Is this function working with heli as well? Anyone tried before and is it working well for heli?
Thanks in advance.
It should work for helicopters like it works for any other copter aircraft. There are limitations and the guidelines for Plane apply:
http://ardupilot.org/copter/docs/common-terrain-following.html
Note that due to the accuracy limitations of the SRTM data it is not wise to use it flying below about 60 meters. I have not personally used it, as I prefer to do my flight planning using USGS survey data when available and set the altitude at the waypoints manually. This is the wiki entry describing its use in Copter with LIDAR