Originally Posted by
paco
It's less of a problem with teetering heads because they don't have drag dampers - they are actually the most suceptible to GR, but articulated heads have dampers. And contrary to popular belief, you can get it in an AS 350 - a friend of mine got into it on the factory course in the USA of all places. And, as crab says, skids are better than wheels....
I was only involved with two ground resonance incidents both with skidded aircraft.
The first was a Lama in Scotland which had landed for a hot refuel. As I stepped over the skids with the refueling hose and was removing the fuel cap the pilot took off.
I threw the hose clear and walked out round the back of the skids. I stopped to give the pilot a hard stare. On shut down he explained that ground resonance had set in. Probable cause was the
landing site which was a loose gravel track. That could have been worse if the hose had get caught up.
The second was a skidded 365C. Pilot had three goes before getting it safely on the ground. Much work was done but the aircraft continued to want to go into resonance.
Among the work was new set of undercarriage dampers. Eventually a third set of dampers fixed the problem. Apparently the overhaul shop were setting them up incorrectly.