ok guys i been flying planes for years and have tinkered with low-end helis in the past will i finally made the plunge and got a trex 450se will i been down with it over tail blades flying off (shattering in flight) well while i was wating parts i traded for a blade 400 and another trex 450xl i think(it's ccpm) anyway i been flying the blade like i stole it well good forward flight anyway
well i finally got the parts for my trex today and i took it out to fly i got abought a 3 minutes of good hover and same thing thistime it threw the tail assembly at me and twisted the gearcasing at the end of the boom upward i checked all the possibles but find nothing causing this problem (but like i said i'n not real good at heli's yet) if anyone has any ideals please let me know
i do not have a rpm guage yet and was wondering if too muck head speed could cause this anyway your thoughts would be greatly appreciated.

I would recommend you go over the Trex 450 build videos at Helifreak done by Finless Bob, and the safety section. After 15 yrs of planes, I have found helis to be very different machines. Good Luck, Andy

thats the thing i've went over what seems like hundreds of videos and i thought everything was right and safe
i thought it was headspeed but i reduced the rpms until i barley had enough to fly and it still threw the tail off (it actually broke the bolt in the blade grip)
i'm wondering if this was just a mis-hap or do i need another upgrade everything is metal now

Take the idler pully out or get one with raised edges, some of the clone 450's came with them. In my experience the (smooth) idler pully would let the belt walk off of the drive pully and wad up between the side of the case/pully. It works fine without the idler. I believe Align put somthing out a few years back about this. If you have a picture of the damage, post it if you can. I can't remember having a belt take out a case before, other than me slamming into somthing as a dirrect result of the belt coming apart, (or any of the thousands of other reasons I have found to do so). You say the boom was bent upward, you could be running your tail rotor backwards because the belt should be pulling down on the end of the boom if the rotor was to stop. The tail rotor should spin in the dirrection that if the bladed were to touch the ground, the dirt would fly twards the front of the heli like a wheel in reverse. The fact that the tail has come apart twice in a row has me thinking something like that is what happened. (Don't ask me how I might have learned to look for those kind of things!)

I had that exact problem. The belt kept slipping off to the right side and kept chewing the belt up (replaced every time). The first time it happened, I managed to save the heli. Second time, it quickly lost power, I had no time to bring it down safely, it locked up and fell to the ground.

Old Crashman is correct. There are two methods that "should" fix the problem.

Some believe it might not be a good idea to take the pulley out since align must have had some reason for having it in the design. It might fix the problem and not hurt anything, however... even safer in my opinion, what I did was got an idler pulley with raised edges as mentioned.

What I got is unfortunately discontinued
http://www.eboyztoyz.net/index.php?op=showitem&sku=6701

I believe I read when I was researching the same problem that this also fits and works perfect
http://www.eboyztoyz.net/index.php?op=showitem&sku=8844

No problems since changing it.

I don't use a pulley on either of my 450's. I have the T rex se v2 and the exact copy of that, the EXI 450 carbon edition. Works fine, I have not had any problems yet.

Make sure you locktite every screw and nut!!!! I missed 1 on the tail of my 250 and it came apart just like your describing. Don't assume the factory did it chances are they did not.

KZ