I installed a new set of propellers I bought from dji.  And noticed a bit of a vibration.  I figured it was ok to fly.  And i'd look into buying one of them devices to balance the props.  Flew over open water no problem.  Landed back home.  And while inspecting my Phantom I noticed one propeller only seats half way down the shaft.  Defective propeller.  And I flew it like that.  LOL..  Operator error for sure to fly.  Won't let that happen again. Using force I was able to get the propeller to seat all the way down the shaft.  But now I'm inclined to chuck it in the trash.  It seats with some effert, but I'm afraid the hub will crack in flight.  I sent an email off to dji support.  I hope they find it in thier heart to replace the propeller.  

It might be a good idea to check the locking device on the motor shaft, as the propeller may not be the only part that was damaged.

Which drone do you have? As you posted under Phantom 3.There is no locking device on the Phantom 3 motor shafts, or rotors, so it must be a defective thread in the rotor blade hub.

Do other rotor blades screw on smooth and down tight? Or lock down firm.

Don't throw it out, get them (where you purchased it) to replace the pair of blades. ;-)

RedHotPoker

I have 3 sets of rotor blades.  All fit perfect except for just the one blade.  I have a Phantom 3 Pro.  It is a defective blade.  End of story.  

glad it was a short story

Emergency over...New Day