Loss of tail control ?

[SamS]

Last time I flew my 130x was the other and all looked fine before the flight.

Whilst in the air I completely lost all tail control, it just slowly started spinning as though I lost the tail rotor, managed to get it on the ground, but when I land, the tail initializes then, and control movements are fine, but it seems as though in the air the til doesn't isn't initialized and my inputs do nothing.

Again, when I land, the tail then twitches and initializes, I spool up and I still have tail, it's only when I'm off the ground, I have no tail control ...

Anyone had the same issue ?

[Geek]

Sam you sure it's not a striped gear?

[SamS]

Nope, that's what I thought at first Paul, but the gear has all its teeth ..

[sp4rky-m4rky]

I have had similar on a larger heli, caused by binding in the pitch mechanism paried with a weak servo. The tail sat fine before take off but at the tail revs increased the force needed to change the pitch increased untill the load it put on the servo was too much. If you have the main blades off and pop the link off the tail servo, spool it up and adjust the tail pitch by pushing and pulling the controll rod by hand, spool it to full revs after and see how hard the servo is having to work. If it is really tough then you just need to work out what is causing it and sort that. I was amazed at the force required to change the tail pitch on my 450 even with everything running smooth.

[Idle Jack]

check the inside D of the gear as it's more likely to strip than the teeth, i also had my tail behave like that when one of the screws had started to come undone on the tail blade grips

[C8RLS]

Also try moving the tail servo ever so slightly rearwards on the boom, this worked for one of mine that started loosing the tail for no obvious reason.

[Jez N]

I suspect the TT is rotating in the D gear. Had a similar problem the other day and that was the cause. Check the other obvious which is that the servo hasnt moved and the tail is still at 0 degrees with no rudder input with equal throw left and right

[danch]

I suspect the TT is rotating in the D gear. Had a similar problem the other day and that was the cause. Check the other obvious which is that the servo hasnt moved and the tail is still at 0 degrees with no rudder input with equal throw left and right

One of the members at our club had this on Sunday checked every thing & turns out that the TT was rotating occasionally in the d gear

New d gear & all ok

[Scooby]

What they said - it sounds like the tail gear on the TT (not the tail shaft) is slipping - I think its the C gear.
Had the same with mine, fine on the ground but once in the air it started to spin, and once it started it got faster and faster. Took the C gear off and the D shape had become an O. A new C gear fixed it.
I think what happened was as the pitch of the tail rotor changed it increased the load on the tail shaft, which caused the gear to slip, which slowed the rotor, which caused an increase in pitch, which further increased the load and so on.

[tomatwalden]

Nope, that's what I thought at first Paul, but the gear has all its teeth ..

It's not the teeth that strip. I'd lay money on this being your issue. Hold the main gear still, then try to turn the tail rotor. If you can with minimal pressure, your "C" gear has stripped.

The stripping happens within the gear - it's the "D" shape hole that keeps it tight on the torque tube. The externally visible gears will look fine.

I've done 3 so far (usually from take-off's in grass)

[SamS]

Okay so I've replaced the c and d gear, Nd the issue is still there, it's like the tail only initializes on the ground, once in the air, there's no movement.

[tomatwalden]

Okay so I've replaced the c and d gear, Nd the issue is still there, it's like the tail only initializes on the ground, once in the air, there's no movement.

That's kind of odd. I'd guess its something to do with the AS3X unit then. On the ground, all control inputs (cyclic, collective, rudder) are all directly applied. Once the motor starts spinning, the gyros take control.

The symptoms seem to imply that the tail gyro isn't playing nicely. That'd be a new 3-in-1 board to prove it though ... That's an expensive part to buy just for diagnosis!

[tomatwalden]

Okay so I've replaced the c and d gear, Nd the issue is still there, it's like the tail only initializes on the ground, once in the air, there's no movement.

If you hold the main gear and try to turn the tail rotor - does it hold, or can you spin the tail rotor with no movement of the main gear?

[SamS]

Yes it holds, it didn't, but I've replaced the gears and it hold, but it still spins whilst in the air :/

[tomatwalden]

Yes it holds, it didn't, but I've replaced the gears and it hold, but it still spins whilst in the air :/

Then I guess if it's nothing mechanical (and you have re-attached the servo ball link under the tail! ) then you're back to troubleshooting the electronics.. Seems a bit of a coincidence that the tail gear was slipping. So there was obviously a mechanical aspect to it ?

If you spin the heli up whilst holding on to it (maybe remove main blades!) - do the tail respond to yaw inputs?