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发表于 2009-3-20 23:48:17
AvionicBusAvionics RelayOnOffAvionics MasterSwitchLightsPanelPositionBeaconTrimInstrLndg LtRadioXpdrClutchAmmeterMag SwitchLeftMagnetoRightMagnetoStarterRelayEngineStarterBus BarBatteryRelayBatteryBatterySwitchStarterSwitchM/R GearboxPress SwitchReleaseHoldEngageClutchSwitchAlternatorAlternatorSwitchAlternatorControl UnitClutch Actuator(Internal Limit SwitchesShown in FullDisengage Position)24V– +F1 F2–+StartingVibratorRRBothL LOffRetAdvAdvG(Optional Avionics)Figure 5-12. An electrical system scematic like this sample isincluded in most POHs. Notice that the various bus baraccessories are protected by circuit breakers. However, youshould still make sure all electrical equipment is turned offbefore you start the engine. This protects sensitive components, particularly the radios, from damage which may becaused by random voltages generated during the startingprocess.FilterTo CarbCarb HeatCollectorManifoldPipe
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DoorFilterTo CarbCarb HeatCollectorManifoldPipeDoorHeated AirCarb Heat OffCarb Heat OnFigure 5-11. When you turn the carburetor heat ON, normalair flow is blocked, and heated air from an alternate sourceflows through the filter to the carburetor.5-9incorporated to prevent excessive voltage, which maydamage the electrical components. The bus bar servesto distribute the current to the various electrical components of the helicopter.A battery is mainly used for starting the engine. Inaddition, it permits limited operation of electricalcomponents, such as radios and lights, without theengine running. The battery is also a valuable sourceof standby or emergency electrical power in the eventof alternator or generator failure.An ammeter or loadmeter is used to monitor theelectrical current within the system. The ammeterreflects current flowing to and from the battery. Acharging ammeter indicates that the battery is beingcharged. This is normal after an engine start sincethe battery power used in starting is being replaced.After the battery is charged, the ammeter should stabilize near zero since the alternator or generator issupplying the electrical needs of the system. A discharging ammeter means the electrical load isexceeding the output of the alternator or generator,and the battery is helping to supply electrical power.This may mean the alternator or generator is malfunctioning, or the electrical load is excessive. Aloadmeter displays the load placed on the alternatoror generator by the electrical equipment. The RFMfor a particular helicopter shows the normal load toexpect. Loss of the alternator or generator causes theloadmeter to indicate zero.Electrical switches are used to select electrical components. Power may be supplied directly to the componentor to a relay, which in turn provides power to thecomponent. Relays are used when high current and/orheavy electrical cables are required for a particular component, which may exceed the capacity of the switch.Circuit breakers or fuses are used to protect variouselectrical components from overload. A circuit breakerpops out when its respective component is overloaded.The circuit breaker may be reset by pushing it back in,unless a short or the overload still exists. In this case,the circuit breaker continues to pop, indicating an electrical malfunction. A fuse simply burns out when it isoverloaded and needs to be replaced. Manufacturersusually provide a holder for spare fuses in the event onehas to be replaced in flight. Caution lights on the instrument panel may be installed to show the
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发表于 2009-3-20 23:48:45
malfunction ofan electrical component.HYDRAULICSMost helicopters, other than smaller piston poweredhelicopters, incorporate the use of hydraulic actuatorsto overcome high control forces. A typical hydraulic system consists of actuators, also calledPressureReturnSupplyScupperDrainVent ReservoirPumpPressureRegulatorValveQuickDisconnectsFilterSolenoidValveServoActuator,LateralCyclicServoActuator,Fore andAftCyclicServoActuator,CollectivePilotInputRotorControlFigure 5-13. A typical hydraulic system for helicopters in the light to medium range is shown here.5-10igation capabilities, such as VOR, ILS, and GPSintercept and tracking, which is especially useful inIFR conditions. The most advanced autopilots canfly an instrument approach to a hover without anyadditional pilot input once the initial functions havebeen selected.The autopilot system consists of electric actuators orservos connected to the flight controls. The number andlocation of these servos depends on the type of systeminstalled. A two-axis autopilot controls the helicopterin pitch and roll; one servo controls fore and aft cyclic,and another controls left and right cyclic. A three-axisautopilot has an additional servo connected to the antitorque pedals and controls the helicopter in yaw. Afour-axis system uses a fourth servo which controls thecollective. These servos move the respective flight controls when they receive control commands from a central computer. This computer receives data input fromthe flight instruments for attitude reference and fromthe navigation equipment for navigation and trackingreference. An autopilot has a control panel in the cockpit that allows you to select the desired functions, aswell as engage the autopilot.
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发表于 2009-3-20 23:48:57
For safety purposes, an automatic disengage feature isusually included which automatically disconnects theautopilot in heavy turbulence or when extreme flightattitudes are reached. Even though all autopilots can beoverridden by the pilot, there is also an autopilot disengage button located on the cyclic or collective whichallows you to completely disengage the autopilot without removing your hands from the controls. Becauseautopilot systems and installations differ from one helicopter to another, it is very important that you refer tothe autopilot operating procedures located in theRotorcraft Flight Manual.ENVIRONMENTAL SYSTEMSHeating and cooling for the helicopter cabin can beprovided in different ways. The simplest form of cooling is ram air cooling. Air ducts in the front or sides ofthe helicopter are opened or closed by the pilot to letram air into the cabin. This system is limited as itrequires forward airspeed to provide airflow and alsoservos, on each flight control, a pump which is usuallydriven by the main rotor gearbox, and a reservoir tostore the hydraulic fluid. A switch in the cockpit canturn the system off, although it is left on under normalconditions. A pressure indicator in the cockpit may alsobe installed to monitor the system.When you make a control input, the servo is activatedand provides an assisting force to move the respectiveflight control, thus lightening the force required by thepilot. These boosted flight controls ease pilot workloadand fatigue. In the event of hydraulic system failure,you are still able to control the helicopter, but the control forces will be very heavy.In those helicopters where the control forces are sohigh that they cannot be moved without hydraulicassistance, two or more independent hydraulic systemsmay be installed. Some helicopters use hydraulic accumulators to store pressure, which can be used for ashort period of time in an emergency if the hydraulicpump fails. This gives you enough time to land the helicopter with normal controlSTABILITY AUGMENTATIONS SYSTEMSSome helicopters incorporate stability augmentationssystems (SAS) to aid in stabilizing the helicopter inflight and in a hover. The simplest of these systems is aforce trim system, which uses a magnetic clutch andsprings to hold the cyclic control in the position whereit was released. More advanced systems use electricservos that actually move the flight controls. Theseservos receive control commands from a computer thatsenses helicopter attitude. Other inputs, such asheading, speed, altitude, and navigation informationmay be supplied to the computer to form a completeautopilot system. The SAS may be overridden ordisconnected by the pilot at any time.
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发表于 2009-3-20 23:49:36
Stability augmentation systems reduce pilot workloadby improving basic aircraft control harmony anddecreasing disturbances. These systems are very usefulwhen you are required to perform other duties, such assling loading and search and rescue operations.AUTOPILOTHelicopter autopilot systems are similar to stabilityaugmentations systems except they have additionalfeatures. An autopilot can actually fly the helicopterand perform certain functions selected by the pilot.These functions depend on the type of autopilot andsystems installed in the helicopter.The most common functions are altitude and headinghold. Some more advanced systems include a verticalspeed or indicated airspeed (IAS) hold mode, where aconstant rate of climb/descent or indicated airspeed ismaintained by the autopilot. Some autopilots have nav-VOR—Ground-based navigation system consisting of very high frequency omnidirectional range (VOR) stations which provide courseguidance.ILS (Instrument Landing System)—A precision instrument approachsystem, which normally consists of the following electronic componentsand visual aids: localizer, glide slope, outer marker, and approachlights.GPS (Global Positioning System)—A satellite-based radio positioning,navigation, and time-transfer system.IFR (Instrument Flight Rules)—Rules that govern the procedure forconducting flight in weather conditions below VFR weather minimums.The term IFR also is used to define weather conditions and the type offlight plan under which an aircraft is operating.5-11depends on the temperature of the outside air. Air conditioning provides better cooling but it is more complex and weighs more than a ram air system.Piston powered helicopters use a heat exchangershroud around the exhaust manifold to provide cabinheat. Outside air is piped to the shroud and the hotexhaust manifold heats the air, which is then blowninto the cockpit. This warm air is heated by the exhaustmanifold but is not exhaust gas. Turbine helicoptersuse a bleed air system for heat. Bleed air is hot, compressed, discharge air from the engine compressor. Hotair is ducted from the compressor to the helicoptercabin through a pilot-controlled, bleed air valve.ANTI-ICING SYSTEMSMost anti-icing equipment installed on small helicoptersis limited to engine intake anti-ice and pitot heat systems.The anti-icing system found on most turbine-poweredhelicopters uses engine bleed air. The bleed air flowsthrough the inlet guide vanes to prevent ice formation onthe hollow vanes. A pilot-controlled, electrically operatedvalve on the compressor controls the air flow. The pitotheat system uses an electrical element to heat the pitottube, thus melting or preventing ice formation.Airframe and rotor anti-icing may be found on somelarger helicopters, but it is not common due to thecomplexity, expense, and weight of such systems. Theleading edges of rotors may be heated with bleed air or
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发表于 2009-3-20 23:49:52
electrical elements to prevent ice formation. Balance andcontrol problems might arise if ice is allowed to formunevenly on the blades. Research is being done onlightweight ice-phobic (anti-icing) materials or coatings.These materials placed in strategic areas could significantly reduce ice formation and improve performance.5-126-1Title 14 of the Code of Federal Regulations (14 CFR)part 91 requires that pilots comply with the operatinglimitations specified in approved rotorcraft flight manuals, markings, and placards. Originally, flight manualswere often characterized by a lack of essential information and followed whatever format and content themanufacturer felt was appropriate. This changed withthe acceptance of the General Aviation ManufacturersAssociation’s (GAMA) Specification for Pilot’sOperating Handbook, which established a standardizedformat for all general aviation airplane and rotorcraftflight manuals. The term “Pilot’s Operating Handbook(POH)” is often used in place of “Rotorcraft FlightManual (RFM).” However, if “Pilot’s OperatingHandbook” is used as the main title instead of “RotorcraftFlight Manual,” a statement must be included on the titlepage indicating that the document is the FAA-ApprovedRotorcraft Flight Manual. Besides the preliminary pages, an FAA-ApprovedRotorcraft Flight Manual may contain as many as ten sections. These sections are: General Information; OperatingLimitations; Emergency Procedures; Normal Procedures;Performance; Weight and Balance; Aircraft and SystemsDescription; Handling, Servicing, and Maintenance; andSupplements. Manufacturers have the option of includinga tenth section on Safety and Operational Tips and analphabetical index at the end of the handbook.PRELIMINARY PAGESWhile rotorcraft flight manuals may appear similar forthe same make and model of aircraft, each flight man-ual is unique since it contains specific informationabout a particular aircraft, such as the equipmentinstalled, and weight and balance information.Therefore, manufacturers are required to include theserial number and registration on the title page to identify the aircraft to which the flight manual belongs. If aflight manual does not indicate a specific aircraft registration and serial number, it is limited to general studypurposes only.Most manufacturers include a table of contents, whichidentifies the order of the entire manual by section number and title. Usually, each section also contains its owntable of contents. Page numbers reflect the section youare reading, 1-1, 2-1, 3-1, and so on. If the flight manualis published in looseleaf form, each section is usually
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marked with a divider tab indicating the section numberor title, or both. The Emergency Procedures section mayhave a red tab for quick identification and reference.GENERAL INFORMATIONThe General Information section provides the basicdescriptive information on the rotorcraft and the powerplant. In some manuals there is a three-view drawing ofthe rotorcraft that provides the dimensions of variouscomponents, including the overall length and width, andthe diameter of the rotor systems. This is a good place toquickly familiarize yourself with the aircraft.You can find definitions, abbreviations, explanations ofsymbology, and some of the terminology used in themanual at the end of this section. At the option of themanufacturer, metric and other conversion tables mayalso be included.OPERATING LIMITATIONSThe Operating Limitations section contains only thoselimitations required by regulation or that are necessaryfor the safe operation of the rotorcraft, powerplant, systems, and equipment. It includes operating limitations,instrument markings, color coding, and basic placards.Some of the areas included are: airspeed, altitude, rotor,and powerplant limitations, including fuel and oilrequirements; weight and loading distribution; andflight limitations.AIRSPEED LIMITATIONSAirspeed limitations are shown on the airspeed indicator by color coding and on placards or graphs in theFigure 6-1. The Rotorcraft Flight Manual is a regulatory document in terms of the maneuvers, procedures, and operatinglimitations described therein.6-2aircraft. A red line on the airspeed indicator shows theairspeed limit beyond which structural damage couldoccur. This is called the never exceed speed, or VNE.The normal operating speed range is depicted by a greenarc. A blue line is sometimes added to show the maximum safe autorotation speed. ALTITUDE LIMITATIONSIf the rotorcraft has a maximum operating density altitude, it is indicated in this section of the flight manual.Sometimes the maximum altitude varies based on different gross weights.ROTOR LIMITATIONSLow rotor r.p.m. does not produce sufficient lift, andhigh r.p.m. may cause structural damage, thereforerotor r.p.m. limitations have minimum and maximumvalues. A green arc depicts the normal operating rangewith red lines showing the minimum and maximumlimits. There are two different rotor r.p.m. limitations: power-onand power-off. Power-on limitations apply anytime theengine is turning the rotor and is depicted by a fairly narrow green band. A yellow arc may be included to show a
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发表于 2009-3-20 23:50:18
transition range, which means that operation within thisrange is limited. Power-off limitations apply anytime theengine is not turning the rotor, such as when in an autorotation. In this case, the green arc is wider than the poweron arc, indicating a larger operating range.POWERPLANT LIMITATIONSThe Powerplant Limitations area describes operatinglimitations on the rotorcraft’s engine including suchitems as r.p.m. range, power limitations, operating temperatures, and fuel and oil requirements. Most turbineengines and some reciprocating engines have a maximum power and a maximum continuous power rating.The “maximum power” rating is the maximum powerthe engine can generate and is usually limited by time.The maximum power range is depicted by a yellow arcon the engine power instruments, with a red line indicating the maximum power that must not be exceeded.“Maximum continuous power” is the maximum powerthe engine can generate continually, and is depicted bya green arc. Like on a torque and turbine outlet temperature gauge,the red line on a manifold pressure gauge indicates themaximum amount of power. A yellow arc on the gaugewarns of pressures approaching the limit of ratedpower. A placard near the gauge lists the maximumreadings for specific conditions. WEIGHT AND LOADING DISTRIBUTIONThe Weight and Loading Distribution area contains themaximum certificated weights, as well as the center ofgravity (CG) range. The location of the reference datumused in balance computations should also be included inthis section. Weight and balance computations are notprovided here, but rather in the Weight and BalanceSection of the FAA-Approved Rotocraft Flight Manual.150 20406080100120AIRSPEEDKNOTS171412864MPHX 10Figure 6-2. Typical airspeed indicator limitations and markings.ROTORENGINERPM1005l0l23
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45l52025303540Figure 6-3. Markings on a typical dual-needle tachometer in areciprocating-engine helicopter. The outer band shows thelimits of the superimposed needles when the engine is turning the rotor. The inner band indicates the power-off limits.405060 7080901001101200102030TORQUEPERCENT123456789TURBOUTTEMP°C X 100Figure 6-4. Torque and turbine outlet temperature (TOT)gauges are commonly used with turbine-powered aircraft.6-3FLIGHT LIMITATIONSThis area lists any maneuvers which are prohibited,such as acrobatic flight or flight into known icing conditions. If the rotorcraft can only be flown in VFRconditions, it will be noted in this area. Also includedare the minimum crew requirements, and the pilot seatlocation, if applicable, where solo flights must be conducted.PLACARDSAll rotorcraft generally have one or more placards displayed that have a direct and important bearing on thesafe operation of the rotorcraft. These placards arelocated in a conspicuous place within the cabin andnormally appear in the Limitations Section. Since VNEchanges with altitude, this placard can be found in allhelicopters. EMERGENCY PROCEDURESConcise checklists describing the recommended procedures and airspeeds for coping with various types ofemergencies or critical situations can be found in thissection. Some of the emergencies covered include:engine failure in a hover and at altitude, tail rotor failures, fires, and systems failures. The procedures forrestarting an engine and for ditching in the water mightalso be included.Manufacturers may first show the emergencies checklists in an abbreviated form with the order of
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itemsreflecting the sequence of action. This is followed byamplified checklists providing additional informationto help you understand the procedure. To be preparedfor an abnormal or emergency situation, memorize thefirst steps of each checklist, if not all the steps. If timepermits, you can then refer to the checklist to make sureall items have been covered. (For more information onemergencies, refer to Chapter 11—Helicopter Emergenciesand Chapter 21—Gyroplane Emergencies.)Manufacturers also are encouraged to include an optionalarea titled “Abnormal Procedures,” which describes recommended procedures for handling malfunctions that arenot considered to be emergencies. This informationwould most likely be found in larger helicopters.NORMAL PROCEDURESThe Normal Procedures is the section you will probably use the most. It usually begins with a listing of theairspeeds, which may enhance the safety of normaloperations. It is a good idea to memorize the airspeedsthat are used for normal flight operations. The next partof the section includes several checklists, which takeyou through the preflight inspection, before startingprocedure, how to start the engine, rotor engagement,ground checks, takeoff, approach, landing, and shutdown. Some manufacturers also include the proceduresfor practice autorotations. To avoid skipping an important step, you should always use a checklist when one isavailable. (More information on maneuvers can befound in Chapter 9—Basic Maneuvers, Chapter 10—Advanced Maneuvers, and Chapter 20—GyroplaneFlight Operations.)PERFORMANCEThe Performance Section contains all the informationrequired by the regulations, and any additional performance information the manufacturer feels mayenhance your ability to safely operate the rotorcraft.l5l0202535 530MANIFOLDPRESSUREINCHESOF MERCURYFigure 6-5. A manifold pressure gauge is commonly usedwith piston-powered aircraft.Press Alt.1,000 FTF OAT 8 4 6 8 10 12 140 109 109 105 84 61 -- --109 109 109 109 98 77 58
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