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105 Cards in this Set
- Front
- Back
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The Solenoid-operated selector valve aer
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electrically controlled by one or more solenoids contained withing the valve.
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Solenoids are
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electrical devices that can be used to position mechanical units.
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One advatage of electrical control
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is the removal of high-pressure lines from the flight deck.
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The Solenoid-operated slide type selector valve has four ports:
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Pressure, return, and two alternating ports.
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When the slides in a Solenoid-operated slide type selector valve are properly positioned,
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the lands (Flat portions on the slides) will allow fluid to flow from one passageway to another.
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When both solenoids in a Solenoid-operated slide type selector valve are de-energized, what position are is the valve in?
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Neutral
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Solenoid-operated poppet type selector valve, has _____ which are attached to the ____ in the solenoid.
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Poppets; plunger
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When the Solenoid-operated poppet type selector valve is de-energized, the poppets
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are on seat against the return seats.
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Selector valves can be designed to allow the fluid in the alternating lines to have a
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freeflow back to return.
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When a valve is in the full-trail position,
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it allows the fluid ni the alternating lines to have free flow back to return.
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Half-trail indicates
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half of the valve allows fluid to be trapped ni the alternating lines.
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Non-trail
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any fluid in the alternating lines cannot flow back to return.
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Selector valves can be operated...
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electrically and manually.
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Solenoid-operated selector valves with manual override
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has solenoids for normal operation and a manual operation for emergency use.
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The flow-control servo valve is an
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electro-hydraulic valve that will direct fluid-flow to a subsystem or component much like a convetional selector valve.
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The difference between a selector valve and a servo valve is that the servo valve will also
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control the flow of fluid through it.
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The purpose of a hdraulic actuator is to
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transform fluid pressure into mechanical force which can be exerted in a straight line or a rotary motion.
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An actuating _______ is generally used for straight line action, whereas hydraulic ______ are used for rotary action.
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Cylinder; motors
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The actuating cylinder cosists of
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a cylinder barrel, a piston, one or two piston rods, ports, and necessary seals.
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Actuating cylinders are usually...
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double acting (Fluid under pressure can be applied to either sde of the piston to cause movement in either direction)
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What does a Single-Acting actuator use to return to it's original position after operation?
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A spring.
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Blanced-Type actuators are used to
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obtain the same amount of force in either direction.
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Double-Acting Unbalanced actuating cylinders are normally used with...
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landing gear, speed brakes, and weapons door systems.
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Double--Acting Unbalanced actuating cylinders apply
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more force in one direction.
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Double-Acting balanced actuating cylinder's piston rod
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extends through the piston and out both ends of the cylinder.
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The rods in a double-acting balanced actuating cylinder are used to provide
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equal areas on each side of the pistong allowing the same force to be provided in both directions.
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Internal Snubber actuators reduce
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damage to mechanisms by preventing the actuator from slamming into it's end of travel with great force.
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Internal locking actuators do what?
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Lock a hydraulically operated unit in position to prevent it from moving.
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What's the difference in a double-acting unbalanced cylinder and a double acting ball lock actuator?
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The Double-acting ball lock actuator has a locking mechanism at each end of the cylinder that retains the piston in either the exteded or retracted position.
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The Toggle-lock actuator will
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lock itself in the retracted position.
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The toggle-lock actuator can be unlocked...
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manually by pulling a cable attached to the hollow stem of the lock and the rod piston shaft lock.
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Nonautomatic position control systems are used when
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full travel of the actuator is required for each operation of the unit (Landing gear, bomb bay, etc)
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The nonautomatic actuation systems are controlled...
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manually by the operator.
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Automatic position control systems provide...
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automatic control of actuatin mechanisms.
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Automtaic position control systems have follow-up systems, which
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limit the movement to a desired amount automatically.
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The mechanical follow-up system oerates through a
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system of cables and pulleys or rigid linkages.
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The differential follow-up system uses a set of
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opposed gears enclosed in a separate housing from the actuating unit.
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The electric follow-up system consits of four basic items:
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an input transducer, an amplifier, a servo device, and the follow-up transducer.
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Limited rotary actuator provide
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only limited rotary motion as opposed to the continuous rotary motion provided by a motor.
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A rack and pionion actuator consists of a
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rack which moves and causes a pionion gear to rotate.
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When the manual-type poppet selector valve is in the neutral position, which poppets are on seat?
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All the poppets.
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If the cam on the manual poppet selector valve is position 45 degrees from neutral, what will happen?
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One pressure and one return poppet will be forced from their seats.
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Which one of the manual selector valves can be used as a metering valve?
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Slide type
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Why are solenoid-operated valves used instead of manual valves?
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Solenoids permit the position selector valves
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Name Tyo types of Soleniod-operated selector valves.
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Slide and poppet
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What centers the control spools on either the poppet or the slide selector valves?
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A spring
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Why would you want to hav a valve that is designed as a full-trail valve?
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When you want your alternating lines to have free flow back to return
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What does half-trail mean?
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Half the valves allow fluid to be trapped in the alternating lines.
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What is the major difference between a selector valve and a servo valve
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The servo valve controls and directs flow.
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What are three basic types of actuators?
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Single, double unbalanced, and double balanced
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How many pistons are found in a tandem actuator?
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Two
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If a tandem-type actuator is used on the primary flight controls, will it be able to handle the aircraft if one hydraulic system fails?
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Yes.
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Which direction of fluid flow controls the speed of the internal snubber actuator during extension?
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outflow
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What functionWhat forces the actuator's lock balls against the detent?
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The plunger.
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What must happen before the actuator's lock balls are allowed to move out of the detent to unlock the actuator?
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Pressure must be applied to force the locking plunger away from the balls.
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What happens to the locking segments as the actuator piston retracts and applies pressure to the segment retainer?
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The spring behind the piston lips.
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What is the difference between automatic and nonautomatic postion control systems?
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Automatic positions inself back to neutral.
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Which position control system has a follow-up system that limits the movement desired?
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Automatic.
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Which follow-up system neutralizes selector valve operation through the action of an operation arm hooked to a pinion gear and uses a set of gears?
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Differential
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Which follow-up system uses cables and pulleys?
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Mechancial
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Which follow up system holds a servo valve in neutral via a follow-up potentiometer hooked to the control surface sending a signal to an amplifier and works on a servo loop principle?
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Electrical
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Name two types of actuators primarily used for limited rotary motion.
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Vane and Rack & Pinion
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What is the pinion of a rack & pinion actuator normally attached to?
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A moveable object.
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On the vane-type actuator, which vans are connected to the wingshaft?
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The moveable ones.
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Fixed orifices (restrictors) are used in systems to
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limit the speed of movement of items (Wing flaps, landing gears, etc)
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Variable orifices are constructed so that the
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amount of restriction can be adjusted.
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Orifice check valves
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allow normal speed of operation in one direction, but they limit speed in the other.
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The orifice check valve is usually installed in the
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alternating line that carries fluid from the cylinder.
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What's an In-line filter restrictor?
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Contains two wire mesh finger screens used to rpevent dirt from blocking the hole in the orifice on either side of the fixed orifice plate.
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Hydrauli flow regulators' job is to
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keep the fluid-flow at a constant rate.
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Flow regulators regulate fluid flow in
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one direction only.
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Flow equalizer is a unit that
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hydraulically synchronizes the movement of two hydraulically operated cylinders.
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Hydraulic fuses prevent
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total fluid loss from the hydraulic system.
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Pressure reducing valves will
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reduce sytem pressure to a desired level and relieve thermal expansion in the section of the system that it isolates.
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Pressure reducing valves have three ports:
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System pressure port (Connected to system pressure), The resevoir return port (Connected to the system return line) and the reduced pressure port.
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What do shuttle valves do?
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Separate one hydraulic system (or part of a system) from another.
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Where are shuttle valves located?
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As close as possible to the unit to be actuated.
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The body of the shuttle contains three ports:
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Normal system inlet port, Emergency system inlet port, and Unit outlet port
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What does a sequencing system allow?
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One operation to be performed before the rest of a system can operate.
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How can sequencing be controlled?
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Mechanically, hydraulically, and electrically
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How are flopw regulators rated?
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Gallons per minute
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What does the size of the orifice determine in a hydraulic fuse?
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The amount of fluid that will flow through the valve before it fuses
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Which type of fuse automatically resets?
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Type I
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Which type of fuse is held in the fused position by a lock spring and stop rod?
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Type II
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When would a hydraulic system need a pressure reducer?
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When full system pressure is not required
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What is one way you can tell if a shuttle has internal leakage?
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Excessive heating
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What type of sequencing is used for sequencing a mechanical system?
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Mechancial
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In a pressure sequenced system? What provides the sequecing effect?
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Priority valve/balanced relief valve
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What is the purpose of the swivel joing?
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To proved tubing between moving parts
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How many times should you leak-test a swivel? What should you do while testing it?
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3 timers, Rotate it 360 degrees during the test
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What is the advantage of a balanced extension unit over simpler swivels?
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It will extend and retract.
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What does the hydraulic power system do?
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Furnishes the pressures to operate such systems as the landing gear, nosewheel steering, brakes, and flight controls.
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What gives a visual indication of the reservoir fluid quantity?
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The sight-level guage
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What does the suction boost bypass line do?
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Continuously circulates fluid from the suction boost pump back to the reservoir to provide a cooler operating boost pump
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In case of a fire emergency, what shuts off hydraulic fluid supply to the engine driven pump?
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The firewall shutoff valve.
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What kind of circuit cools the hydraulic fluid and keeps the engine-driven pump lubricated?
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A runaround circuit
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What does the low-pressure warning light switch do?
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When pump discharge pressure drops below the low limit, the switch actuates and causes a warning light on the hydraulic control panel to glow.
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What are the two way of closing the suction shutoff and solenoid-operated shutoff valves?
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Pulling the T-handles and placing the engine pump switches to OFF
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When troubleshooting the hydraulic power supply system, you should always...
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follow the applicable TO.
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Why is a vent line filter installed on a reservoir?
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To prevent contamination
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What connects the reservoir to the suction boost pump and why?
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Flexible hose because of severe vibrations
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Why does the suction boost pump have a bypass line installed?
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Cooler operation
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How are the hydraulic supply lines to the engine-driven hydraulic pumps pressurized?
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Suction boost pump
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Anytime that you suspect that air is in a system, you must
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bleed the system.
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What does it mean to bleed a system?
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Remove all the air from the system.
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