Originally Posted by
hoistop
We have got significant damage on a 206 during auto training on grass. When landed, the aft part of BOTH skids dipped in a sort of potholes, that were left behind by agricultural machinery-tractor, that dug two holes in a distance, exactly matching skids distance. (obviously made by tractor wheels that dug into softened soil during last rain) Potholes were perfectly hidden in grass. When collective was lowered, heli tilted backwards resulting in abrupt stick-forward reaction. A severe mast-bumping followed so mast, M/R Hub, XMSN mounts etc. had to be replaced. You never know what is hiding in the grass as long as it is not verified every time.
As a glider pilot, I was taught never to try out-of-airport landing on the grass, however temptating, if a plowed field is available too. This came with decades of experience. (and many damaged planes)
Which just goes to show that in aviation there is seldom a "one size fits all" answer. I would not let my Bulldog students even practice forced landings to a ploughed field (in case the engine didn't pick up). Experience had showed that the type (low wing, nose wheel, SEP with a sliding canopy) was quite likely to nose over on a soft surface and if it did, there was no chance of getting out unaided. Getting burned alive by leaking AVGAS whilst hanging upside down certainly wasn't how I wanted to end my days.
Different types, such as a high wing with side doors (Cessna 152 etc), maybe.