I have the exact same issue - the helicopters are uncontrollable 
All helicopter related assistance options are on.
Thied both types of flight models: Modern and Legacy - both work bad for helis
Also tried to switch my Custom contoller setup to the presets called Default and Logitech Extreme 3d (Helicopter) - no luck as well.
Is there anything else to try?
Thanks!
PS I’m using the Steam version, running on Windows 10
Hm… something stragne has just happened. I swithced to the Realistic global preset and the helicopters became flyable! I managed to take off for the first time, fly forward, do some turns and even land! Then I swithced back to the Modern Flighnt Mode instead of Legacy and… it still works fine! I looks like the sim needed some sort of reset that was acheived by switching different flight modes back and forth. Not 100% sure about that, but if somebody also has similar issues - that’s what you can try!
Thank you for confirming that it’s not something that affects everybody, and that the assist system should make the helicopter stay on rail and avoid much of the cyclic/rudder work for the player, which is not something us, who are facing the issue, see.
There’s definitely something wrong. Either something on the system of the affected people, or a combination of specific PC and a specific bug in MSFS
dont use the old flight-model with the new helicopter 
OMG, gonna test right now!
Worked like a charm for me too!!! Thank you so much!!
To the people affected; try @ToweringClover1 solution : switch to historical/realistic flight model, fly 5 seconds with it, then switch back to modern FM… voila!
Helicopters now flyable for me
@ToweringClover1 OMG yes!!! All good now! Soooo many thanks for that 
Excellent to hear that you found a fix! Happy flying!
Helicopters : There is definitvely an issue for some of us.
Here with Modern Flight Model, empty Community folder, tested with honeycomb yoke , then thrustmaster Hotas, using cyclic Axis commands ( vs plane commands), setting Sensitivity of joystick to different values ( “an helicopter is drived with the stick witihan an euro coin” ) with myself having a pretty good experience of helicopter.
=> No way to takeoff. some erratic / unexplained move.
Maybe not related but who knows… i have “Network disconnetion” message and reconnect after a while. In the same time a “ping - t google” is showing 2/3ms with burst at 15ms without loosing any frames …
Allo Asobo , there is an ISSUE ! ([FR] Asobo c’est la cata !)
config : AMD Ryzen 9 5950X , 380Ti, 64go RAM, 1to SSD, Honeycomb A&B +, not used in this test but connected : VR G2, + saitek radio + saitek thorttle quadrant ( more buttons…), saitek Radio.
So the above mentioned solution did not work for you? Did you change the flight model back and forth or did you leave it the way it was set before the update?
Why are people using legacy model in the first place? That should never be used. I’m amazed by the amount of people that was using this and having problems with the helis.
Nobody was using the legacy model …
The people with issues used the modern model, it’s just that a fix for the issue is to switch to legacy, then switch back to modern…
Many thanks!
Nope, many people were using legacy.
don’t feed the troll
And you know that from?
I really wish I could like your post 100x
Thank you SO SO MUCH, m8!
I have tried using the Bell Model 407 over 12 times now and I too have experience the issue of, out of control twirling… Notice that everytime I load the Heli the HSI is not balanced but sit slightly left of the two lines… This also shows in the Yaw indicator. XBOX SX
Who is the troll, you?
