Odd radio incident, Or not.

[J D 8 - Moderator]

I went flying at the club strip on Friday early to make use of calm conditions for some vintage model flying, then cutting grass. In the afternoon as wind picked up brought out my Citabria pro, Pretty 55"span chunky flyer that does not mind a bit of wind. Power is only an OS LA40 so take off can be quite long, however once in the air it is fine with engine flat out most of the time.

  I had been flying a while doing usual stuff when was on a slow decent on the downwind leg ready to turn in for a low pass up the strip when suddenly model flicked to the right and headed in a spiral down.[ one turn] Instinct took over I straightened up but there was not the height to recover so shut the throttle.

       As luck would have it crashed nose well down into a patch of knee high tussock grass    which absorbed the impact, anywhere else, hard surface or trees beyond I recon there would not be an issue to address just bits to pick up.

  As we walked to the crash site I thought I had been caught out going too slow in a gusting cross wind but when at the model first thing that caught my eye was both ailerons were [radio still on] drooped one about 20 degrees other 15. Apart from a cracked cowl there was no other damage even prop is fine.

 First thought was heck stripped gears in ail servos or splines gone but no, double checked and good

  As can bee seen in pic Tx stick is central but both ailerons are drooped. Any comments as to what the issue may be. John.

[kc]

My first thought was if it's just one central servo then this had failed in some way.  Or the aileron horn had come loose or servo has come loose.    But if it's two servos then I would look into the Tx memory to see if some mix had been set and inadvertantly been switched in whilst recovering model. 

[RottenRow]

Do both ailerons still work normally in both directions, but now with that offset?

 

Are the ailerons operated by a single servo, or two separate ones? And if the latter, are they on a Y-lead or on two separate channels?

 

Brian.

[john stones 1 - Moderator]

Nose down impact tends towards somethings moved, can clevices be moved under pressure, are the splines on the servo horns o.k, are horns still at 90 degrees ?

[MattyB]

48 minutes ago, J D 8 - Moderator said:

I went flying at the club strip on Friday early to make use of calm conditions for some vintage model flying, then cutting grass. In the afternoon as wind picked up brought out my Citabria pro, Pretty 55"span chunky flyer that does not mind a bit of wind. Power is only an OS LA40 so take off can be quite long, however once in the air it is fine with engine flat out most of the time.

  I had been flying a while doing usual stuff when was on a slow decent on the downwind leg ready to turn in for a low pass up the strip when suddenly model flicked to the right and headed in a spiral down.[ one turn] Instinct took over I straightened up but there was not the height to recover so shut the throttle.

       As luck would have it crashed nose well down into a patch of knee high tussock grass    which absorbed the impact, anywhere else, hard surface or trees beyond I recon there would not be an issue to address just bits to pick up.

  As we walked to the crash site I thought I had been caught out going too slow in a gusting cross wind but when at the model first thing that caught my eye was both ailerons were [radio still on] drooped one about 20 degrees other 15. Apart from a cracked cowl there was no other damage even prop is fine.

 First thought was heck stripped gears in ail servos or splines gone but no, double checked and good

  As can bee seen in pic Tx stick is central but both ailerons are drooped. Any comments as to what the issue may be. John.

Maybe you had a flapeton mix setup  and switched it in by accident? Is it reproducible now on the ground? . Have you gone through all the mixers in your Tx setup?  And have you range checked the system since the incident? 

Edited September 15 by MattyB

[MattyB]

Also check the fail safe springs by switching off the radio and seeing where the controls move to. Do the ailerons drop in that situation? 

[J D 8 - Moderator]

  The ailerons are operated via two in wing servos short rod to control surface on separate channels.  They operate as normal but now have offset [ this could have triggered the loss of control of model perhaps] Rx is Futaba R2006. 

The only programs operating in this model are the dual aileron and some CAR, rudder and elevator are as should be. No duel rates or expo being set. 

  John S, Horns, splines servo gears are good double checked.

  MattyB, Flaperon is inhibited. Not done range check since incident but situation still the same TX next to model.

   The only thing that moves when failsafe operated is the throttle shutting as set to do so, The drooped ailerons remain in drooped position and do not move neither do rudder or elevator.

[J D 8 - Moderator]

  Just been trying TX with 3 other aircraft that have similar two ail servo set up, all normal.

[Phil Green]

Put the radio aside for now, check the aileron servos individually, feed them 1500uS from a tester and my bet is that the arm will not be central, maybe skipped spline or jumped gear.

[john stones 1 - Moderator]

Somethings moved to give that droop, you took servo cover off and inspected ?

 

[kc]

If both are drooped then with 2 separate servos then it must be in the Tx memory  as long as the hinges and both TE hinge spars have not moved ( aileron looks a bit low on the part nearest camera  compared to inner section)   I suppose it's possible both servo mounts have loosened if they are fitted to the same spar.

Edited September 15 by kc

[J D 8 - Moderator]

JS, Yes have removed servo covers, Servos are firmly fixed to covers. It is odd that both are affected, the impact with the tussock grass did not even break the prop.

PG, Both servo arms are central with control surface set to line up with wing [done by hand] I am a bit old school that way with

mechanical set up of controls. As soon as radio is on both servo arms and therefor ailerons move to droop position.

PG, No issue with ail alignment just the pic.

    Thinking this is most likely a radio issue, thinking of the flight that during it I felt model was rather sensitive in the roll and trim not right, could it be that issue was already developing? Controls were fine during preflight check.

[kc]

With Futaba which does not have ' Model Match'  it's posible to fly with the wrong model memory - so that's a thing to check.........

[john stones 1 - Moderator]

So alls square until radios switched on, you had a look flapperon screen/switch, not done owt daft ?

 

[J D 8 - Moderator]

                 Kc, not that one, right at the time and right since.

                 JS, Flaperon INH not activated for this model.

               Giving it up for now TX needs charging anyway. Oh and RX batt tested still 89%.

[MattyB]

44 minutes ago, kc said:

With Futaba which does not have ' Model Match'  it's posible to fly with the wrong model memory - so that's a thing to check.........

Highly unlikely imo given he got so far into the flight before  experiencing the issue. Personally for such a simple model I would just set it up again from scratch in a clean model memory as that willmau be e simpler than trying to find a setup gremlin in the Tx. Alternatively, have you d the servo Subtrin  values in whatever menu covers that? 

Edited September 15 by MattyB

[john stones 1 - Moderator]

If you flew other models same day with no issues, would be looking at changing RX and see what it says.

[J D 8 - Moderator]

              Hi Matty, Checked sub trims all at zero, Model was set up mechanical way. Last thing I did was clear model memory and reset, had to reverse ail and elevator but that was all. CAR still off. still the same.

John, Only flew my Veron Cardinal which has no ailerons but rudder operated from Ail stick no issues. Have tested TX with other twin ail servo planes today all fine.  Next thing will be to swap out the RX.

 

[Richard Harris]

I've had this happen with an 8FG, had to keep retrimming between flights on all of my models in its memory. Ailerons would be off centre each time the transmitter was turned on by quite a bit and throw in one direction slowly reduced.

Seemed to be pointing at the roll pot.  Have since bought another transmitter but been given a second hand 8 to transfer the parts to hopefully get some more life out of it.

[MattyB]

17 minutes ago, Richard Harris said:

I've had this happen with an 8FG, had to keep retrimming between flights on all of my models in its memory. Ailerons would be off centre each time the transmitter was turned on by quite a bit and throw in one direction slowly reduced.

Seemed to be pointing at the roll pot.  Have since bought another transmitter but been given a second hand 8 to transfer the parts to hopefully get some more life out of it.

Wow, and I thought mechanical build quality and bullet proof reliability were supposed to be the  given with Futaba that justified the higher price? I’ve never had any issue similar to that  on  >10 years of flying the “Challenger brands” from China!

Edited September 15 by MattyB

[J D 8 - Moderator]

  Hi Richard, I have had my T8j a good number of years and this is the first issue with it. Only this model affected so far, tests with others have shown no problems but may well try a flight long test moving controls while on the ground with my Limbo  which has similar set up given what you say.

[Martin Harris - Moderator]

Have you activated a flight mode from a long forgotten experiment?

[i12fly]

Don't think this helps but..... I have a twin aileron model with New Power servos, model stood for some time (2 yr?). On powering up one servo drooped about 20 degrees as if the centring was haywire. Servo worked up and down from this 'new' centre. George at 4max suggested it was the pot at fault, something he'd heard of on New Power after a lay up. I didn't feel like risking a cure so I scrapped the NP servos... 

[MattyB]

10 hours ago, i12fly said:

Don't think this helps but..... I have a twin aileron model with New Power servos, model stood for some time (2 yr?). On powering up one servo drooped about 20 degrees as if the centring was haywire. Servo worked up and down from this 'new' centre. George at 4max suggested it was the pot at fault, something he'd heard of on New Power after a lay up. I didn't feel like risking a cure so I scrapped the NP servos... 

Yes, servo pot failurew is absolutely a possibility, though the chances of that ha[ppening in two different  servos at precisely the same time (within mins of each other having passed a pre-flight check  would seem very low. 

[Dickw]

How a bout swapping the connectors around at the receiver (e.g swap one aileron and rudder, and one aileron and elevator) to see if the offset follows the servos or stays with the Rx port. That should confirm if a radio or a servo problem.

 

Dick