at a loss tail going right and
 

Hi to start I have a trex 450XL a futaba 401 with a futaba S9650 rudder servo . all was well ran out a battery . went and did some other stuff in the shop .Then took out a freshly charged 3s 2200 pack . and started to hover all was good for a few seconds then the tail started to turn right or counter clock wise. so with adding some left rudder stick I found it of no help . I quickly set it down and unplugged the battery thinking maybe my gyro didnt set . also I run in heading hold mode. I tried again with the same results . before lifting off checking the rudder movement it works great but as soon as i lift off it slowly starts to turn spin right . and if I land and watch the ruder servo there is no rudder movement with left stick input only right input . I have no idea what to look for here . I checked all my wires and connectors all looked good and made no changes.

RE: at a loss tail going right and
 

You might want to check your tail drive gear. That's the small gear in the front that meshes with the larger one below the main gear. If you have the plastic one, it could be stripped. The plastic ones are known for that. It's the small plastic hub that the belt wraps around and like I said, if it's plastic, they tend to strip and slip on the metal shaft. Another thing could be a loose set screw on the tail rotor hub. Both of these will probably still turn the tail rotor, but not with enough authority to counter the torque of the main blades. Or you could have a loose belt. If you hold onto the tail rotor and try to turn the main blades they shouldn't turn. If you can turn them, then it's one of those 3 things. Alan

RE: at a loss tail going right and
 

Hi Alan Thanks for the info . your are right on with the tail drive . I held the main gear and tried to rotate the rotor blades and they turned fairly easy. the inside splines on the drive gear for the belt was stripped. I think it maybe was due to the belt being too tight . thanks for the info

RE: at a loss tail going right and
 

having a belt too tight can definitly cause this problem, however, the same thing happened to me in the middle of some tic-tocs and i ended up plowing into a building at work. my belt tends to be kept a little on the loose side so i think it was just the pulleys time to go (unfortunatly for my wallet). its definitly worth the $$ to get the SE V2 drive pulley as a replacement as i now have to shell out $200 in repairs.

good luck, wraith

RE: at a loss tail going right and
 

Ouch ! I hear that. minor repairs suck a little but crashes really suck .

RE: at a loss tail going right and
 

try checking the contorl horn on the rudder i checked mine after i tore it down and replaced a few parts. i realized i had no right control spinning like a top at least i did not crash it when i move dthe control horn forward i had allthe authority.