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you will encounter a problem called “fixation.” This resultsfrom a natural human inclination to observe a specificinstrument carefully and accurately, often to the exclusionof other instruments. Fixation on a single instrument usually results in poor control. For example, while performinga turn, you may have a tendency to watch only the turn-andslip indicator instead of including other instruments in yourcross-check. This fixation on the turn-and-slip indicatoroften leads to a loss of altitude through poor pitch and bankcontrol. You should look at each instrument only longenough to understand the information it presents, then continue on to the next one. Similarly, you may find yourselfplacing too much “emphasis” on a single instrument,instead of relying on a combination of instruments nec-essary for helicopter performance information. This differs from fixation in that you are using other instruments,but are giving too much attention to a particular one.During performance of a maneuver, you may sometimesfail to anticipate significant instrument indications following attitude changes. For example, during levelofffrom a climb or descent, you may concentrate on pitchcontrol, while forgetting about heading or roll information. This error, called “omission,” results in erraticcontrol of heading and bank.In spite of these common errors, most pilots can adaptwell to flight by instrument reference after instructionand practice. You may find that you can control the helicopter more easily and precisely by instruments.INSTRUMENT INTERPRETATIONThe flight instruments together give a picture of whatis going on. No one instrument is more important thanthe next; however, during certain maneuvers or conditions, those instruments that provide the most pertinentand useful information are termed primary instruments.Those which back up and supplement the primaryinstruments are termed supporting instruments. Forexample, since the attitude indicator is the only instrument that provides instant and direct aircraft attitudeinformation, it should be considered primary duringany change in pitch or bank attitude. After the new attitude is established, other instruments become primary,and the attitude indicator usually becomes the supporting instrument.Figure 12-10. In most situations, the cross-check pattern includes the attitude indicator between the cross-check of each of theother instruments. A typical cross-check might progress as follows: attitude indicator, altimeter, attitude indicator, VSI, attitudeindicator, heading indicator, attitude indicator, and so on.12-7AIRCRAFT CONTROLControlling the helicopter is the result of accuratelyinterpreting the flight instruments and translating thesereadings into correct control responses. Aircraft controlinvolves adjustment to pitch, bank, power, and trim inorder to achieve a desired flight path.Pitch attitude control is controlling the movement ofthe helicopter about its lateral axis. After interpretingthe helicopter’s pitch attitude by reference to the pitchinstruments (attitude indicator, altimeter, airspeed indicator, and vertical speed indicator), cyclic controladjustments are made to affect the desired pitch attitude. In this chapter, the pitch attitudes illustrated areapproximate and will vary with different helicopters.Bank attitude control is controlling the angle made bythe lateral tilt of the rotor and the natural horizon, or,the movement of the helicopter about its longitudinalaxis. After interpreting the helicopter’s bank instruments (attitude indicator, heading indicator, and turnindicator), cyclic control adjustments are made to attainthe desired bank attitude.Power control is the application of collective pitch withcorresponding throttle control, where applicable. Instraight-and-level flight, changes of collective pitch aremade to correct for altitude deviations if the error ismore than 100 feet, or the airspeed is off by more than10 knots. If the error is less than that amount, use aslight cyclic climb or descent.In order to fly a helicopter by reference to theinstruments, you should know the approximatepower settings required for your particular helicopterin various load configurations and flight conditions.Trim, in helicopters, refers to the use of the cyclic centering button, if the helicopter is so equipped, to relieve allpossible cyclic pressures. Trim also refers to the use ofpedal adjustment to center the ball of the turn indicator.Pedal trim is required during all power changes.The proper adjustment of collective pitch and cyclicfriction helps you relax during instrument flight.Friction should be adjusted to minimize overcontrolling and to prevent creeping, but not applied to such adegree that control movement is limited. In addition,many helicopters equipped for instrument flight contain stability augmentation systems or an autopilot tohelp relieve pilot workload.STRAIGHT-AND-LEVEL FLIGHTStraight-and-level unaccelerated flight consists ofmaintaining the desired altitude, heading, airspeed, andpedal trim.PITCH CONTROLThe pitch attitude of a helicopter is the angular relationof its longitudinal axis and the natural horizon. If available, the attitude indicator is used to establish thedesired pitch attitude. In level flight, pitch attitudevaries with airspeed and center of gravity. At a constantaltitude and a stabilized airspeed, the pitch attitude isapproximately level. PITCH CONTR CONTROL OLPITCH CONTROLFigure 12-11. The flight instruments for pitch control are the airspeed indicator, attitude indicator, altimeter, and verticalspeed indicator.12-8
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ATTITUDE INDICATORThe attitude indicator gives a direct indication of thepitch attitude of the helicopter. In visual flight, youattain the desired pitch attitude by using the cyclic toraise and lower the nose of the helicopter in relation tothe natural horizon. During instrument flight, you follow exactly the same procedure in raising or loweringthe miniature aircraft in relation to the horizon bar.You may note some delay between control applicationand resultant instrument change. This is the normalcontrol lag in the helicopter and should not be confusedwith instrument lag. The attitude indicator may showsmall misrepresentations of pitch attitude duringmaneuvers involving acceleration, deceleration, orturns. This precession error can be detected quickly bycross-checking the other pitch instruments.If the miniature aircraft is properly adjusted on theground, it may not require readjustment in flight. If theminiature aircraft is not on the horizon bar after leveloff at normal cruising airspeed, adjust it as necessarywhile maintaining level flight with the other pitchinstruments. Once the miniature aircraft has beenadjusted in level flight at normal cruising airspeed,leave it unchanged so it will give an accurate picture ofpitch attitude at all times.When making initial pitch attitude corrections to maintain altitude, the changes of attitude should be smalland smoothly applied. The initial movement of thehorizon bar should not exceed one bar width high orlow. If a further change is required, anadditional correction of one-half bar normally correctsany deviation from the desired altitude. This one andone-half bar correction is normally the maximum pitchattitude correction from level flight attitude. After youhave made the correction, cross-check the other pitchinstruments to determine whether the pitch attitudechange is sufficient. If more correction is needed toreturn to altitude, or if the airspeed varies more than 10knots from that desired, adjust the power.ALTIMETERThe altimeter gives an indirect indication of the pitchattitude of the helicopter in straight-and-level flight.Since the altitude should remain constant in levelflight, deviation from the desired altitude shows a needfor a change in pitch attitude, and if necessary, power.When losing altitude, raise the pitch attitude and, ifnecessary, add power. When gaining altitude, lower thepitch attitude and, if necessary, reduce power.The rate at which the altimeter moves helps in determining pitch attitude. A very slow movement of thealtimeter indicates a small deviation from the desiredpitch attitude, while a fast movement of the altimeterindicates a large deviation from the desired pitch attitude. Make any corrective action promptly, with smallcontrol changes. Also, remember that movement of thealtimeter should always be corrected by two distinctchanges. The first is a change of attitude to stop thealtimeter; and the second, a change of attitude toreturn smoothly to the desired altitude. If the altitudeand airspeed are more than 100 feet and 10 knots low,respectively, apply power along with an increase ofpitch attitude. If the altitude and airspeed are high bymore than 100 feet and 10 knots, reduce power andlower the pitch attitude.There is a small lag in the movement of the altimeter;however, for all practical purposes, consider that thealtimeter gives an immediate indication of a change, ora need for change in pitch attitude.Since the altimeter provides the most pertinent information regarding pitch in level flight, it is consideredprimary for pitch.VERTICAL SPEED INDICATORThe vertical speed indicator gives an indirect indicationof the pitch attitude of the helicopter and should be usedin conjunction with the other pitch instruments to attaina high degree of accuracy and precision. The instrumentindicates zero when in level flight. Any movement ofthe needle from the zero position shows a need for animmediate change in pitch attitude to return it to zero.Always use the vertical speed indicator in conjunctionwith the altimeter in level flight. If a movement of thevertical speed indicator is detected, immediately use theproper corrective measures to return it to zero. If thecorrection is made promptly, there is usually little or nochange in altitude. If you do not zero the needle of theFigure 12-12. The initial pitch correction at normal cruise isone bar width.12-9vertical speed indicator immediately, the results willshow on the altimeter as a gain or loss of altitude.The initial movement of the vertical speed needle isinstantaneous and indicates the trend of the verticalmovement of the helicopter. It must be realized thata period of time is necessary for the vertical speedindicator to reach its maximum point of deflectionafter a correction has been made. This time elementis commonly referred to as “lag.” The lag is directlyproportional to the speed and magnitude of the pitchchange. If you employ smooth control techniquesand make small adjustments in pitch attitude, lag isminimized, and the vertical speed indicator is easyto interpret. Overcontrolling can be minimized byfirst neutralizing the controls and allowing the pitchattitude to stabilize; then readjusting the pitch attitude by noting the indications of the other pitchinstruments.Occasionally, the vertical speed indicator may beslightly out of calibration. This could result in the
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instrument indicating a slight climb or descent evenwhen the helicopter is in level flight. If it cannot bereadjusted properly, this error must be taken into consideration when using the vertical speed indicator forpitch control. For example, if the vertical speed indicator showed a descent of 100 f.p.m. when the helicopterwas in level flight, you would have to use that indication as level flight. Any deviation from that readingwould indicate a change in attitude.AIRSPEED INDICATORThe airspeed indicator gives an indirect indication ofhelicopter pitch attitude. With a given power settingand pitch attitude, the airspeed remains constant. If theairspeed increases, the nose is too low and should beraised. If the airspeed decreases, the nose is too highand should be lowered. A rapid change in airspeed indicates a large change in pitch attitude, and a slow changein airspeed indicates a small change in pitch attitude.There is very little lag in the indications of the airspeedindicator. If, while making attitude changes, you noticesome lag between control application and change ofairspeed, it is most likely due to cyclic control lag.Generally, a departure from the desired airspeed, due toan inadvertent pitch attitude change, also results in achange in altitude. For example, an increase in airspeeddue to a low pitch attitude results in a decrease in altitude. A correction in the pitch attitude regains both airspeed and altitude.BANK CONTROLThe bank attitude of a helicopter is the angular relationof its lateral axis and the natural horizon. To maintain astraight course in visual flight, you must keep thelateral axis of the helicopter level with the natural horizon. Assuming the helicopter is in coordinated flight,any deviation from a laterally level attitude produces aturn. ATTITUDE INDICATORThe attitude indicator gives a direct indication of thebank attitude of the helicopter. For instrument flight,BANK CONTR CONTROL OLBANK CONTROLFigure 12-13. The flight instruments used for bank control are the attitude, heading, and turn indicators.12-10the miniature aircraft and the horizon bar of the attitudeindicator are substituted for the actual helicopter andthe natural horizon. Any change in bank attitude of thehelicopter is indicated instantly by the miniature aircraft. For proper interpretations of this instrument, youshould imagine being in the miniature aircraft. If thehelicopter is properly trimmed and the rotor tilts, a turnbegins. The turn can be stopped by leveling the miniatureaircraft with the horizon bar. The ball in the turn-and-slipindicator should always be kept centered through properpedal trim.The angle of bank is indicated by the pointer on thebanking scale at the top of the instrument. 14] Small bank angles, which may not be seen byobserving the miniature aircraft, can easily be determined by referring to the banking scale pointer.Pitch and bank attitudes can be determined simultaneously on the attitude indicator. Even though the miniatureaircraft is not level with the horizon bar, pitch attitude canbe established by observing the relative position of theminiature aircraft and the horizon bar.The attitude indicator may show small misrepresentations of bank attitude during maneuvers that involveturns. This precession error can be immediatelydetected by closely cross-checking the other bankinstruments during these maneuvers. Precession normally is noticed when rolling out of a turn. If, on thecompletion of a turn, the miniature aircraft is level andthe helicopter is still turning, make a small change ofbank attitude to center the turn needle and stop themovement of the heading indicator.HEADING INDICATORIn coordinated flight, the heading indicator gives anindirect indication of the helicopter’s bank attitude.When a helicopter is banked, it turns. When the lateralaxis of the helicopter is level, it flies straight.Therefore, in coordinated flight, when the heading indicator shows a constant heading, the helicopter is levellaterally. A deviation from the desired heading indicates a bank in the direction the helicopter is turning.A small angle of bank is indicated by a slow change ofheading; a large angle of bank is indicated by a rapidchange of heading. If a turn is noticed, apply oppositecyclic until the heading indicator indicates the desiredheading, simultaneously checking that the ball is centered. When making the correction to the desired heading, you should not use a bank angle greater than thatrequired to achieve a standard rate turn. In addition, ifthe number of degrees of change is small, limit thebank angle to the number of degrees to be turned. Bankangles greater than these require more skill and precision in attaining the desired results. During straightand-level flight, the heading indicator is the primaryreference for bank control.TURN INDICATORDuring coordinated flight, the needle of the turn-andslip indicator gives an indirect indication of the bankattitude of the helicopter. When the needle is displaced from the vertical position, the helicopter isturning in the direction of the displacement. Thus, ifthe needle is displaced to the left, the helicopter isturning left. Bringing the needle back to the verticalposition with the cyclic produces straight flight. Aclose observation of the needle is necessary to accurately interpret small deviations from the desiredposition.Cross-check the ball of the turn-and-slip indicator todetermine that the helicopter is in coordinated flight. Ifthe rotor is laterally level and torque is properly compensated for by pedal pressure, the ball remains in the
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center. To center the ball, level the helicopter laterallyby reference to the other bank instruments, then centerthe ball with pedal trim. Torque correction pressuresvary as you make power changes. Always check theball following such changes.COMMON ERRORS DURING STRAIGHT-AND-LEVEL FLIGHT1. Failure to maintain altitude.2. Failure to maintain heading.3. Overcontrolling pitch and bank during corrections.4. Failure to maintain proper pedal trim.5. Failure to cross-check all available instruments.30°0°60°90°Figure 12-14. The banking scale at the top of the attitude indicator indicates varying degrees of bank. In this example, thehelicopter is banked a little over 10° to the right.12-11POWER CONTROL DURING STRAIGHT-AND-LEVEL FLIGHTEstablishing specific power settings is accomplishedthrough collective pitch adjustments and throttlecontrol, where necessary. For reciprocating poweredhelicopters, power indications are observed on themanifold pressure gauge. For turbine powered helicopters, power is observed on the torque gauge. (Since mostIFR certified helicopters are turbine powered, thisdiscussion concentrates on this type of helicopter.)At any given airspeed, a specific power setting determines whether the helicopter is in level flight, in aclimb, or in a descent. For example, cruising airspeedmaintained with cruising power results in level flight.If you increase the power setting and hold the airspeedconstant, the helicopter climbs. Conversely, if youdecrease power and hold the airspeed constant, the helicopter descends. As a rule of thumb, in a turbine-enginepowered helicopter, a 10 to 15 percent change in thetorque value required to maintain level flight results in aclimb or descent of approximately 500 f.p.m., if the airspeed remains the same.If the altitude is held constant, power determines theairspeed. For example, at a constant altitude, cruisingpower results in cruising airspeed. Any deviation fromthe cruising power setting results in a change of airspeed. When power is added to increase airspeed, thenose of the helicopter pitches up and yaws to the rightin a helicopter with a counterclockwise main rotorblade rotation. When power is reduced to decrease airspeed, the nose pitches down and yaws to the left. Theyawing effect is most pronounced in single-rotor helicopters, and is absent in helicopters with counter-rotatingrotors. To counteract the yawing tendency of the helicopter, apply pedal trim during power changes.To maintain a constant altitude and airspeed in levelflight, coordinate pitch attitude and power control. Therelationship between altitude and airspeed determinesthe need for a change in power and/or pitch attitude. Ifthe altitude is constant and the airspeed is high or low,change the power to obtain the desired airspeed.During the change in power, make an accurate interpretation of the altimeter; then counteract any deviation from the desired altitude by an appropriate changeof pitch attitude. If the altitude is low and the airspeedis high, or vice versa, a change in pitch attitude alonemay return the helicopter to the proper altitude and airspeed. If both airspeed and altitude are low, or if bothare high, a change in both power and pitch attitude isnecessary.To make power control easy when changing airspeed, itis necessary to know the approximate power settings forthe various airspeeds that will be flown. When the air-speed is to be changed any appreciable amount, adjustthe torque so that it is approximately five percent over orunder that setting necessary to maintain the new airspeed.As the power approaches the desired setting, include thetorque meter in the cross-check to determine when theproper adjustment has been accomplished. As the airspeed is changing, adjust the pitch attitude to maintain aconstant altitude. A constant heading should be maintained throughout the change. As the desired airspeed isapproached, adjust power to the new cruising power setting and further adjust pitch attitude to maintain altitude.Overpowering and underpowering torque approximatelyfive percent results in a change of airspeed at a moderaterate, which allows ample time to adjust pitch and banksmoothly. The instrument indications for straight-andlevel flight at normal cruise, and during the transitionfrom normal cruise to slow cruise are illustrated in figures 12-15 and 12-16 on the next page. After the airspeedhas stabilized at slow cruise, the attitude indicator showsan approximate level pitch attitude.The altimeter is the primary pitch instrument duringlevel flight, whether flying at a constant airspeed, orduring a change in airspeed. Altitude should not changeduring airspeed transitions. The heading indicatorremains the primary bank instrument. Whenever theairspeed is changed any appreciable amount, the torquemeter is momentarily the primary instrument for powercontrol. When the airspeed approaches that desired, theairspeed indicator again becomes the primary instrument for power control.The cross-check of the pitch and bank instruments toproduce straight-and-level flight should be combinedwith the power control instruments. With a constantpower setting, a normal cross-check should besatisfactory. When changing power, the speed of thecross-check must be increased to cover the pitch andbank instruments adequately. This is necessary tocounteract any deviations immediately.COMMON ERRORS DURING AIRSPEED CHANGES1. Improper use of power.2. Overcontrolling pitch attitude.
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3. Failure to maintain heading.4. Failure to maintain altitude.5. Improper pedal trim.STRAIGHT CLIMBS (CONSTANT AIRSPEEDAND CONSTANT RATE)For any power setting and load condition, there is onlyone airspeed that will give the most efficient rate ofclimb. To determine this, you should consult the climbdata for the type of helicopter being flown. The technique varies according to the airspeed on entry andwhether you want to make a constant airspeed or constant rate climb.12-12ENTRYTo enter a constant airspeed climb from cruise airspeed,when the climb speed is lower than cruise speed, simultaneously increase power to the climb power settingand adjust pitch attitude to the approximate climb attitude. The increase in power causes the helicopter tostart climbing and only very slight back cyclic pressureis needed to complete the change from level to climbattitude. The attitude indicator should be used toaccomplish the pitch change. If the transition fromlevel flight to a climb is smooth, the vertical speed indicator shows an immediate upward trend and then stopsat a rate appropriate to the stabilized airspeed and attitude. Primary and supporting instruments for climbentry are illustrated in figure 12-17.When the helicopter stabilizes on a constant airspeedand attitude, the airspeed indicator becomes primaryFigure 12-16. Flight instrument indications in straight-and-level flight with airspeed decreasing.Figure 12-15. Flight instrument indications in straight-and-level flight at normal cruise speed.405060 7080901001101200102030TORQUEPERCENTSupporting Pitchand BankPrimary Power Primary PitchSupporting Pitch Primary Bank Supporting BankSupportingPower405060 7080901001101200102030TORQUEPERCENTPrimary BankPrimaryPowerInitiallyPrimary Pitch Supporting Pitchand BankPrimary Power as AirspeedApproaches Desired ValueSupporting Pitch Supporting Bank12-13for pitch. The torque meter continues to be primary forpower and should be monitored closely to determine ifthe proper climb power setting is being maintained.Primary and supporting instruments for a stabilizedconstant airspeed climb are shown in figure 12-18.The technique and procedures for entering a constantrate climb are very similar to those previouslydescribed for a constant airspeed climb. For trainingpurposes, a constant rate climb is entered from climbairspeed. The rate used is the one that is appropriate for405060 7080901001101200102030TORQUEPERCENTPrimary PitchSupporting BankPrimaryPowerSupporting Pitch Primary Bank Supporting BankFigure 12-17. Flight instrument indications during climb entry for a constant airspeed climb.405060 7080901001101200102030TORQUEPERCENTPrimary Pitch Supporting Pitchand BankPrimaryPowerSupporting Pitch Primary Bank Supporting BankFigure 12-18. Flight instrument indications in a stabilized, constant airspeed climb.12-14the particular helicopter being flown. Normally, in helicopters with low climb rates, 500 f.p.m. is appropriate,in helicopters capable of high climb rates, use a rate of1,000 f.p.m.To enter a constant rate climb, increase power to theapproximate setting for the desired rate. As power isapplied, the airspeed indicator is primary for pitch untilthe vertical speed approaches the desired rate. At thistime, the vertical speed indicator becomes primary forpitch. Change pitch attitude by reference to the attitudeindicator to maintain the desired vertical speed. Whenthe VSI becomes primary for pitch, the airspeed indicator becomes primary for power. Primary and supportinginstruments for a stabilized constant rate climb are illustrated in figure 12-19. Adjust power to maintain desired
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airspeed. Pitch attitude and power corrections should beclosely coordinated. To illustrate this, if the verticalspeed is correct but the airspeed is low, add power. Aspower is increased, it may be necessary to lower thepitch attitude slightly to avoid increasing the verticalrate. Adjust the pitch attitude smoothly to avoid overcontrolling. Small power corrections usually will besufficient to bring the airspeed back to the desired indication.LEVELOFFThe leveloff from a constant airspeed climb must bestarted before reaching the desired altitude. Although theamount of lead varies with the helicopter being flownand your piloting technique, the most important factor isvertical speed. As a rule of thumb, use 10 percent of thevertical velocity as your lead point. For example, if therate of climb is 500 f.p.m., initiate the leveloff approximately 50 feet before the desired altitude. When theproper lead altitude is reached, the altimeter becomesprimary for pitch. Adjust the pitch attitude to the levelflight attitude for that airspeed. Cross-check the altimeter and VSI to determine when level flight has beenattained at the desired altitude. To level off at cruise airspeed, if this speed is higher than climb airspeed, leavethe power at the climb power setting until the airspeedapproaches cruise airspeed, then reduce it to the cruisepower setting.The leveloff from a constant rate climb is accomplishedin the same manner as the leveloff from a constant airspeed climb.STRAIGHT DESCENTS (CONSTANTAIRSPEED AND CONSTANT RATE)A descent may be performed at any normal airspeed thehelicopter is capable of, but the airspeed must be determined prior to entry. The technique is determined bywhether you want to perform a constant airspeed or aconstant rate descent.ENTRYIf your airspeed is higher than descending airspeed, andyou wish to make a constant airspeed descent at thedescending airspeed, reduce power to the descendingpower setting and maintain a constant altitude usingcyclic pitch control. When you approach the descending airspeed, the airspeed indicator becomes primaryfor pitch, and the torque meter is primary for power. Asyou hold the airspeed constant, the helicopter begins todescend. For a constant rate descent, reduce the power405060 7080901001101200102030TORQUEPERCENTSupportingPowerSupporting Pitchand BankPrimary BankPrimary PowerPrimary Pitch Supporting BankFigure 12-19. Flight instrument indications in a stabilized constant rate climb.12-15to the approximate setting for the desired rate. If thedescent is started at the descending airspeed, the airspeed indicator is primary for pitch until the VSIapproaches the desired rate. At this time, the verticalspeed indicator becomes primary for pitch, and theairspeed indicator becomes primary for power.Coordinate power and pitch attitude control as wasdescribed earlier for constant rate climbs.LEVELOFFThe leveloff from a constant airspeed descent may bemade at descending airspeed or at cruise airspeed, ifthis is higher than descending airspeed. As in a climbleveloff, the amount of lead depends on the rate ofdescent and control technique. For a leveloff atdescending airspeed, the lead should be approximately10 percent of the vertical speed. At the lead altitude,simultaneously increase power to the setting necessaryto maintain descending airspeed in level flight. At thispoint, the altimeter becomes primary for pitch, and theairspeed indicator becomes primary for power.To level off at a higher airspeed than descending airspeed, increase the power approximately 100 to 150 feetprior to reaching the desired altitude. The power settingshould be that which is necessary to maintain thedesired airspeed in level flight. Hold the vertical speedconstant until approximately 50 feet above the desiredaltitude. At this point, the altimeter becomes primaryfor pitch, and the airspeed indicator becomes primaryfor power. The leveloff from a constant rate descentshould be accomplished in the same manner as the leveloff from a constant airspeed descent.COMMON ERRORS DURING STRAIGHT CLIMBSAND DESCENTS1. Failure to maintain heading.2. Improper use of power.3. Poor control of pitch attitude.4. Failure to maintain proper pedal trim.5. Failure to level off on desired altitude.TURNSWhen making turns by reference to the flight instruments, they should be made at a definite rate. Turnsdescribed in this chapter are those that do not exceed astandard rate of 3° per second as indicated on the turnand-slip indicator. True airspeed determines the angleof bank necessary to maintain a standard rate turn. Arule of thumb to determine the approximate angle ofbank required for a standard rate turn is to divide yourairspeed by 10 and add one-half the result. For example, at 60 knots, approximately 9° of bank is required(60 ÷ 10 = 6 + 3 = 9); at 80 knots, approximately 12° of
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bank is needed for a standard rate turn.To enter a turn, apply lateral cyclic in the direction of thedesired turn. The entry should be accomplishedsmoothly, using the attitude indicator to establish theapproximate bank angle. When the turn indicator indicates a standard rate turn, it becomes primary for bank.The attitude indicator now becomes a supporting instrument. During level turns, the altimeter is primary forpitch, and the airspeed indicator is primary for power.Primary and supporting instruments for a stabilized standard rate turn are illustrated in figure 12-20. If anFigure 12-20. Flight instrument indications for a standard rate turn to the left.405060 7080901001101200102030TORQUEPERCENTPrimary Bank InitiallySupporting PitchPrimary Power Primary PitchSupporting Pitch Primary Bank asTurn is EstablishedSupportingPower12-16increase in power is required to maintain airspeed, slightforward cyclic pressure may be required since the helicopter tends to pitch up as collective pitch angle isincreased. Apply pedal trim, as required, to keep the ballcentered.To recover to straight-and-level flight, apply cyclic inthe direction opposite the turn. The rate of roll-outshould be the same as the rate used when rolling intothe turn. As you initiate the turn recover, the attitudeindicator becomes primary for bank. When the helicopter is approximately level, the heading indicatorbecomes primary for bank as in straight-and-levelflight. Cross-check the airspeed indicator and ballclosely to maintain the desired airspeed and pedal trim.TURNS TO A PREDETERMINED HEADINGA helicopter turns as long as its lateral axis is tilted; therefore, the recovery must start before the desired heading isreached. The amount of lead varies with the rate of turnand your piloting technique.As a guide, when making a 3° per second rate of turn,use a lead of one-half the bank angle. For example, ifyou are using a 12° bank angle, use half of that, or 6°,as the lead point prior to your desired heading. Use thislead until you are able to determine the exact amountrequired by your particular technique. The bank angleshould never exceed the number of degrees to beturned. As in any standard rate turn, the rate of recovery should be the same as the rate for entry. Duringturns to predetermined headings, cross-check the primary and supporting pitch, bank, and power instruments closely.TIMED TURNSA timed turn is a turn in which the clock and turn-andslip indicator are used to change heading a definitenumber of degrees in a given time. For example, usinga standard rate turn, a helicopter turns 45° in 15 seconds. Using a half-standard rate turn, the helicopterturns 45° in 30 seconds. Timed turns can be used ifyour heading indicator becomes inoperative.Prior to performing timed turns, the turn coordinatorshould be calibrated to determine the accuracy of itsindications. To do this, establish a standard rate turn byreferring to the turn-and-slip indicator. Then as thesweep second hand of the clock passes a cardinal point(12, 3, 6, or 9), check the heading on the heading indicator. While holding the indicated rate of turn constant,note the heading changes at 10-second intervals. If thehelicopter turns more or less than 30° in that interval, asmaller or larger deflection of the needle is necessaryto produce a standard rate turn. When you have calibrated the turn-and-slip indicator during turns in eachdirection, note the corrected deflections, if any, andapply them during all timed turns.You use the same cross-check and control technique inmaking timed turns that you use to make turns to a predetermined heading, except that you substitute theclock for the heading indicator. The needle of the turnand-slip indicator is primary for bank control, thealtimeter is primary for pitch control, and the airspeedindicator is primary for power control. Begin the roll-inwhen the clock’s second hand passes a cardinal point,hold the turn at the calibrated standard-rate indication,or half-standard-rate for small changes in heading, andbegin the roll-out when the computed number of seconds has elapsed. If the roll-in and roll-out rates are thesame, the time taken during entry and recovery neednot be considered in the time computation.If you practice timed turns with a full instrument panel,check the heading indicator for the accuracy of yourturns. If you execute the turns without the heading indicator, use the magnetic compass at the completion ofthe turn to check turn accuracy, taking compass deviation errors into consideration.CHANGE OF AIRSPEED IN TURNSChanging airspeed in turns is an effective maneuver forincreasing your proficiency in all three basic instrument skills. Since the maneuver involves simultaneouschanges in all components of control, proper executionrequires a rapid cross-check and interpretation, as wellas smooth control. Proficiency in the maneuver alsocontributes to your confidence in the instruments during attitude and power changes involved in more complex maneuvers.Pitch and power control techniques are the same asthose used during airspeed changes in straight-andlevel flight. As discussed previously, the angle of
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发表于 2009-3-21 00:06:34
banknecessary for a given rate of turn is proportional to thetrue airspeed. Since the turns are executed at standardrate, the angle of bank must be varied in direct proportion to the airspeed change in order to maintain aconstant rate of turn. During a reduction of airspeed,you must decrease the angle of bank and increase thepitch attitude to maintain altitude and a standard rateturn.The altimeter and the needle on the turn indicatorshould remain constant throughout the turn. Thealtimeter is primary for pitch control, and the turn needle is primary for bank control. The torque meter isprimary for power control while the airspeed is changing. As the airspeed approaches the new indication, theairspeed indicator becomes primary for power control.Two methods of changing airspeed in turns may beused. In the first method, airspeed is changed after theturn is established. In the second method, the airspeedchange is initiated simultaneously with the turn entry.The first method is easier, but regardless of the method12-17used, the rate of cross-check must be increased as youreduce power. As the helicopter decelerates, check thealtimeter and VSI for needed pitch changes, and thebank instruments for needed bank changes. If the needleof the turn-and-slip indicator shows a deviation fromthe desired deflection, change the bank. Adjust pitchattitude to maintain altitude. When the airspeedapproaches that desired, the airspeed indicator becomesprimary for power control. Adjust the torque meter tomaintain the desired airspeed. Use pedal trim to ensurethe maneuver is coordinated.Until your control technique is very smooth, frequentlycross-check the attitude indicator to keep from overcontrolling and to provide approximate bank anglesappropriate for the changing airspeeds.30° BANK TURNA turn using 30° of bank is seldom necessary, or advisable, in IMC, but it is an excellent maneuver to increaseyour ability to react quickly and smoothly to rapidchanges of attitude. Even though the entry and recovery technique are the same as for any other turn, youwill probably find it more difficult to control pitchbecause of the decrease in vertical lift as the bankincreases. Also, because of the decrease in vertical lift,there is a tendency to lose altitude and/or airspeed.Therefore, to maintain a constant altitude and airspeed,additional power is required. You should not initiate acorrection, however, until the instruments indicate theneed for a correction. During the maneuver, note theneed for a correction on the altimeter and vertical speedindicator, then check the indications on the attitudeindicator, and make the necessary adjustments. Afteryou have made this change, again check the altimeterand vertical speed indicator to determine whether ornot the correction was adequate.CLIMBING AND DESCENDING TURNSFor climbing and descending turns, the techniquesdescribed earlier for straight climbs and descents andthose for standard rate turns are combined. For practice,start the climb or descent and turn simultaneously. Theprimary and supporting instruments for a stabilized constant airspeed left climbing turn are illustrated in figure12-21. The leveloff from a climbing or descending turnis the same as the leveloff from a straight climb ordescent. To recover to straight-and-level flight, you maystop the turn and then level off, level off and then stopthe turn, or simultaneously level off and stop the turn.During climbing and descending turns, keep the ball ofthe turn indicator centered with pedal trim.COMPASS TURNSThe use of gyroscopic heading indicators make heading control very easy. However, if the heading indicator fails or your helicopter does not have one installed,you must use the magnetic compass for heading reference. When making compass-only turns, you need toadjust for the lead or lag created by acceleration anddeceleration errors so that you roll out on the desiredheading. When turning to a heading of north, the leadfor the roll-out must include the number of degrees ofyour latitude plus the lead you normally use in recovery from turns. During a turn to a south heading, maintain the turn until the compass passes south the number405060 7080901001101200102030TORQUEPERCENTPrimaryPowerSupporting Pitchand BankPrimary BankPrimary PitchSupporting PitchFigure 12-21. Flight instrument indications for a stabilized left climbing turn at a constant airspeed.12-18COMMON ERRORS DURINGUNUSUAL ATTITUDE RECOVERIES1. Failure to make proper pitch correction.2. Failure to make proper bank correction.3. Failure to make proper power correction.4. Overcontrol of pitch and/or bank attitude.5. Overcontrol of power.6. Excessive loss of altitude.EMERGENCIESEmergencies under instrument flight are handled similarly to those occurring during VFR flight. A thorough
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发表于 2009-3-21 00:06:49
knowledge of the helicopter and its systems, as well asgood aeronautical knowledge and judgment, preparesyou to better handle emergency situations. Safe operations begin with preflight planning and a thorough preflight. Plan your route of flight so that there are adequatelanding sites in the event you have to make an emergency landing. Make sure you have all your resources,such as maps, publications, flashlights, and fire extinguishers readily available for use in an emergency.During any emergency, you should first fly the aircraft.This means that you should make sure the helicopter isunder control, including the determination of emergencylanding sites. Then perform the emergency checklistmemory items, followed by written items in the RFM.Once all these items are under control, you should notifyATC. Declare any emergency on the last assigned ATCfrequency, or if one was not issued, transmit on the emergency frequency 121.5. Set the transponder to the emergency squawk code 7700. This code triggers an alarm ora special indicator in radar facilities.Most in-flight emergencies, including low fuel and acomplete electrical failure, require you to land as soonas possible. In the event of an electrical fire, turn all nonessential equipment off and land immediately. Someessential electrical instruments, such as the attitude indicator, may be required for a safe landing. A navigationradio failure may not require an immediate landing aslong as the flight can continue safely. In this case, youshould land as soon as practical. ATC may be able toprovide vectors to a safe landing area. For the specificdetails on what to do during an emergency, you shouldrefer to the RFM for the helicopter you are flying.of degrees of your latitude, minus your normal roll-outlead. For example, when turning from an easterlydirection to north, where the latitude is 30°, start theroll-out when the compass reads 037° (30° plus onehalf the 15° angle of bank, or whatever amount isappropriate for your rate of roll-out). When turningfrom an easterly direction to south, start the roll-outwhen the magnetic compass reads 203° (180° plus 30°minus one-half the angle of bank). When making similar turns from a westerly direction, the appropriatepoints at which to begin your roll-out would be 323°for a turn to north, and 157° for a turn to south.COMMON ERRORS DURING TURNS1. Failure to maintain desired turn rate.2. Failure to maintain altitude in level turns.3. Failure to maintain desired airspeed.4. Variation in the rate of entry and recovery.5. Failure to use proper lead in turns to a heading.6. Failure to properly compute time during timed turns.7. Failure to use proper leads and lags during thecompass turns.8. Improper use of power.9. Failure to use proper pedal trim.UNUSUAL ATTITUDESAny maneuver not required for normal helicopter instrument flight is an unusual attitude and may be caused byany one or a combination of factors, such as turbulence,disorientation, instrument failure, confusion, preoccupation with cockpit duties, carelessness in cross-checking,errors in instrument interpretation, or lack of proficiencyin aircraft control. Due to the instability characteristicsof the helicopter, unusual attitudes can be extremely critical. As soon as you detect an unusual attitude, make arecovery to straight-and-level flight as soon as possiblewith a minimum loss of altitude.To recover from an unusual attitude, correct bank andpitch attitude, and adjust power as necessary. All components are changed almost simultaneously, with littlelead of one over the other. You must be able to performthis task with and without the attitude indicator. If thehelicopter is in a climbing or descending turn, correctbank, pitch, and power. The bank attitude should becorrected by referring to the turn-and-slip indicator andattitude indicator. Pitch attitude should be corrected byreference to the altimeter, airspeed indicator, VSI, andattitude indicator. Adjust power by referring to the airspeed indicator and torque meter.Since the displacement of the controls used in recoveries from unusual attitudes may be greater than those fornormal flight, take care in making adjustments asstraight-and-level flight is approached. Cross-check theother instruments closely to avoid overcontrolling.Land as soon as possible—Land without delay at the nearest suitablearea, such as an open field, at which a safe approach and landing isassured.Land immediately—The urgency of the landing is paramount. The primary consideration is to assure the survival of the occupants. Landing intrees, water, or other unsafe areas should be considered only as a lastresort.Land as soon as practical—The landing site and duration of flight areat the discretion of the pilot. Extended flight beyond the nearestapproved landing area is not recommended.12-19AUTOROTATIONSBoth straight-ahead and turning autorotations shouldbe practiced by reference to instruments. This trainingwill ensure that you can take prompt corrective actionto maintain positive aircraft control in the event of anengine failure.To enter autorotation, reduce collective pitch smoothlyto maintain a safe rotor r.p.m. and apply pedal trim tokeep the ball of the turn-and-slip indicator centered.The pitch attitude of the helicopter should be approximately level as shown by the attitude indicator. Theairspeed indicator is the primary pitch instrument andshould be adjusted to the recommended autorotationspeed. The heading indicator is primary for bank in astraight-ahead autorotation. In a turning autorotation, astandard rate turn should be maintained by reference tothe needle of the turn-and-slip indicator.COMMON ERRORS DURING AUTOROTATIONS1. Uncoordinated entry due to improper pedal trim.
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发表于 2009-3-21 00:07:03
2. Poor airspeed control due to improper pitch attitude.3. Poor heading control in straight-ahead autorotations.4. Failure to maintain proper rotor r.p.m.5. Failure to maintain a standard rate turn during turning autorotations.SERVO FAILUREMost helicopters certified for single-pilot IFR flight arerequired to have autopilots, which greatly reduces pilotworkload. If an autopilot servo fails, however, youhave to resume manual control of the helicopter. Howmuch your workload increases, depends on whichservo fails. If a cyclic servo fails, you may want to landimmediately as the workload increases tremendously.If an antitorque or collective servo fails, you might beable to continue to the next suitable landing site.INSTRUMENT TAKEOFFThis maneuver should only be performed as part ofyour training for an instrument rating. The proceduresand techniques described here should be modified, asnecessary, to conform with those set forth in the operating instructions for the particular helicopter beingflown.Adjust the miniature aircraft in the attitude indicator,as appropriate, for the aircraft being flown. After thehelicopter is aligned with the runway or takeoff pad, toprevent forward movement of a helicopter equippedwith a wheel-type landing gear, set the parking brakeor apply the toe brakes. If the parking brake is used, itmust be unlocked after the takeoff has been completed.Apply sufficient friction to the collective pitch control tominimize overcontrolling and to prevent creeping.Excessive friction should be avoided since this limitscollective pitch movement.After checking all instruments for proper indications,start the takeoff by applying collective pitch and a predetermined power setting. Add power smoothly andsteadily to gain airspeed and altitude simultaneously andto prevent settling to the ground. As power is applied andthe helicopter becomes airborne, use the antitorque pedals initially to maintain the desired heading. At the sametime, apply forward cyclic to begin accelerating toclimbing airspeed. During the initial acceleration, thepitch attitude of the helicopter, as read on the attitudeindicator, should be one to two bar widths low. The primary and supporting instruments after becoming airborneare illustrated in figure 12-22. As the airspeed increases405060 7080901001101200102030TORQUEPERCENTPrimaryPowerPrimary PitchSupporting BankSupporting PitchSupporting BankSupporting PitchSupporting Pitch Primary BankFigure 12-22. Flight instrument indications during an instrument takeoff.12-20to the appropriate climb airspeed, adjust pitch graduallyto climb attitude. As climb airspeed is reached, reducepower to the climb power setting and transition to a fullycoordinated straight climb.During the initial climbout, minor heading corrections should be made with pedals only until sufficient airspeed is attained to transition to fullycoordinated flight. Throughout the instrument takeoff, instrument cross-check and interpretations mustbe rapid and accurate, and aircraft control positiveand smooth.COMMON ERRORS DURING INSTRUMENTTAKEOFFS1. Failure to maintain heading.2. Overcontrolling pedals.3. Failure to use required power.4. Failure to adjust pitch attitude as climbing airspeed is reached.13-1Flying at night can be a very pleasant experience. Theair is generally cooler and smoother, resulting in betterhelicopter performance and a more comfortable flight.You generally also experience less traffic and less radiocongestion.NIGHT FLIGHT PHYSIOLOGYBefore discussing night operations, it is important youunderstand how your vision is affected at night andhow to counteract the visual illusions, which you mightencounter.VISION IN FLIGHTVision is by far the most important sense that youhave, and flying is obviously impossible without it.Most of the things you perceive while flying arevisual or heavily supplemented by vision. The visualsense is especially important in collision avoidanceand depth perception. Your vision sensors are youreyes, even though they are not perfect in the way theyfunction or see objects. Since your eyes are notalways able to see all things at all times, illusions andblindspots occur. The more you understand the eyeand how it functions, the easier it is to compensate forthese illusions and blindspots.THE EYEThe eye works in much the same way as a camera. Bothhave an aperture, lens, method of focusing, and a surface for registering images. .Vision is primarily the result of light striking a photosensitive layer, called the retina, at the back of the eye.The retina is composed of light-sensitive cones androds. The cones in your eye perceive an image bestwhen the light is bright, while the rods work best in low
