Figure 10-1: 360o degree Hovering Turn
It is important that you anticipate the effect of the wind, as the helicopter will tend to align itself with the wind direction. This “weather-cocking” effect is caused by the wind pushing against the vertical fin and body in the same fashion as a weather vane. This will cause a variation in the amount of pedal required as the turn progresses through a full circle, and is most noticeable when the helicopter is at 90 degrees to the wind direction (Fig 10-1).
The continuous use of high power in this exercise means that a careful watch should be kept on the engine temperatures and pressures. Prolonged hovering out of wind, specifically downwind should be avoided because of carbon monoxide poisoning. Check the helicopter flight manual for any such limitations.
In strong gusty wind conditions a turn away from the into-wind position should be opposite to torque reaction, i.e.: to the left in a North American helicopter. In this way you will ensure that there is sufficient tail rotor control available. Should control limits be reached at this stage, a safe turn back into wind can be accomplished.
HOVER-TAXIING
Light single engine helicopters are hover-taxied at the normal hover height of 3 to 5 feet skid height. For safety considerations it is desirable to hover-taxi at a slow speed; approximately a normal walking pace. This is important as:
1. a walking pace will allow the pilot to maintain precise control and will avoid operating the helicopter near translation; and
2. the helicopter attitude will be horizontal, or nearly so. Therefore in the event of an engine failure no attitude change will be required for a safe touchdown.
To begin taxiing ease the cyclic slightly forward, and as the helicopter begins to move, adjust the cyclic to maintain a walking pace. The pedals are used to maintain an accurate heading. In crosswind conditions, a combination of pedals and cyclic will be required to keep the helicopter moving in a straight line across the ground (Fig 10-2). The skids should be tracking parallel to the direction of movement. Collective is used to maintain a constant height throughout the manoeuvre. When taxiing downwind, it is important that you control the ground speed to maintain the walking pace.
Figure 10-2: Fuselage alignment with direction of hover-taxi
To stop forward movement, ease the cyclic slightly aft. It will be necessary to anticipate where you wish to stop because of the lag between cyclic input and helicopter response. This is due to the inertia of the helicopter itself. Make the required cyclic movement small; there is no need to flare the helicopter.
All cyclic movements should be small and smooth; avoid rapid and excessive aft applications of cyclic to ensure that you do not put the tail rotor in jeopardy.
If you are flying a piston engine helicopter, the throttle may have to be adjusted to maintain the correct RPM as the collective and pedals are manipulated.
Your instructor will demonstrate the sequence of events to you and the desired pilot reaction:
1. verbal warning; it is good airmanship to precede the practice emergency with the announcement “practice engine failure”;
2. close the throttle;
3. counteract the yaw and any tendency to drift with opposite pedal and cyclic; and
4. as it sinks, cushion the helicopter onto the ground by increasing the collective.
NOTE: Ensure that the skids are parallel to the direction of travel for the touchdown to avoid the possibility of a rollover.
5. after touchdown, hold the controls until the helicopter has come to a complete stop, then lower the collective pitch to the full down position and move the cyclic and pedals to the neutral position.
EXERCISE 12 - TRANSITIONS
This exercise is the basis of many others and the skill learned will be used in almost every flight you make from now on in your career. Your instructor will review:
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