Rotorcraft Flying Handbook, FAA-H-8083-21

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RECIPROCATING ENGINES Fuel is delivered to the cylinders by either a carburetor or fuel injection system. CARBURETOR In a carburetor system, air is mixed with vaporized fuel as it passes through a venturi in the carburetor. The metered fuel/air mixture is then delivered to the cylinder intake. days with temperatures as high as 38°C (100°F) and the humidity as low as 50 percent. However, it is more likely to occur when temperatures are below 21°C (70°F) and the relative humidity is above 80 percent. The likelihood of icing increases as temperature decreases down to 0°C (32°F), and as relative humidity increases. Below freezing, the possibility of carburetor icing decreases with decreasing temperatures. Carburetors are calibrated at sea level, and the correct fuel-to-air mixture ratio is established at that altitude with the mixture control set in the FULL RICH position. However, as altitude increases, the density of air entering the carburetor decreases while the density of the fuel remains the same. This means that at higher altitudes, the mixture becomes progressively richer. To maintain the correct fuel/air mixture, you must be able to adjust the amount of fuel that is mixed with the incoming air. This is the function of the mixture control. This adjustment, often referred to as “leaning the mixture,” varies from one aircraft to another. Refer to the FAA-Approved Rotocraft Flight Manual (RFM) to determine specific procedures for your helicopter. Note that most manufacturers do not recommend leaning helicopters in-flight. Ice Venturi Ice To Engine Fuel/Air Mixture Ice Most mixture adjustments are required during changes of altitude or during operations at airports with field elevations well above sea level. A mixture that is too rich can result in engine roughness and reduced power. The roughness normally is due to spark plug fouling from excessive carbon buildup on the plugs. This occurs because the excessively rich mixture lowers the temperature inside the cylinder, inhibiting complete combustion of the fuel. This condition may occur during the pretakeoff runup at high elevation airports and during climbs or cruise flight at high altitudes. Usually, you can correct the problem by leaning the mixture according to RFM instructions. If you fail to enrich the mixture during a descent from high altitude, it normally becomes too lean. High engine temperatures can cause excessive engine wear or even failure. The best way to avoid this type of situation is to monitor the engine temperature gauges regularly and follow the manufacturer’s guidelines for maintaining the proper mixture. CARBURETOR ICE The effect of fuel vaporization and decreasing air pressure in the venturi causes a sharp drop in temperature in the carburetor. If the air is moist, the water vapor in the air may condense. When the temperature in the carburetor is at or below freezing, carburetor ice may form on internal surfaces, including the throttle valve. [Figure 5-10] Because of the sudden cooling that takes place in the carburetor, icing can occur even on warm Incoming Air Figure 5-10. Carburetor ice reduces the size of the air passage to the engine. This restricts the flow of the fuel/air mixture, and reduces power. Although carburetor ice can occur during any phase of flight, it is particularly dangerous when you are using reduced power, such as during a descent. You may not notice it during the descent until you try to add power. Indications of carburetor icing are a decrease in engine r.p.m. or manifold pressure, the carburetor air temperature gauge indicating a temperature outside the safe operating range, and engine roughness. Since changes in r.p.m. or manifold pressure can occur for a number of reasons, it is best to closely check the carburetor air temperature gauge when in possible carburetor icing conditions. Carburetor air temperature gauges are marked with a yellow caution arc or green operating arcs. You should refer to the FAA-Approved Rotorcraft Flight Manual for the specific procedure as to when and how to apply carburetor heat. However, in most cases, you should keep the needle out of the yellow arc or in the green arc. This is accomplished by using a carburetor heat system, which eliminates the ice by 5-7
outing air across a heat source, such as an exhaust manifold, before it enters the carburetor. [Figure 5-11]. Filter To Carb Helicopters have either a 14- or 28-volt, direct-current electrical system. On small, piston powered helicopters, electrical energy is supplied by an enginedriven alternator. These alternators have advantages over older style generators as they are lighter in weight, require lower maintenance, and maintain a uniform electrical output even at low engine r.p.m. [Figure 5-12] Door Carb Heat Off Filter To Carb Carb Heat Collector Manifold Pipe Avionic Bus (Optional Avionics) Avionics Relay Avionic Bus Bar Door Heated Air Carb Heat On Carb Heat Collector Manifold Pipe Figure 5-11. When you turn the carburetor heat ON, normal air flow is blocked, and heated air from an alternate source flows through the filter to the carburetor. FUEL INJECTION In a fuel injection system, fuel and air are metered at the fuel control unit but are not mixed. The fuel is injected directly into the intake port of the cylinder where it is mixed with the air just before entering the cylinder. This system ensures a more even fuel distribution in the cylinders and better vaporization, which in turn, promotes more efficient use of fuel. Also, the fuel injection system eliminates the problem of carburetor icing and the need for a carburetor heat system. TURBINE ENGINES The fuel control system on the turbine engine is fairly complex, as it monitors and adjusts many different parameters on the engine. These adjustments are done automatically and no action is required of the pilot other than starting and shutting down. No mixture adjustment is necessary, and operation is fairly simple as far as the pilot is concerned. New generation fuel controls incorporate the use of a full authority digital engine control (FADEC) computer to control the engine’s fuel requirements. The FADEC systems increase efficiency, reduce engine wear, and also reduce pilot workload. The FADEC usually incorporates back-up systems in the event of computer failure. ELECTRICAL SYSTEMS The electrical systems, in most helicopters, reflect the increased use of sophisticated avionics and other electrical accessories. More and more operations in today’s flight environment are dependent on the aircraft’s electrical system; however, all helicopters can be safely flown without any electrical power in the event of an electrical malfunction or emergency. Mag Switch G Off L R Both – + 24V Battery Battery Switch R L Battery Relay Starting Vibrator Ret Adv Adv Starter Relay Clutch Actuator (Internal Limit Switches Shown in Full Disengage Position) On Off Avionics Master Switch Left Magneto Right Magneto Engine Starter Starter Release Switch Hold M/R Gearbox Press Switch Engage Clutch Switch Alternator – + Ammeter Alternator Control Unit Lights Panel Position Beacon Trim Instr Lndg Lt Radio Xpdr Clutch Turbine powered helicopters use a starter/generator system. The starter/generator is permanently coupled to the engine gearbox. When starting the engine, electrical power from the battery is supplied to the starter/generator, which turns the engine over. Once the engine is running, the starter/generator is driven by the engine and is then used as a generator. Current from the alternator or generator is delivered through a voltage regulator to a bus bar. The voltage regulator maintains the constant voltage required by the electrical system by regulating the output of the alternator or generator. An over-voltage control may be F2 F1 Bus Bar Alternator Switch Figure 5-12. An electrical system scematic like this sample is included in most POHs. Notice that the various bus bar accessories are protected by circuit breakers. However, you should still make sure all electrical equipment is turned off before you start the engine. This protects sensitive components, particularly the radios, from damage which may be caused by random voltages generated during the starting process. 5-8
Page 2: ROTORCRAFT FLYING HANDBOOK 2000 U.S
Page 6 and 7: HELICOPTER Chapter 1—Introduction
Page 8 and 9: Technique..........................
Page 10 and 11: Collision Avoidance at Night.......
Page 12 and 13: Helicopters come in many sizes and
Page 14 and 15: Main Rotor Wake Air Jet Downwash Li
Page 16 and 17: There are four forces acting on a h
Page 18 and 19: Increased Local Velocity (Decreased
Page 20 and 21: Load Factor - "G's" 9 8 7 6 5 4 3 2
Page 22 and 23: Once a helicopter leaves the ground
Page 24 and 25: otation and blade deceleration take
Page 26 and 27: lift and thrust are greater than we
Page 28 and 29: Relative Wind Retreating Side Blade
Page 30 and 31: Bank Angle Vertical Component of Li
Page 32 and 33: percent of the radius. In the drive
Page 34 and 35: Note: In this chapter, it is assume
Page 36 and 37: The rotor disc tilts in the directi
Page 38 and 39: By knowing the various systems on a
Page 40 and 41: If the first and second stage turbi
Page 42 and 43: The horizontal hinge, called the fl
Page 46 and 47: incorporated to prevent excessive v
Page 48 and 49: depends on the temperature of the o
Page 50 and 51: Title 14 of the Code of Federal Reg
Page 52 and 53: l0 5 l5 20 25 30 35 MANIFOLD PRESSU
Page 54 and 55: It is vital to comply with weight a
Page 56 and 57: sive forward displacement of cyclic
Page 58 and 59: Once you are satisfied that the tot
Page 60 and 61: Basic Empty Weight Pilot Fwd Passen
Page 62 and 63: Your ability to predict the perform
Page 64 and 65: Approximate Density Altitude - Thou
Page 66 and 67: the entire flight operation. Being
Page 68 and 69: From the previous chapters, it shou
Page 70 and 71: 2. brief passengers on the best way
Page 72 and 73: VERTICAL TAKEOFF TO A HOVER A verti
Page 74 and 75: Control pressures and direction of
Page 76 and 77: HOVER TAXI A "hover taxi" is used w
Page 78 and 79: 3. Assuming an extreme nose-down at
Page 80 and 81: tain altitude and r.p.m. As the tor
Page 82 and 83: Start Turn At Boundary Turn More Th
Page 84 and 85: the helicopter is being crabbed int
Page 86 and 87: APPROACHES An approach is the trans
Page 88 and 89: The maneuvers presented in this cha
Page 90 and 91: TECHNIQUE Refer to figure 10-2. To
Page 92 and 93: COMMON ERRORS 1. Failing to maintai
Page 94 and 95:
Figure 10-7. Slope takeoff. be cons
Page 96 and 97:
made in the forward portion of the
Page 98 and 99:
Today helicopters are quite reliabl
Page 100 and 101:
After touchdown and after the helic
Page 102 and 103:
HEIGHT ABOVE SURFACE - FEET 500 450
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helicopter, while the relative airf
Page 106 and 107:
When performing slope takeoff and l
Page 108 and 109:
the main rotor blades having an ang
Page 110 and 111:
WEATHERCOCK STABILITY (120-240°) I
Page 112 and 113:
LOW FREQUENCY VIBRATIONS Low freque
Page 114 and 115:
Attitude instrument flying in helic
Page 116 and 117:
ways. If the ram air inlet is clogg
Page 118 and 119:
to true north. Because the aircraft
Page 120 and 121:
AIRCRAFT CONTROL Controlling the he
Page 122 and 123:
vertical speed indicator immediatel
Page 124 and 125:
POWER CONTROL DURING STRAIGHT-AND-
Page 126 and 127:
50 60 70 80 40 TORQUE 90 30 100 20
Page 128 and 129:
to the approximate setting for the
Page 130 and 131:
used, the rate of cross-check must
Page 132 and 133:
AUTOROTATIONS Both straight-ahead a
Page 134 and 135:
{ { Flying at night can be a very p
Page 136 and 137:
White Red Red White Green Red Green
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you are operating off-airport, you
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Aeronautical decision making (ADM)
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THE DECISION-MAKING PROCESS An unde
Page 144 and 145:
Night VFR Accident Rate Per 100,000
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STRESSORS Physical Stress—Conditi
Page 148 and 149:
OPERATIONAL PITFALLS Peer Pressure
Page 150 and 151:
January 9th, 1923, marked the first
Page 152 and 153:
LANDING GEAR The landing gear provi
Page 154 and 155:
Helicopters and gyroplanes both ach
Page 156 and 157:
elative wind striking the advancing
Page 158 and 159:
subject to pendular action in the s
Page 160 and 161:
Due to rudimentary flight control s
Page 162 and 163:
Gyroplanes are available in a wide
Page 164 and 165:
Figure 18-4. This prerotator uses b
Page 166 and 167:
inability to use differential braki
Page 168 and 169:
As with most certificated aircraft
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8 TOTAL TAKEOFF DISTANCE TO CLEAR 5
Page 172 and 173:
The diversity of gyroplane designs
Page 174 and 175:
minimize the length of the ground r
Page 176 and 177:
adjust the fuel/air mixture to achi
Page 178 and 179:
maximum performance is desired, two
Page 180 and 181:
Start Turn At Boundary Turn More Th
Page 182 and 183:
Shallowest Bank UPPER HALF OF CIRCL
Page 184 and 185:
of failing to monitor and maintain
Page 186 and 187:
for the gyroplane. When using the s
Page 188 and 189:
Gyroplanes are quite reliable, howe
Page 190 and 191:
BUNTOVER (POWER PUSHOVER) As you le
Page 192 and 193:
As with any aircraft, the ability t
Page 194 and 195:
leaves few places to safely land in
Page 196 and 197:
GLOSSARY ABSOLUTE ALTITUDE—The ac
Page 198 and 199:
FREE TURBINE—A turboshaft engine
Page 200 and 201:
TRANSLATIONAL LIFT—The additional
Page 202 and 203:
A ABORTED TAKEOFF, GYROPLANE 21-1 A
Page 204 and 205:
turn indicators, 12-4 GYROSCOPIC PR
Page 206 and 207:
R RAPID DECELERATION 10-3 RECIPROCA
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Rotorcraft Flying Handbook, FAA-H-8083-21

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