Originally Posted by
RVDT
"snow" is a fairly broad generalisation. There are vastly different types.
I spent some time talking to I think it was the guys from Dart at AHI in Grand Prairie TX who had just completed FAA certification on the filter for the AS350B3.
They had been up in Canada and it is actually pretty involved and difficult.
Maybe AHD used the "
wrong type of snow"
The FAA requires the warm wet snow -4 to 1°C, 1/4 mile visibility, 20 minutes on the ground, 5 minutes IGE, 1 hour flying max safe speed (as fast as you dare in essentially zero visibility). There's also the cold dry snow test, which I think Transport Canada is pushing. Either test requires a good meteorologist and lots of sitting around waiting for the right conditions.
Sikorsky with the S-76 C++ ended up doing both the warm wet snow and the cold dry snow in its certification of the IBF.