Spent the last 3 days trying to correct the $#%# that went with this last update.  Finally got the RC and AC talking, finally got the gimbal working, finally got the camera working and now... I lift off and it's whistling like crazy.  I brought it down immediately.  The only thing I can think of is a propeller problem??  I did tip over on the grass, landing a few weeks ago due to a hole hidden by the grass, but have flown since then with the same props.  With no whistling.  I don't even have an hour on these ones.  Suggestions?

Has to be the props, not sure what else it can be.  Could something be lodged under or around the motor?  Anytime the blades come in contact with anything, I change them, even if they do not appeared damaged.   Damage could also occur at the hub of the blade, where it connects to the top of the motor.  

I assume that you've checked the props for dirt or other which may be clinging to them. Just give them a polish and feel for any rough bits on their edges (could have been dented a little).

You may want to try hand spinning the props on the motors and feel for roughness or resistance.That could indicate debris of some kind in the motors which could be removed simply by turning the Phantom upside down and spinning the props or a can of pressurized air.

Sorry for the late response and thank you for your help.  I've changed the props and did all suggested above but there is still whistling.  I've since watched a few youtube videos and some of those birds  are whistling too.  Not all, but some.  It seems to be flying without a problem so I'll just keep my props new and testing the motors before I fly.  Thank you for all the suggestions.

Mine started whistling after the last update. Also have live feed problems since update.

Mcandies Posted at 2017-7-25 15:56
Mine started whistling after the last update. Also have live feed problems since update.

Same here.

Hate to state the obvious but did you try spooling up WITHOUT the props on to see if you still hear it?