Originally Posted by
TwinHueyMan
Scary thing is, if it was the Van Horn bounce, putting the collective down only makes things worse. The info letter put out about it less than a month ago says the harmonic is the same natural frequency as the tailboom.
Van Horn 206L MRB IL
Pictures I've seen of a suspected VH bounce that got on the ground has severe damage in the same area of the tailboom that was the break point on the New York machine.
If I was a TSB investigator, I would be heading in this direction. I've had collective bounce in a 206L induced by turbulence and it felt like the helicopter was going to break apart in flight. I was happily flying straight and level and then pretty much instantly bouncing up and down with my seat belt and shoulder harness holding me in from the extreme ups and downs. When bouncing like that, your instinct is to hold on to the collective which actually makes things worse. To get out of it, I used the palm my hand and pushed the collective down. This stopped the bounce pretty much instantly. I always make sure I've got a bit of collective friction on now... Here's another report from someone who wasn't so fortunate -->
https://www.tsb.gc.ca/eng/rapports-r.../a08p0265.html We had van Horn blades on a 206B and the premature wear on bearings and flight controls in less than 1000 hours was like nothing we'd ever seen on 30k + hours of 206B time in our fleet. We no longer operate VH blades on anything.