直升機飛行手冊 Helicopter Flying Handbook

時間：2014-11-09 12:30來源：FAA 作者：直升機翻譯 點擊：次

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Operating Limitations (Section 2)
The operating limitations section contains only those limitations required by regulation or that are necessary for 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 oil requirements; weight and loading distribution; and flight limitations.
Instrument Markings
Instrument markings may include, but are not limited to, green, red, and yellow ranges for the safe operation of the aircraft. The green marking indicates a range of continuous operation. The red range indicates the maximum or minimum operation allowed while the yellow range indicates a caution or transition area.
Airspeed Limitations
Airspeed limitations are shown on the airspeed indicator by color coding and on placards or graphs in the aircraft. A red line on the airspeed indicator shows the airspeed limit beyond which structural damage could occur. This is called the never exceed speed, or VNE. The normal operating speed range is depicted by a green arc. A blue line is sometimes added to show the maximum safe autorotation speed. [Figure 5-2]
Another restriction on maximum airspeed for level flight with maximum continuous power (VH) may be the availability of power. An increase in power required due to an increase in weight, or by G producing maneuvers, may decrease VH. A decrease in power available caused by increased density altitude or by weak or faulty engines also decreases VH.
Altitude Limitations
If 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 Limitations
Low rotor revolutions per minute (rpm) does not produce sufficient lift, and high rpm may cause structural damage, therefore rotor rpm limitations have minimum and maximum values. A green arc depicts the normal operating range with red lines showing the minimum and maximum limits. [Figure 5-3]
There are two different rotor rpm limitations: power-on and power-off. Power-on limitations apply anytime the engine is turning the rotor and is depicted by a fairly narrow green band. A yellow arc may be included to show a transition range, which means that operation within this range is limited due to the possibility of increased vibrations or harmonics. This range may be associated with tailboom dynamic modes. Power-off limitations apply anytime the engine is not turning the rotor, such as when in an autorotation. In this case, the green arc is wider than the power-on arc, indicating a larger operating range.
Powerplant Limitations
The powerplant limitations area describes operating limitations on the helicopter’s engine including such items as rpm range, power limitations, operating temperatures, and fuel and oil requirements. Most turbine engines and some reciprocating engines have a maximum power and a maximum continuous power rating. The “maximum power”
Figure 5-3. Markings on a typical dual-needle tachometer in a reciprocating-engine helicopter. The outer band shows the limits of the superimposed needles when the engine is turning the rotor. The inner band indicates the power-off limits.
rating is the maximum power the engine can generate and is usually limited by time. The maximum power range is depicted by a yellow arc on the engine power instruments, with a red line indicating the maximum power that must not be exceeded. “Maximum continuous power” is the maximum power the engine can generate continually and is depicted by a green arc. [Figure 5-4]
The red line on a manifold pressure gauge indicates the maximum amount of power. A yellow arc on the gauge warns of pressures approaching the limit of rated power. [Figure 5-5] A placard near the gauge lists the maximum readings for specific conditions.

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