Warning! - Check your pitch fork pin tightness

[red_z06]

I was testing Justin's H550 at a funfly. After few piroflips some stress testing (pitch pumping etc), there was a loss of tail control. It did not spin out as in normal loss of tail but it just would not rotate from one position.

I managed to bring it down to about 3ft and hit the throttle hold. The tail just spun out and did a boomstrike upon hitting the ground.

The damage was rotor blade, boom support, boom and see-saw linkage ball screw flew out.

The cause was the pitch fork pin slipped out. I have checked the other side that was intact and it too was loose and with minimal force I can push it out. Sitting in the sun made the black plastic expand enough to let the pin just slip out. The pin should either have one way washers pushed in from both sides (like MA) or shoulder screw with nut locktighted. Or it should have tighter fit with pitch fork hole.

I temporarily put a drop of CA in the link to prevent fall out.

[Finless]

Many helis with this config use either C clips or one side has a head on it and the other side has a C clip. BUT I hate those clips as they are a pain to work with.

The Align design uses a shouldered screw which I have NOT seen a problem with yet. At first I didnt trust that design but I havent seen one unscrew yet so it appears to be a good idea. Hmmm I wonder if the Align screws will work on this? I might have a look see.

Thanks for sharing!

Bob

[tungym]

All pins, screws to plastic must be CA. The washout guiding pin is another site that will come loose. Also, the 45 degree plastic arm connecting swashplate has another pin.