直升机教员手册 Helicopter Instructor’s Handbook
时间：2014-11-10 08:35来源：FAA 作者：直升机翻译 点击：次
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To view this page ensure that Adobe Flash Player version 9.0.124 or greater is installed. The performance and techniques involved with different types of helicopter on sloping ground vary. This exercise should be tailored to meet the performance of the training helicopter. Students tend to be very tense when introduced to sloping ground operations, are likely to overcontrol, and tire quickly. Before introducing this exercise, ensure the student demonstrates proficiency at hovering and standard takeoffs and landings. Instructional Points Prior to performing this maneuver, several briefings and discussions should take place. The first point to discuss is the student’s depth of understanding of dynamic rollover. As previously stated, take time to discuss the reasons and events that lead up to dynamic rollover. Let the student lead the discussion and determine his or her level of understanding. Does the student simply apply rote memorization in the discussion or does there appear to be a level of understanding that leads to application and correlation? The second vital discussion centers around the decision and procedure of aborting the maneuver. As already stated, the student will be tense during the maneuver. Discussion on the proper flight control inputs required to recover the aircraft is essential to safe execution of the maneuver. The third discussion should be about where to go after the maneuver was terminated and then to analyze why the maneuver was aborted. Remember to provide positive, meaningful feedback to the student. Make the initial approach to the slope at a 45° angle to check the suitability of the landing site. At the termination of the approach, move the helicopter slowly toward the slope, being careful not to turn the tail upslope. Position the helicopter across the slope at a stabilized hover headed into the wind over the spot of intended landing. Maintain heading with proper antitorque pressure, using caution to not overcontrol with the pedals. Ensure the student relates left yaw inputs as a critical condition for dynamic rollover in helicopters with counterclockwise rotating rotor systems. Downward pressure on the collective starts the helicopter descending. As the upslope skid touches the ground, hesitate momentarily in a level attitude, then apply lateral cyclic in the direction of the slope. This holds the upslope skid against the slope while the downslope skid is lowered with the collective. Ideally, the student understands that by keeping the rotor disk level, the lift vector is kept in a near vertical state. As the collective is lowered, continue to move the cyclic toward the slope to maintain a fixed position. The slope must be shallow enough so the helicopter can be held against it with the cyclic during the entire landing. A slope of 5° is considered maximum for normal operation of most helicopters. Be aware of any abnormal vibration or mast bumping, which signals maximum cyclic deflection. If this occurs, abandon the landing because the slope is too steep. In most helicopters with a counterclockwise rotor system, landings can be made on steeper slopes when the cyclic is being held to the right. When landing on slopes using left cyclic, some cyclic input must be used to overcome the translating tendency. If the wind is not a factor, consider the drifting tendency when determining landing direction. After the downslope skid is on the surface, reduce the collective to full down, and neutralize the cyclic and antitorque pedals. In helicopters requiring manual throttle manipulation, normal operating rpm should be maintained until the full weight of the helicopter is on the landing gear. This ensures adequate rpm for immediate takeoff in case the helicopter starts sliding down the slope. Use antitorque pedals as necessary throughout the landing for heading control. Before reducing the rpm, move the cyclic control as necessary to make sure the helicopter is firmly on the ground. Once proficiency has been demonstrated, let the student make the decision as to where to land. This allows the instructor to judge the student’s ability to evaluate slopes. Start the student on a shallow slope and gradually increase the difficulty level as proficiency improves. Ensure the student is shown some slopes which are a mix of cross slope and up/down slope, so that the helicopter has to be landed diagonally on the slope. Common Student Difficulties Overcontrolling The student’s concern about the possibility of sliding or overturning usually leads to more uphill cyclic input than is required. The effects of excessive cyclic are not noticeable as the collective is lowered, since the helicopter has no tendency to slide uphill, but the limits of cyclic travel may be reached earlier than if the student were using only enough uphill cyclic to prevent sliding. Loss of Reference Students tend to look at the ground close to the aircraft. Overcontrolling frequently results and it is often necessary to remind the student to raise his or her eyes and use the horizon as a reference. Slope Takeoff The takeoff from a slope is much easier than the landing because the helicopter is already resting on the slope. [Figure 11-8] The student must be briefed not to turn away from the slope while still at a hover because this moves the tail toward the slope. Have the student slide away from the slope and conduct a turn about the tail to ensure the tail is clear of the sloping terrain. Begin by initiating the climb on the takeoff heading or, if obstacles dictate taking off downslope, move sideward before beginning the turn. Instructional Points Begin the takeoff by increasing rpm to the normal range with the collective full down, then move the cyclic toward the slope. Position the cyclic to level the rotor disk and apply enough lateral cyclic to hold the landing gear on the slope in position as the collective is slowly increased. As the skid comes up, move the cyclic toward the neutral position. If properly coordinated, the helicopter should attain a normal attitude as the cyclic reaches the neutral position. At the same time, use antitorque pedal pressure to maintain heading and throttle to maintain rpm. With the helicopter at a normal hovering attitude and the cyclic centered, pause momentarily to verify everything is correct, and then gradually raise the collective to complete the lift off. |
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