450 crash question

[ianmat]

Well today I had my first ever proper crash as my Trex 450 decided to fly itself into the ground... nothing to do with me whatsoever (honest!!!). So new main shaft, tail boom, tail belt, tail rotor shaft, oh and new main gear as I completely freaked out and didn't hit throttle hold, so lots of stripped teeth.
I have already taken the poor heli apart and replaced the main shaft, but when I spin the head, it looks like the new shaft is bent? Tried a second new shaft and it looks the same... the hand stop on the top of the rotor head wobbles all over the place. There's no obvious play in the main bearings and both shafts were brand new genuine align parts... any ideas??

[jimmyhorns]

Hmmm sounds a bit odd. Remind me, where abouts are you?... I can pop round on my way home from work and take a look if you like... would be about 9.15pm

[tourerjim]

Have you checked the feather shaft, way to check is to turn the shaft & your see the blade grip/s move up n down.

[pug907]

Sorry if this sounds daft, but the same thing was happening to a friends heli last week, he stripped everything numerous times( as you prolly have) before he gave it to me to look at. The base of the head button had been flattened on one side and screw was bent, so it was giving the illusion that shaft was bent, as it was running elliptically! Take it off and try again .
Cheers,

[ianmat]

I'll whip th feathering shaft out and take a look.
Thanks Jimmy, but I'm heading out this evening with the missus. I'm pretty sure it's just my eyesight!!!

[bikerflier]

Often the holes for the button are not true. I never fit the button, can damage blade grips in a crash.
Maybe the rotor housing bent, is it a snug fit on the shaft, sometimes the slot gets forced open a little.
If the main shaft bent it is certain the main bearings need replacing.
Hold the main shaft slightly tilted just in the bearing and turn the shaft, if it feels gritty the bearings need changing.
Same if the feathering shaft bent, the blade holder bearings need changing.
Thrust bearings usually survive OK.
And again, same with the tail shaft bearings.
Surprised if the main shaft bent without the feathering shaft also bending.

RC Bearings are reasonable bearings at a fair price, cheap postage and very good service.

[ianmat]

I've just stripped out the feathering shaft and rolled it on a sheet of glass, It's fine... the main bearings feel smooth as well, however it looks like the top of the head just above the end of the main shaft is bent, as I spin the whole lot I can see the blade grips are not in line any more... typical, how much is a new head going to set me back.

[bikerflier]

Depends which 450 it is.
Link to Midlands for an idea but make sure you go for the correct one for your heli.

450PRO FL V2 Main Rotor Housing Set/Black | Midland Helicopters Ltd

I've just stripped out the feathering shaft and rolled it on a sheet of glass, It's fine... the main bearings feel smooth as well, however it looks like the top of the head just above the end of the main shaft is bent, as I spin the whole lot I can see the blade grips are not in line any more... typical, how much is a new head going to set me back.

[ianmat]

Ok I've just taken the button off and now all looks fine, as you said Biker I think that's bent. I find it hard to imagine that the fairly solid machining has been bent...

[trexamanic]

you can check for true by sticking a pin with blue tac to the frame touch it to the shaft and as it spins check for any movement

[pug907]

After a crash, sometimes the shaft will "dig" in to the rotor yoke, so no matter how much you tighten it, there will be slop. The hole gets elongated. It's only ally. If that happens, you can repair it with chemical metal and use an old shaft to ream the stuff to shape before it sets. Just make sure you push the shaft past where it normally sits whilst twisting it in. I've done this a few times and you get a few more prangs out of it lol. I'm glad it was only the button, as I suggested it might be. Bloody things.