Exercise 23 - Sloping Ground

From: Transport Canada

GROUND SCHOOL POINTS

  1. Dynamic Rollover
  2. Flight Manual - Limitations
  3. Tail Rotor Drift and Roll

PREPARATORY INSTRUCTION

Aim

For the student to learn procedures and techniques for operating from sloping ground.

Review

Exercise 8, 9 and 10.

Motivation

    1. Describe the helicopter's ability to operate from unprepared surfaces and sloping ground. Explain that pilots are frequently required to use this ability under operational conditions.
    2. Explain that sloping ground techniques, involving as they do, gentle and cautious control movements, are very suitable for landing on any type of doubtful surface (e.g. packed snow, muskeg, etc.).

Airmanship

    1. Lookout - obstacles
    2. W/V
    3. Aircraft limitations

Teaching Points

Explain that sloping ground operations can be divided into 4 phases:

    1. reconnaissance;
    2. manoeuvring;
    3. landing; and
    4. take-off.
  2. Reconnaissance:
    1. Explain that all landing surfaces require careful attention during landing and take-off. Extra care must be taken where the surface is likely to be soft, slippery, or where there are obstacles such as rocks or tree stumps.
    2. Describe how cross-slope landing performance is affected by cyclic control limitations and the fact that one skid hangs lower than the other at the hover.
    3. Explain that landing into wind is always desirable for aircraft handling, but that there are often occasions when the pilot must "trade-off" wind and slope in order to get the best compromise between the ground and aircraft limitations.
    4. Point out that in view of the above, it is vital to make a careful assessment of the ground before attempting to land.
  3. Manoeuvring
    1. Point out that the tail assembly is particularly vulnerable during sloping ground operations. Pilots should be constantly aware of the tail rotor, particularly when making hovering turns, when landing upslope in conditions where the ground levels out behind the helicopter, or when landing downslope.
  4. Landing
    1. Describe the landing performance and limitations of the training helicopter type.
    2. Describe how to land on sloping ground as follows:
      1. establish a steady hover;
      2. lower collective gently until the upslope skid contacts the ground;
      3. continue lowering the collective, at the same time moving the cyclic gently towards the slope maintaining a level attitude;
      4. when both skids are in full contact with the ground, smoothly lower the collective until it is fully down.
      5. Prevent yaw throughout.
      6. Carry out a seating check by making small gentle movements of the collective and pedals.
      7. when certain the helicopter will not slide centre the cyclic and reduce RPM, if required.
    3. Point out the need for smooth and accurate control movements and for not overcontrolling. Explain that it is possible to induce a rate of roll, with one side of the landing gear in contact with the ground, that is impossible to counteract with opposite cyclic.
    4. Describe the symptoms that cyclic control limits are being reached due to excessive slope. Explain that when they start to occur, or if the aircraft starts to slide, the helicopter should be brought smoothly back to the hover and landed elsewhere.
    5. Point out the importance of maintaining flying RPM until the collective is fully down and seating checks are complete.
    • Take-off
    1. Describe how to take off from sloping ground, as follows:
    2. ensure that the RPM is at the take-off setting;
    3. level the rotor disc so that it is parallel with the horizon;
    4. raise the collective gently and ease the cyclic away from the slope keeping the aircraft level, so it breaks contact with the ground vertically. Stress the vital importance of avoiding any lateral movement; and
    5. prevent yaw throughout.
    • Operational Considerations
    1. Point out the dangers of turning rotor blades to persons in the close vicinity of the helicopter in this type of operation, and in particular, embarking and disembarking passengers. Explain that it is the pilot's duty to brief passengers and ground crew in this regard, whenever possible.
    2. Review the dangers of dynamic rollover and the need to ensure before take-off, that the helicopter is within C of G limits and that the landing gear is clear of snags and obstacles.
    3. Explain that in some operational conditions, it will not be necessary or desirable to centralize the cyclic after landing or even, in some cases, to lower the collective completely.

Confirmation 

PRE-FLIGHT BRIEFING

AIR LESSON
    1. Select an area of sloping ground well within the helicopter's limits and demonstrate reconnaissance of, and manoeuvring over, the intended landing area.
    2. Student practice.
    3. Demonstrate cross-slope landings in both directions, pointing out the difference in aircraft performance where appropriate.
    4. Student practice.
    5. Demonstrate an up-slope landing.
    6. Student practice.
    7. Select an area of sloping ground that is close to aircraft limits and demonstrate landings and take-offs.
    8. Student practice.
    9. Select an area of sloping ground that is beyond aircraft limits and demonstrate the indications that the limits are being approached, and the methods of aborting the landing.
    10. Student practice.
    11. Demonstrate wind/slope trade-off.
    12. Student practice of reconnaissance and selection of landing points.

POST-FLIGHT DEBRIEFING

TIPS FOR INSTRUCTORS
    1. The performance and techniques involved with different types of helicopter on sloping ground varies. This exercise should be tailored to meet the performance of the training helicopter.
    2. Students tend to be very tense when introduced to sloping ground operations. They will be likely to overcontrol and will tire quickly. It is vital that the student is proficient at hovering and standard take-offs and landings before this exercise is introduced.
    3. Students will tend to look at the ground close to the aircraft. Overcontrolling frequently results and it will often be necessary to remind the student to raise his eyes and use the horizon as a datum.
    4. When the student is proficient, let him make the decision where to land to judge his ability to evaluate slopes.
    5. Start the student on `beginners slopes' and gradually increase the severity as proficiency improves.
    6. Ensure that 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.

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