Is ground resonance a thing of the past?
 

With the advent of new technology on helicopters such as the EC135, is ground resonance still a significant hazard to beware of or is it limited solely to aircraft with oleo's?

Yes it is a hazard to be aware of and is not limited to aircraft with oleo undercarriages. Infact the EC135 AFM does contain a warning concerning this.

Thanks...
 

Thanks for clarifying that GG, to extend the discussion a stage further, are there any conditions are likely to induce this??

I got ground resonance in a brand new AS-350 b3
It only had about 75hrs TT and would get ground resonance on a regular basis. As I was the only pilot flying this aircraft for it's entire 75 hrs the local agent and manufacturer blamed yours truly for not landing it correctly....It took the manufacturers highly paid engineer 3 atemps to find the cause (which was not me) but the "oleo" plus the fact that I flew it back to the manufacturers base with the owner and watch him demand his US $1.5m back.. That was a great site!!

I'd be keen to see what 'new technology' the 135 employs to combat ground resonance.

The 350 series is famous for it, and those little steel tabs that hang off the back of the skid tubes are useless in off-pavement situations. I've seen more than a few of these things riverdance their way into the pilot's long-term memory.

On skid equipped ships, the Hughes 500 series is fairly immune to it with the lunar landing gear it has. As are the newer Bells with the three point mount (407, 427, 412). GR is virtually unheard of in these aircraft.