I can add one to this list:
On a torque tube tail, rotate the mains during pre-flight to confirm the tail blades spin too and therefore that the TT is engaged. Could have averted a crash by doing just that. First crash on that heli too and totally preventable.
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KDS Chase 360 - μBeast+ - Scorpion - HW 50A - KST 215MG - MKS DS95i
Blade 230S / 180 CFX / mSR X / mSR
XK K110 / Phoenix / DX6i