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Helicopter Flight Training Manual (TP 9982)

EXERCISE 10 - HOVERING EXERCISES

In this exercise you will learn how to perform the following manoeuvres:

  1. turns at the hover; and
  2. hover-taxiing.

Manoeuvring close to the ground is very much part of the helicopter environment and you will find that these manoeuvres are carried out as a matter of course.

During the exercise, bear in mind the following airmanship points to include that you:

  1. ensure the manoeuvring area is flat and free of any obstacles that could present a hazard to the tail rotor;
  2. monitor the engine instruments to ensure that no limitations are exceeded; and
  3. anticipate the effect of wind.
PEDAL TURNS AT THE HOVER (TURNS AROUND THE MAST)

Begin your pedal turns from a stable hover, preferably with the helicopter facing into wind. Look out to ensure the surrounding area through which the tail rotor will pass is clear of obstacles that could present a hazard. Start the turn by applying pedal to rotate the helicopter in the desired direction: to turn left apply left pedal, to turn right apply right pedal. Control the rate of the turn with pedal; that is: less left pedal to reduce the rate of a left turn, and vice versa. The amount of pedal required will vary with the strength of the wind. To stop the turn, apply opposite pedal, and then stabilize using pedals as required maintaining the heading. In strong winds weathercocking will cause the rate of turn to increase as the nose passes 180 degrees to the wind. Throughout the turn the cyclic is used to maintain position over the ground as you learned in previous hovering exercises. If there is a wind, the helicopter will tend to drift downwind; therefore you will have to displace the cyclic into the wind to counter this tendency during the turn. The stronger the wind the more cyclic is required.

Collective is used to maintain height in the turn. In strong winds, more frequent power’s changes will be required to maintain height.

In some piston engine helicopters the throttle may have to be adjusted to maintain the correct operating RPM as you manipulate the pedals and collective during the 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.

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.