is through the engine strut left access panel. Operation The two position valves are electrically operated and are normally open. Valve position is controlled through the associated engine fire switch and is controlled with 28vdc power from the battery bus. When the valve is selected closed, the EDP depressurization solenoid is also energized. A red valve position indicator extends from the side of the valve/motor drive housing to show valve position. The valve cannot be manually operated. CAUTION: PUMP OPERATION OF MORE THAN 5 MINUTES WITH THE VALVE CLOSED AND ENGINE TURNING MAY DAMAGE THE PUMP. SEE THE MAINTENANCE MANUAL FOR INSPECTION PROCEDURE.
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ALTERNATING CURRENT MOTOR PUMP (ACMP)
Secondary Pressure Sources (System Demand)
Primary Pressure Source
The center system Air Driven (ADP) pump, is rated the same as primary (EDP's) in left and right systems, but are not interchangeable. . Also in the center system has a Ram Air Turbine pump (RAT) rated at 11.3 gpm, used to power flight controls in emergencies only.
The center system has two Alternating Current Motor pumps (ACMP) rated at 7 gpm each as it’s primary hydraulic source. General Description ACMPS act as demand pumps in the left and right hydraulic systems to augment the Engine Driven Pump (EDP) and provide hydraulic power for ground systems tests when the engines are not operating. Two ACMPs are the primary pumps in the center hydraulic system. The 4 pumps are identical and interchangeable. Two types of pumps are available, Abex or Vickers. The pumps are similar in output and operation. Both are variable displacement, pressure compensated, constant horsepower hydraulic pumps. The electric motors are 115 volt three phase, continuous duty, explosion proof units. They are fluid cooled and each has a thermal switch that closes at 225°F for overheat indication. The AC motors draw approximately 45 amps at maximum power and approximately 167 amps peak starting current per phase. The ABEX ACMP has an external ripple damper to smooth the pump output. It is rated at 6 GPM at 2850 PSI at 5700 RPM. Below 2850 PSI the pump is compensated so that pump delivery will increase to 12 GPM at 1200 PSI. The Vickers ACMP has an internal ripple damper. It is rated at 7 GPM at 2850 PSI at 5700 RPM. Below 2850 PSI, the pump is compensated so that pump delivery increases to 14 GPM at 1500 PSI. Maintenance Practices Continuous pump operation is possible when the system heat exchanger is in a fuel tank containing a least 4020 lbs of fuel (600 gal., 1827 kg). If the fuel tank contains less than 4020 lbs limit operation to 10 minutes followed by a minimum of 20 minutes cooling. Stop pump operation if hydraulic reservoir fluid temperature exceeds 100°C or the pump overheat light/message illuminate.
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L / R ACMP CONTROL - PRESSURE AND OVERHEAT INDICATION Alternating Current Motor Pump (ACMP) OFF or ON The ACMP low pressure light (L9) is connected to the ACMP low pressure switch (S30). It is illuminated when the pump switch (S7) is in the “OFF” position and when the pressure is below 1300 PSI with the switch “ON”. The system low pressure light is connected to on the Engine Driven Pump (EDP) filter module. ACMP Auto Mode When Engine Driven Pump (EDP) pressure drops to 1900 psi for longer than 0.3 second, the EDP low pressure switch turns on the ACMP. The on control relay latches on a ground through relay (K126). This relay closes a circuit thru (K128) ACMP Off Control relay, energizing the power relay in the ACMP Electrical Control Unit (ELCU M896) turning on the ACMP. The EDP low pressure sense relay (K127) switches the system low pressure light (L3) from pump control pressure switch (S32) to the ACMP low pressure switch (S30). The EDP low pressure light (S4) always responds to the EDP pressure switch (S31) regardless of the position of the ACMP control switch (S4). If pressure at the ACMP low pressure switch (S30) drops below 1300 psi, both the ACMP low pressure light (L9) and system low pressure light (L3) illuminate. The ACMP low pressure light (L9) is connected to the pump control pressure switch (S30) when the ACMP is not running. When the ACMP turns on, the ACMP On control relay (K126) switches the ACMP low pressure light (L9) to the ACMP low pressure switch (S30). When the EDP pressure is restored above 2400 PSI the EDP pressure sense relay (K127) is de-energized enabling the ACMP OFF control relay (K128) to energize after a 15-second time delay. As the ACMP OFF control relay (K128) energizes, it interrupts the holding circuit to the ACMP ON control relay (K126) turning off the ACMP.
ACMP Anti-cycle Protection The anti-cycle protection circuit in the ACMP ELCU is energized whenever the ACMP demand pump switch (S7) is in either the “AUTO or ON” position. The anti-cycle protection circuit prevents the ACMP from restarting automatically after an ELCU auto shutdown for an electrical fault. To restart the ACMP after an ELCU auto shutdown the anti-cycle protection circuit must first be reset by turning the demand pump switch (S7) to the “OFF” position. Engine Start Left ACMP operation is inhibited on the ground during the engine start cycle on either engine. Overheat Indication ACMP overheat indication is controlled by a temperature sensing switch on the pump which monitors hydraulic fluid temperature in the pump housing. The switch will close at 225 degrees F causing the ACMP overheat light to illuminate and the EICAS advisory message "L DEMAND HYD OVHT" to appear. Takeoff Operation Right System Only When in the ground mode the right ACMP will run continuously whenever the slats are commanded to takeoff either by the flap handle or the alternate position select and slat arming switches, as sensed by the flap/slat electronics unit (FSEU). This is to ensure uninterrupted braking power in the event of a RTO due to right engine failure. Note:
Right system shown in graphic, left system similar.
L/R ACMP CONTROL - PRESSURE AND OVERHEAT INDICATION B767-3S2F Page - 35
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CENTER SYSTEM DIAGRAM Reservoir This reservoir is similar to those in the left and right systems, but it holds more fluid. The center reservoir is a 14.7 gallon container holding 8.6 gal. When full, actual volume may be obtained as status on EICAS; otherwise, low quantity will be indicated by an amber "RSVR/QTY" light. The temperature of hydraulic fluid in the reservoir is available on the EICAS ELEC/HYD maintenance page. Alternating Current Motor Pump (ACMP) The Primary Pumps in the center system are Alternating Current Motor Pumps (ACMP) units with Alternate Action switch lights for control on the P5 panel. Each switch light has an amber low pressure "PRESS" light operating from a switch in the respective ACMP filter module at or below 1300 psi. Overheat "OVHT" amber lights for each ACMP illuminate at 230oF in each motor case. Air Driven Pump (ADP) The Demand Pump in the center system is air driven by a turbine and controlled by a rotary switch with "OFF", "AUTO" & "ON" positions the same as the left and right ACMP'S. The "AUTO" mode is controlled through this select switch and S29 pressure switch in the filter module, or an anticipatory circuit involving Gear, Flaps, Slats and Speedbrake handle. Protection from turbine over-speed is provided by a trip mechanism. Overheating (230oF) of the fluid is detected in the case drain fluid in the filter module. Ram Air Turbine (RAT) The RAT is automatically deployed by low engine n2 rpm (50% or less) on both engines while in flight with airspeed greater than 80 knots. Manual deployment may be performed by an Alternate Action type switch on the P5 overhead panel. A separate pressure switch (1700 psi) in the RAT mode in the right wheel well turns on the green "Press" light in the switch light on the P5 panel for RAT pressures of 1700 psi or greater. The RAT may be retracted, after proper blade orientation, on the ground only. A check valve in the hydraulic line from center system primary and demand pumps makes it possible for the RAT developed pressure to only power primary
flight controls, Stabilizer and Spoilers. A separate relief valve permits RAT overpressure flow to the reservoir. Isolation Valves Two isolation valves may be used to direct below standpipe hydraulic fluid through C1 to the reserve brake and steering system. These valves (reservoir isolation and pressure isolation) are controlled by the reserve brake and steering switch on the P1-3 panel. This switch will also turn on the C1 Hydraulic Pump. Isolation valve failures are indicated by the RSV BRAKE VAL EICAS message. System Pressure The center system pressure transmitter is located upstream of the #1 ACMP Isolation Valve so that the full range of system pressure may be available for crew maintenance surveillance on EICAS even through #1 ACMP has been isolated for reserve brakes and steering. The system pressure light switch is downstream of the pressure line isolation valve and will illuminate as the valve closes unless the ADP or #2 ACMP are on.
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CENTER SYSTEM COMPONENTS Right-Hand Wheel Well Keel Beam Two Alternating Current Motor Pumps (ACMP), Reservoir And Reservoir Pressurization Module, two ACMP Isolation Valves, two ACMP Filter Modules, a system Pressure Transducer, a System Low Pressure Switch, system Return Filter and RAT Control/Checkout Module are located in right main wheel well. Right-Hand Wing To Body Fairing Area The Ram Air Turbine (RAT) and hydraulic reservoir service panel are located in compartments aft of right-hand main wheel well. The reservoir air pressurization service/check-out module for all three hydraulic systems is also located aft of the right wheel well. Left-Hand Wing To Body Fairing The Air Driven Pump (ADP) is located in the compartment just aft of the left main wheel well.
CENTER SYSTEM COMPONENTS B767-3S2F Page - 39
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CENTER SYSTEM ACMP ELECTRICAL CONTROL Power Sources The #1 Alternating Current Motor Pump (ACMP) is always operable with power on the left AC/DC buses. ACMP #1 can also be turned on by the Reserve Brakes and Steering Switch if the pump control switch (S2) is off. The #2 ACMP is only operable when the right AC/DC buses are powered and there are two generators supplying power, in which case either one or both Bus Tie Breakers (BTB'S) will be open. When there is only one source of power, either in flight or on the ground, both BTB's will be closed. When both BTB's are closed, the #2 ACMP can be operated only through secondary contacts in the Electrical Control Units (ELCU) of the other three ACMP'S when the associated ACMP is off. The control circuit through the left hydraulic system ELCU is disabled during engine start. This prevents #2 ACMP from coming on line when the left ACMP drops off during an engine start with only one generator power source available.
CENTER SYSTEM ACMP ELECTRICAL CONTROL B767-3S2F Page - 41
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AUTOMATIC ISOLATION OF ALTERNATING CURRENT MOTOR PUMP (ACMP) NUMBER 1 Purpose Isolation Valves controlled by the Reserve Brakes and Steering Switch provides a means of pressurizing alternate brakes and nose wheel steering using the #1 ACMP and fluid isolated below the standpipe level from the center reservoir. If center system fluid is lost, isolation of fluid occurs automatically at the low quantity warning level. If both center and right hydraulic systems are lost this system allows for regaining brakes and nose wheel steering. If only the center system is lost, steering may be regained while brakes remain on the right hydraulic system. Components Pressure Isolation Valve, Number 1, is a motor driven valve that shuts off hydraulic pressure to all center systems except nose wheel steering and the alternate brake system. Supply Isolation Valve, Number 2, is a motor driven valve that switches the #1 ACMP hydraulic supply from the reservoir standpipe to the bottom of the reservoir to access the reserve fluid supply below the standpipe. Reserve Brakes and Steering switch is a lighted push-button switch containing a white "ON" legend and an amber "VALVE" light located on the P1-3 panel. Reset/Disable switch is a toggle switch on the P-61 panel to reset the automatic isolation system or to disable the auto function while performing ground maintenance.
Operation Actuation of the reserve brakes and steering switch turns on the #1 ACMP, if off, and shows the "ON" legend in the switch. Electric power is first supplied to drive the Supply Isolation Valve to the closed position. When fully closed, the Supply Isolation valve directs power to drive the Pressure Isolation Valve to the alternate position. An amber "VALVE" light in the lower half of the reserve brakes and steering switch will illuminate to indicate a disagreement between the switch position and the position of either valve. If the disagreement exists for 6 seconds an EICAS advisory message "RSV BRAKE VAL" will be annunciated. With the reserve brakes and steering switch in the unlatched position, both the Pressure and Supply Isolation Valves will operate to the closed and alternate positions respectively when center system fluid reaches "LOW" quantity level (48%) and the airplane is in flight. The pump (#1 ACMP) then must be activated by pressing the reserve brakes and steering switch or the #1 ACMP switch. A white "ISOLATION" light on the P-61 right side panel will illuminate when either isolation valve is not in the open (normal) position. While the Reserve Brakes and Steering switch is selected "ON", center system pressure will still be transmitted to the EICAS computer. However the system low pressure switch (S-35) is isolated from pressure causing the center system low pressure light to illuminate and the EICAS “C” level message (Low Pressure) to appear.
ON
28V DC L BUS L15
TO PUMP
ON
P11 CB PANEL
1
NOT OPEN
S33 ACMP C-1 NC
VALVE a SET
RES BRKS & STRG SEL SWITCH (P1-3) 6 SEC TD
MD & T POWER
NC
CLOSE
CLOSED
QTY
1
S1 RES BRK & STRG RESET SW
K1 ISLN VLV RLY 1
NC
P5
ISOLATED w
P 1700 PSI
S33 ELEC HYD GND
L-1
1 2
RETURN ACMP NO. 1
D474 3
PUMP C1 PRESS
AIR
.3 SEC TD
OPEN
K124 (P36) TO EICAS "C HYD QTY"
K2
K4 PWR K5 TD RELAY SENSE RLY M1216 RESERVE BRAKES & STRG HYD SOURCE SELECT MAINT PNL (P61)
P11 CB PANEL
C SYS RESERVOIR
NOT CLOSED
NORMAL
10 SEC TD
HYD QTY 115V AC GND SVC L20 BUS
K3 LOW QTY LATCH RLY
HYD SYS C NO. 2 ISOLATION VALVE
RESET/ DISABLE
L/R EICAS COMPUTERS
NO. 2 ISOLATION VALVE
M
RESET
ON
1
OPEN NOT OPEN
PRESS SW
AUTO
"RSV BRAKE VAL"
OPEN
PRESS a
S2 ACMP C1 SEL SW (P5)
1
P
V111 NO. 2 ISOLATION VALVE, SUPPLY V110 NO. 1 ISOLATION VALVE, PRESS.
OPEN
NC
LOW 'C' SYS
TO RETURN
NOT OPEN OPEN
TO HEAT EXCHANGER
NOT OPEN M
NC
POWER SUPPLY
NOT CLOSED CLOSE
M122 HYD QTY MON (E2-4)
N0. 1 ISOL VALVE
TO SYS (ADP/ACMP NO. 2)
CLOSED
1 HYD SYS C NO.2 ISOLATION VALVE
EICAS PRESSURE INDICATION
NOSE LANDING GEAR ACTUATION
BRAKES
LEGEND
FWD
TO SYS PRESS. LIGHT
M342 HYD SYS C PRESS. XMTR NC
NOSE GEAR STEERING
P
S35 HYD SYS C PRESS.
RIGHT WHEEL WELL KEEL BEAM
AUTOMATIC ISOLATION OF ALTERNATING CURRENT MOTOR PUMP (ACMP) NUMBER 1 B767-3S2F Page - 43
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SUPPLY PRESSURE RETURN AIR
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AIR DRIVEN PUMP (ADP) COMPONENTS General The pump is a single unit with a pressure regulator/shutoff valve and modulating valve to control air which turns a turbine driven hydraulic pump. A muffler is installed in the inlet air duct to the turbine to reduce the noise level, and an exhaust duct directs the "spent" turbine air overboard. Hydraulic Pump The hydraulic pump produces 37 gpm at 2850 psi while turning at 5683 rpm. The Variable Displacement, Constant Pressure pump regulates turbine speed by load and has a compensated cutoff with (0) zero flow at 3025 psi. At low flow, turbine speed is decreased; with 2300 rpm at no load and 5683 at rated load. The ADP pump is driven through a 5.158:1 gear reduction gearbox lubricated with mil 7808 engine oil. The case drain fluid cools the gearbox oil through a heat exchanger in the fuel tank in the right wing.
AIR DRIVEN PUMP (ADP) COMPONENTS B767-3S2F Page - 45
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ADP CONTROL LOGIC
Other Auto Operation
Purpose
ADP operation in "AUTO" is continuous if:
The demand logic circuit controls operation of the pump under different conditions. • ADP Switch "OFF" - no ADP operation • Pump Switch "AUTO" - the ADP runs dependent on the conditions listed below • Pump Switch "ON" - ADP continuous run solenoid is energized and the pump runs continuously Operation (Auto Mode) Various conditions control the ADP operation with the switch in "AUTO"; they are low center hydraulic system pressure, both Alternating Current Motor Pump (ACMP) switch positions "OFF", gear disagree, slat disagree, flap disagree, and speed brake handle armed while on the ground. Low Pressure Operation Low center hydraulic system pressure (1900 PSI) sensed by S29 causes the ADP to run for a minimum of 15 seconds. This condition is controlled by relays K153 & K684. ADP operation is continued for 15 seconds to ensure system pressure is maintained above 2400 PSI.
• • • •
Both center ACMP switches are "OFF" Slats disagree with flap lever position sensed by the PSEU Flaps disagree with flap lever position sensed by the FSEU Landing gear and landing gear lever positions disagree sensed by the PSEU • Speed brake lever "ARMED" with the airplane in ground mode • Hydraulic Generator Commanded “ON”
ADP CONTROL LOGIC B767-3S2F Page - 47
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ADP OPERATION
ADP Over-Speed Annunciators
Operation
The ADP Over-Speed Control Card (M1057), located in the P-50 card file contains three LED'S that annunciate ADP conditions labeled DS 1 - on O/S, DS 2 - AUTO O/S and DS3 - pwr in. Lights DS 1 and DS 2 will illuminate whenever over-speed topping occurs in the relevant mode and is out when speed is reduced back to normal range. The lights will not be on if the centrifugal switch has caused a shutdown to occur. "DS3" is on any time the ADP is operating.
The ADP is turned on by either continuous run or demand run solenoid valves. Control air is supplied from the regulator/shutoff valve at 13 psi through a jet pipe which is positioned by the hydraulic pump Swash Plate and Modulating Valve output pressure. The hydraulic pump swash plate angle is controlled by the pump output pressure. Movement of the swash plate to increase flow deflects jet pipe to "fast" side and opens the modulating valve to increase air flow to the turbine. A large swash plate angle due to low pressure, or high flow demand, increases valve opening to increase pump output. Pump output is 37.0 GPM at 2850 PSI at 5683 RPM. A small swash plate angle from high pressure or low flow demand, reduces valve opening to decrease pump output. Pump output is near 0 GPM at 3025 PSI at 2300 RPM. Over-Speed Control An electronic topping circuit prevents over-speed from a sudden drop in hydraulic pressure. A Monopole Sensor sends a turbine speed signal to the Over-Speed Control Card (M1057) in the P-50 card file. Maximum speed is limited to 6000 - 6600 RPM. An over-speed condition causes rapid interruption (pulse modulating) of the signal to the controlling solenoid. A centrifugal over-speed switch provides over-speed shutdown by closing the regulator/shutoff valve if turbine speed reaches a maximum of 7100 - 7700 RPM. An over-speed shutdown is magnetically latched and the ADP cannot be restarted until the solenoid valve is manually reset by a test/reset switch on the door of the P36 panel in the equipment center. This switch can also be used to test the over-speed shutdown solenoid circuit.
ADP OPERATION B767-3S2F Page - 49
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RAM AIR TURBINE (RAT) General The RAT is an air turbine driven hydraulic pump that provides emergency hydraulic power for the flight controls in the event that power is lost on both engines. The RAT is stowed inside the right aft body fairing. Operation When deploying, the RAT pivots downward to extend the turbine into the airstream. An electric motor drives the unit for both deployment and stowing. The Motor extends and retracts the RAT by rotation of a motor arm and actuation link. A 15 Degree Limit Switch, permits partial retraction of the RAT so that the blade can be locked and the blade centered switch can be closed. Down and Up Limit Switches provide extend/retract motor shutoff at full down or full up travel limits. A Manual Override Switch, located on P5 panel, permits manual selection of RAT extension either in air or on ground. Hydraulic Pump The Abex variable displacement, compensated pump has a rated output flow of 11.3 gpm at 2140 psi at 4165 rpm. Turbine/hydraulic pump speed ratio is 1:1. Turbine Blades Two variable pitch blades are controlled by a counterweight and governor spring inside the turbine hub. Governed speed is 4165 +/-45 rpm at a minimum airspeed of 125 knots. A lock plunger prevents blade rotation when the RAT is in the stowed position, and prevents complete RAT retraction unless the turbine blade is locked in the proper position for stowing. Blade lock and switch activation occurs when the RAT has been retracted 13.5 degrees from the fully-extended position. A Teleflex Cable unlocks the turbine blade and opens the blade lock and centered switch when RAT is extended.
RAM AIR TURBINE (RAT) B767-3S2F Page - 51
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RAT OPERATION Extension Automatic deployment of the RAT is triggered in the air mode only by having low N2 speed (less than 50%) on both engines and an airspeed greater than 80 knots. Manual electric control of extension of the RAT may be performed by a RAT Guarded Override Select switch on the P5 overhead panel at any time, in flight or on the ground. Retraction The retraction of the RAT is possible only on the ground and is triggered by a guarded switch near the checkout module on the keel beam in the right main gear wheel well. The RAT cannot be retracted beyond 15 degrees until the propeller blade is centered with the locking pin in place so that the blade lock and centered switch can complete the retract circuit. Ground Checkout To accomplish the ground checkout of the RAT, the center system must have hydraulic pressure flow capability of 17 gpm or better. The two center ACMP'S both on will not provide enough flow. The ADP or a ground source of hydraulic power must be used. By pulling the handle on the checkout module in the right main gear wheel well, the RAT is back-driven hydraulically. A Tachometer Module has lights to indicate the speed range for governor/RAT check. • Green indicates on speed • Red indicates over-speed • No light Indicates under-speed A lamp test switch is also provided, however the RAT must be rotating in order to test the lamps.
WARNING: CARE SHOULD BE TAKEN WHILE OPERATING THE RAT AS THE BLADES TURN AT A HIGH RATE OF SPEED. BE
SURE TO FOLLOW ALL PRECAUTIONS IN THE MAINTENANCE MANUAL.
RAT OPERATION B767-3S2F Page - 53
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RAT CONTROL LOGIC Automatic Deployment Automatic extension / deployment of the RAT is possible in the AIR mode when both engines are shut down. The electrical drive of the RAT to the deployed position will stop as the motor driven drive arm hits a down limit switch (S365). Any time the RAT is not full up (as limited by the up limit switch S369), The amber unlocked light will illuminate in the M49 module on the P5 panel. The RAT green pressure light will illuminate when its developed pressure is 1700 psi or above. Manual Control Manual electric control of the RAT is with the guarded switch (S7) on (M49) module on the P5 panel. It is possible to do this at any time while on the ground or in flight. For this sequence, a separate Override Limit (down) switch (S501) is used - operating from the motor driven arm. The unlock and pressure lights are always active.
RAT CONTROL LOGIC B767-3S2F Page - 55
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POWER TRANSFORMER UNIT (PTU) STAB TRIM General The power transfer unit (PTU) is a backup system to provide hydraulic power for the stabilizer. If the left and center hydraulic systems are not operational to drive the stabilizer ball-screw hydraulic motors, the PTU enables the right hydraulic system to provide a third power source for stabilizer trim. The PTU components are located in the stabilizer compartment on bulkheads above the stabilizer trim ball-screw mechanism. The PTU system is connected to the left and right hydraulic systems and the left stabilizer trim control module. The system contains the following hydraulic components: • • • • • •
Right hydraulic system shutoff valve module Motor/pump assembly Pressure filter module Case drain filter module - Left hydraulic system isolation valve module Relief valve Check valves
POWER TRANSFER UNIT (PTU) STAB TRIM B767-3S2F Page - 57
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PTU SYSTEM
Relief Valve
Power Transfer Unit
A relief valve, installed between the left elevator feel computer and the left Stabilizer Trim Control Module (STCM), prevents loss of isolated left system hydraulic fluid through the elevator feel port of the left STCM. The relief valve is closed when pressure at the STCM feel computer port is less than 100 psi.
The power transfer unit is commanded ON automatically to provide hydraulic power to drive the stabilizer in the event both left and center hydraulic systems fail. The following components in the power transfer unit (PTU) system provide hydraulic pressure to the left stabilizer trim module from an isolated left hydraulic system supply source. Pressure is supplied by the right hydraulic system pumps. Left System Isolation Valve The isolation valve is installed in the left system pressure line to the stabilizer trim module. The valve has two positions and is operated by a DC motor. When the valve is in the OFF (closed) position, it helps to isolate the part of the left hydraulic system which contains the PTU pump and the stabilizer trim module. When the valve is in the ON (open) position, it permits the usual flow of left system pressure to the stabilizer trim module. Right Hydraulic System Shutoff Valve The shutoff valve is installed in the right system pressure line to the PTU motor. The valve has two positions and is operated by a DC motor. When the valve is in the ON (open) position, it supplies right hydraulic pressure to operate the PTU motor. When the valve is in the OFF position, it removes right system pressure to the PTU motor. The shutoff valve also has a position indicator and manual override lever. Filter Modules Filter modules are installed in the pump pressure and case drain lines. The filters are non by-passable. The pressure filter cannot be cleaned. The case drain filter can be cleaned.
PTU Return Compensator Module The return compensator module is installed in the left system return line from the stabilizer trim module. The return compensator module includes a bypass valve and a compensator that contains about four cubic inches of fluid. When the left hydraulic system is operating correctly, fluid that flows from the stabilizer trim module through the left system return line to the reservoir must flow through the return compensator. Flow through the compensator is initially blocked by the bypass valve. This causes fluid to be pushed into the compensator. When the compensator is full, the fluid pressure in the line increases until it opens the bypass valve to permit flow of fluid through the compensator to the left return system. When a failure in the left hydraulic system causes the PTU system to operate, the left system isolation valve closes. This removes left system pressure from the stabilizer trim module. When the pressure in the stabilizer trim module return line decreases to 45 to 50 psi, the bypass valve in the compensator closes to isolate the PTU system from the left return system. The fluid in the compensator is pushed out by the piston and spring and becomes a source of fluid for the PTU pump inlet.
PTU SYSTEM B767-3S2F Page - 59
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PTU CONTROL LOGIC
Right Hydraulic System Shutoff Valve
System Control
When the left hydraulic system isolation valve is commanded closed, the right hydraulic system shutoff valve is controlled by the control wheel stabilizer trim control switches and the center hydraulic system pressure.
Operation of the PTU is controlled automatically. Power Electrical power from the left 28 vdc bus is used to operate the PTU control relays, the right hydraulic system shutoff valve and the left hydraulic system isolation valve. Left Hydraulic System Isolation Valve When the airplane is in the air, air/ground system No. 2 connects the left hydraulic system isolation valve controls to the left hydraulic system pressure and quantity indication of the left reservoir. The left hydraulic system isolation valve closes under either of the following conditions: • The hydraulic quantity monitored in the left reservoir falls below 0.48 • The left hydraulic pressure produced by both the Engine Driven Pump (EDP) and the Alternating Current Motor Pump (ACMP) is low. If one of these conditions is removed, the left hydraulic system isolation valve remains closed for an additional time of 20 seconds to prevent nuisance signals of short duration from operating the isolation valve intermittently.
Loss of center hydraulic system pressure and a stabilizer electric trim command from either the captain's or the first officer's control wheel switches, cause the right hydraulic system shutoff valve to open and start PTU operation. The right hydraulic system shutoff valve remains open as long as a stabilizer electric trim signal is present and the center hydraulic pressure is low. When the stabilizer electric trim signal is removed, or the center hydraulic pressure is restored, the right hydraulic system shutoff valve is commanded to close.
PTU CONTROL LOGIC B767-3S2F Page - 61
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