Pre Flight Briefing
Limitations
All helicopters have limits to which they can be flown onto sloping ground, these limits may not neessarily be stated in the Flight Manual.
Wind and Slope Relationship, Including Blade And Control Stops
The Effect of C of G When On Slope
The C Of G is the point on the aircraft, where the forces applied to the aircraft are seen to act. Weight always acts towards the center of the earth. If the C Of G is horizontally outside the skid track the helicopter will quite literally topple over. This is known as static rollover. The angle at which this occurs is dependant upon how far apart the skids are, and the lateral and vertical position of the C Of G.
Landing Techniques When On Slope Left, Right and Nose-Up
Leading with the lever.
Feel for the ground.
Apply upslope cyclic to reduce roll rate.
Once skids are down, SLOWLY lower the lever, and centralise the cyclic being aware for any ground slide.
A landing across the slope is less likely to result in a tobogan like slide.
Teetering heads abort the landing if you can feel vibration as the cyclic is moved upslope, you may have hit the teetering stops.
Avoidance of Dynamic Rollover, Dangers of Soft Ground and Sideways Movement
Dynamic rollover is caused by a roll rate developing with a part of the helicopter (usually a skid in contact with the ground).
Care must be exercised not to allow a roll rate to develop which would cause the downslope skid to 'smack' on the ground as the helicopter may continue to rotate about that skid. If a landing is to be aborted DO NOT yank up on the lever while in contact with the ground, this will set up a rolling moment about the skid and may result in a rollover.
Soft ground can cause problems in a number of ways, the helicopter can sink into soft ground and on take off skids may be 'reluctant' to come off the ground, if one skid sticks more than another a dynamic rollover may develop. On landing care must be exercised when lowering the lever due to the possibility that the aircraft may start to slide downhill on softer ground.
Sideways movement should be avoided once again due to the risk of dynamic rollover due to 'snatching' a skid on the ground.
Dangers Of Overcontrolling Near To Ground On Slope
Danger Of Striking Main / Tail Rotor On Up Slope
A tail up slope condition should be avoided, the tail rotor will be closest to the slope if the helicopter faces DOWN the slope.
The upslope side of the main rotor should be treated with extreme caution as a steep slope may cause the tips of the disc to contact the slope.
Particular care should be excercised to unload passengers down the slope and keep them away from the side of the disc which is upslope.