204 Tail Rotor Pitch Change
"Tail Rotor pitch change if you still have the 204 style gearbox. In the enclosed photo the pitch change rod on the right is excessively worn.
The one on the left is new. The rods are steel and it takes a lot to wear them this much. The housing they spline into are aluminum and wear much faster. The housings are harder to see the wear inside, they mostly in the middle of their spline.
If the splines are worn too much it will allow the pitch change rod to turn in the housing thus you lose tail rotor control. I have seen housings and rods excessively worn and even fail. It seems people don’t know how to inspect them properly.
They should be checked every 100 hrs or phase depending on your inspection method"