直升机飞行手册 Helicopter Flying Handbook

时间：2014-11-09 12:30来源：FAA 作者：直升机翻译 点击：次

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During the hover, heading indicators can be checked for freedom of movement and correct indications and the freedom of the slip indicator can be verified. The proper operation of the attitude indicator can be checked during the hover by gently pitching the nose of the helicopter up and down and rolling from side to side.
Instrument Check
The pitot-static system and associated instruments—airspeed indicator, altimeter, and vertical speed indicator—are usually very reliable. Errors are generally caused when the pitot or static openings are blocked. This may be caused by dirt, ice formation, or insects. Check the pitot and static openings for obstructions during the preflight. Turn indicators and magnetic compass are also important components of attitude instrument flying. Instrument checks ensure reliability of these instruments.
Airspeed Indicator
During the preflight, ensure that the pitot tube, drain hole, and static ports are unobstructed. Before lift-off, make sure the airspeed indicator is reading zero. If there is a strong wind blowing directly at the helicopter, the airspeed indicator may read higher than zero, depending on the wind speed and direction. As takeoff begins, make sure the airspeed indicator is increasing at an appropriate rate. Keep in mind, however, that the airspeed indication might be unreliable below a certain airspeed due to rotor downwash.
Altimeter
Before lift-off, set the altimeter to the current setting. If the altimeter indicates within 75 feet of the actual elevation, the altimeter is generally considered acceptable for instrument use.
Turn Indicator
The needle portion of the turn-and-slip indicator shows direction of turn and rate. [Figure 12-1] For instance, if the needle is centered on the standard rate turn marking, the helicopter will complete a 360. turn in 2 minutes. [Figure 12-2] Another part of the turn-and-slip indicator is the inclinometer. The position of the ball defines whether the turn is coordinated or not. The helicopter is not in a coordinated turn any time the ball is not centered, and usually requires an input to the antitorque pedals and angle of bank to correct it.
Figure 12-2. In a coordinated turn (instrument 1), the ball is centered. In a skid (instrument 2), the rate of turn is too great for the angle of bank, and the ball moves to the outside of the turn. The pilot must decrease right pedal and add left pedal to center the ball. Conversely, in a slip (instrument 3), the rate of turn is too small for the angle of bank, and the ball moves to the inside of the turn. The pilot must add left pedal to center the ball.
During preflight, check to see that the inclinometer is full of fluid and has no air bubbles. The ball should also be resting at its lowest point. Since almost all gyroscopic instruments installed in a helicopter are electrically driven, check to see that the power indicators are displaying off indications. Turn the master switch on and listen to the gyros spool up. There should be no abnormal sounds, such as a grinding sound, and the power-out indicator flags should not be displayed. After engine start and before lift-off, set the direction indicator to the magnetic compass. During hover turns, check the heading indicator for proper operation and ensure that it has not precessed significantly. The turn indicator should also indicate a turn in the correct direction.
Magnetic Compass
The magnetic compass is one of the basic instruments required by Title 14 of the Code of Federal Regulations (14 CFR) part 91 for both VFR and instrument flight rules (IFR) flight. The compass can be one of two types: wet (the compass is suspended in fluid) or vertical.
Prior to flight, ensure a wet compass is full of fluid. During hover turns, the compass should swing freely and indicate known headings. Because a magnetic directional indicator is required for all flights, any malfunctions must be corrected prior to flight.
Helicopter Control and Performance
Helicopter control is accomplished by controlling the aircraft’s attitude and power output. Attitude is the relationship of its longitudinal and lateral axes to the earth’s horizon. When flying in instrument flight conditions, the pilot controls the attitude of the helicopter by referencing the flight instruments and manipulating the power output of the engine to achieve the desired performance. This method can be used to achieve a specific performance level enabling a pilot to perform any basic instrument maneuver. The instrumentation can be broken up into three different categories: control, performance, and navigation.

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