Piro of death

[hedge]

Any one had a similar issue. I am used to servos locking up or burning out but I've not had one freak out. On Sunday the tail locked full right, I managed a hard landing - broke back skid support and the tail blades. When I got to it the heli - not crashed so was upright - it was all still working. The tail servo had over driven it's (FBL) set end points and had popped the tail rod link off and was moving back and forth with no input from me. When I rebooted the system it stopped moving on its own and just works? I looked at the Spartan log and all is well so I am confused. Do I need a new tail or a new FBL? Anyone else seen this? Hundreds of normal flights leading up to this but I've Been looking for a slight twitch in the tail over the last few weeks which I had thought was mechanical - any ideas??

[bigpops]

I have a crash from the other week that I've only been able to put down to a servo fault. It was an Align DS610.

My 7HV went from a hover 20ft up to full negative into the ground. I've had my Vbar tested by Mikado, and it's fine. No missed signals or sensor errors. My transmitter logs that log stick positions and RSSI were all fine.

Other than the expected air frame damage (1 lower frame/skids/canopy/main shaft, spindle and one lipo which smoked a cell), the damage was a locked up servo. No popped or bent links, and even the servo arm (the Mikado carbon reinforced ones) didn't break. It was also stripped, but even with a new gear set it's no good and still locks up without power.

The only thing I can think of is the servo failed and locked fully down. The Mikado guy said that if that happened, the Vbar would see it as an outside force and try to maintain attitude. That would have the side effect of putting negative pitch on the blades.

I'd have the FBL tested for peace of mind, and replace the tail servo or have that tested too if it's feasible.

[dodeye]

Any one had a similar issue. I am used to servos locking up or burning out but I've not had one freak out. On Sunday the tail locked full right, I managed a hard landing - broke back skid support and the tail blades. When I got to it the heli - not crashed so was upright - it was all still working. The tail servo had over driven it's (FBL) set end points and had popped the tail rod link off and was moving back and forth with no input from me. When I rebooted the system it stopped moving on its own and just works? I looked at the Spartan log and all is well so I am confused. Do I need a new tail or a new FBL? Anyone else seen this? Hundreds of normal flights leading up to this but I've Been looking for a slight twitch in the tail over the last few weeks which I had thought was mechanical - any ideas??

Hi similar thing happened to me a month ago on my rappy e700 just saved it apart from skids n main blades , I also thought servo problem but when I stripped Heli down I notice the pin that goes through tail gear shaft in main frame end had come out , you could turn head by hand and all seemed fine but when under real load it just spun on shaft had my head done in , the grub screw that holds it in came loose . Not saying same thing happened to you but something to check that's if it's not belt driven of course

[hedge]

Thanks dodeye, sounds nasty, in my case it's the servo freaking as opposed to a hw failure. I guess at least with a tail failure you have a chance of saving it where as with a cyclic it's game over.

[dodeye]

Thanks dodeye, sounds nasty, in my case it's the servo freaking as opposed to a hw failure. I guess at least with a tail failure you have a chance of saving it where as with a cyclic it's game over.

No probs . I was inverted when mine went mental still don't know how I saved it lol

[GravityKills]

A poti failure can do that.

[trexamanic]

thats a hard one to solve.
why not spin her up minus the blades and look at what is happening with the servo.
If you can adjust the pot both ways to see if it impacts hugely
the servo is easy enough tested.
goodluck

[Holst]

Unless the servo is mega expensive I would replace it.
Not worth taking the risk of another crash.

It's unlikely the fbl is faulty but it might be worth emailing the manufacturer just to ask if there is any fault that could cause the servo to ignore the set end points.

These sort of faults are really annoying as I'm worried they will reoccur.

Good luck.

[hedge]

Unless the servo is mega expensive I would replace it.
Not worth taking the risk of another crash.

It's unlikely the fbl is faulty but it might be worth emailing the manufacturer just to ask if there is any fault that could cause the servo to ignore the set end points.

These sort of faults are really annoying as I'm worried they will reoccur.

Good luck.

i managed to get hold of Angelos on Helifreak and he said the SPARTAN cannot overdrive the servo. That only leaves the servo so I will replace and test and fly - cautiously :-)