直升机飞行训练手册 HELICOPTER FLIGHT TRAINING MANUAL(47)

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LANDING 
In preparation for the landing you must establish a steady hover over the selected spot (Figure 23-2). Gently begin to lower the collective, allowing the helicopter to settle until the uphill skid contacts the slope. Pause slightly. Now as you further lower the collective, you must also progressively move the cyclic towards the slope keeping the rotor-disc parallel to the horizon. This will prevent the helicopter from sliding down the slope. It is possible to exceed the limits of cyclic travel at this point, or you may find that the helicopter begins to slide. Should this occur, smoothly lift the helicopter into a hover clear of the slope and select another landing spot. If sufficient cyclic control remains, continue to lower the collective until the downslope skid contacts the ground. Throughout the landing manoeuvre, ensure that you prevent yaw with use of pedals. Once on the ground, carry out a “seating check” by making small and gentle movements of both pedals and collective. Do not centre the cyclic, or roll back the throttle, until you have performed the seating check and you are satisfied that the helicopter is not going to slide. Under some conditions (e.g. dropping off passengers and leaving) it may not be desirable to centre the cyclic or carry out the seating check, nor roll back the throttle.
 

 
Figure 23-2: Landing-Uneven Terrain 
 
It is most important that your control movements are smooth and accurate, and that you avoid any tendency to over control as it is possible to set up a roll rate, especially about the skid in contact with the slope, which could then lead to dynamic rollover that opposite cyclic could not counteract.
 
TAKEOFF
In preparation for the takeoff, carry out the pre-takeoff checks, and ensure that the rotor RPM is correctly set. Before beginning to gently raise the collective, level the rotor-disc, so that it is once again parallel to the horizon. The downslope skid will begin to rise; in the reverse of the landing sequence (fig 23-2), the cyclic must now be progressively moved away from the slope as the collective is being raised. Coordinate the movements of the two controls, so that the helicopter smoothly breaks contact with the ground and rises vertically into the air. Maintain direction with the pedals and ensure that all lateral movement is eliminated, avoiding the possibility of a dynamic rollover situation.
GENERAL

 
Figure 23-3: Dynamic Rollover 
 
Your instructor will review with you the conditions that could lead to dynamic rollover and  the avoidance techniques. It is important that your helicopter has been properly loaded and is within CG limits, both laterally and longitudinally, as an out-of-limits helicopter could lead to a situation favourable to dynamic rollover. For similar reasons, the importance of smooth, gentle control movements while ensuring that the skids are clear of snags and obstacles, and the importance of maintaining RPM at maximum will be stressed.
It is possible to exceed the cyclic control limits when performing slope landings. When moving the cyclic towards the slope you may:
1. feel the cyclic physically restricted from further travel; or
2. encounter mast bumping or droop stop pounding. This will manifest itself through a thumping noise at the rotor head and vibrations.
Do not continue to attempt to land under these circumstances, but lift off again to the hover.

 
Figure 23-4: Disembarking Passengers
 
Your instructor will discuss with you the potential hazards of embarking or disembarking passengers while the helicopter is on a slope. The rotor blades are very close to the ground on the uphill side and present a real hazard to passengers. Brief your passengers of the direction to take and remain within your view the whole time.
 
EXERCISE 24 - ADVANCED TAKEOFFS AND LANDINGS
The techniques in this section are usually employed because of operational situations and conditions. A good rule of thumb is to only employ them when necessary.
　
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