Fly4Fly

Hey Guys,

So I started flying in 03 at which time I had an Avistar 40. Flew great without major issues.

As I re-entered the hobby, I purchased a brand new Avistar Elite RTF, and other items to complete what I would need for the first flight.

My instructor and I ran the flight check and everything checked out.

The engine started up and maintained RPM and everything was a go.
Next,
Plane takes off normally and is in full control, less than 30 seconds into the flight, there seemed to be some sort of electronics failure.
I am trying to figure out, what part more specifically could have caused the issue...
After about 30 seconds, ailerons were reversed, the throttle seemed to be reversed as well or rather did not react appropriately to the input. The reversing effect though was not permanent, but rather intermittent. Basically, it was acting squirley.

My instructor did his best to land the plane, but given the lack of control, this was somewhere in a dense forest preserve.
Unfortunately the plane was unfindable, perhaps lost amongst the forest canopy.

Regardless, I am trying to diagnose the cause of the failure.
My only idea is that the receiver could have been faulty.
Let me know some possibilities and what you think of the Tactic transmitter, receiver, and servos that come with the Avistar Elite RTF.

Any input is appreciated.

Thanks

Tom Nied

Did you do a range test? Almost sounds like a bad switch or battery connection, or the battery itself (low voltage). Just thinking out loud.

Fly4Fly

Hi Tom,
Thanks for the input.
Yes, we did the range check. We also checked the battery voltage before take-off. The connection between the battery and receiver should of been good as well, we used a plastic slip on securer to ensure they would stay connected.
The switch worked fine on the ground.
But again just thinking out loud.
I primarily just don't want to duplicate this loss in the future so let me know if anyone has any other ideas.

Thanks again.

Tom Nied

Range check with the engine running while someone is holding the airplane up and shaking it?

Fly4Fly

No sir. Just while the plane was horizontal and stationary.

Hmm... I think that would of been a good idea.
Although we may never know why it failed, doing that test may have allowed us to rectify it before lift off.

Is there a standardized pre flight check list on the ama site? Or what is the best resource for such information / documentation.

Thanks again

Fly4Fly

lets say that this part of the flight check did not pass. check all connections then? Retest?

Tom Nied

Without the plane, all you can do is speculate. Your description of how it was flying makes me think that there was a momentary loss of battery power. There's a pretty good checklist in the manual for the Avistar Elite RTF on pace 17 http://manuals.hobbico.com/gpm/gpma1605-manual.pdf

Fly4Fly

Yes, that was the checklist that I went through.
It is the last step, But it simply just says range check, I suppose my range check method wasn't as thorough as it should of been.

Tom Nied

Yeah, the range check description for the Tactic TTX600 isn't very descriptive either. Page 12 http://manuals.hobbico.com/tac/tacj2600-manual-v1_2.pdf. I'd have to admit I don't do the shake, but I do like to do the range check with the engine running. Maybe because it was a RTF with the electronics already installed could have done you in. So on the next one, make no compromise, and check everything. I doubt it was a manufacturing fault, more likely a poor connection. Speaking of connections, I always like to wrap the RX with tape or foam and tape to ensure the plugs stay in.

Fly4Fly

Yes, this is all true.
Thanks for the connector suggestion.
My next kit will certainly be an ARF and I am not going to make any compromise. Building an ARF will give me more control over the assembly process. I am not saying there was anything wrong with the RTF Elite, right now we can consider the failure an "act of god"

I appreciate the advice. I will post if I learn anything new about this.

Tdaffy

Is it possible that there was some snafu in the communications between the two radios? That tactic is a wireless trainer system isn't it?
That's actually a pretty good bird, and though the radio is lower end, it and the receiver are not bad. Also, if I remember right, my rtf avistar was very unsteady during trimming. I had to do a lot of mechanical between some pretty wobbly first runs.

Fly4Fly

as far as the snafu you mention, the trainer system was not active for the first test flight. So tht can be ruled out...

When you say mechanical, what are you exactly referring to? Servos, pushrods, ?? The wood construction I assume shouldn't require mch modification . If I knew there was such a high variablitiy in the manufacturing of RTF models, I would of gone with an arf.

Tdaffy

I mean in that trimming was so far, that I had to adjust throws on the push rods some. I never had to mess with the servos, but in particular, the pitch had to be tweaked on the ground. First flight, the thing lifted off like a rocket going for the moon!! Wasn't sure I actually had enough throw on the down pitch to bring it back to earth. It really caught me off guard. Also, it really liked to bank left. Now, I have to admit, I balanced it quickly, and on the fly. A little nose heavy, but not bad on the bench. I could have, should have been a little more thorough, and am probably lucky that I landed it the first flight upright. It's a good rtf plane, and a fun one, but mine, liked to go up and left like a rocket on the initial flights.

Fly4Fly

Yes, on mine the rudder wouldn't center even with max trim. It required the clevvise on the pushrod to be adjusted about 1 mm.

jetmech05

From the way it sounds I'd suspect the transmitter. Due to reversing controls. If the battery was low or switch intermittent you'd have control and then no control.

Fly4Fly

I agree with you and your speculation leads to a similar conclusion as Tom.

If the tx is defective , I am hoping I could at least exchange that for a non defective one. The plane, since already flown I understand there is nothing other than salvage that can be done.
I will test the transmitter in the coming weeks and let you guys know if I learn anything.

Thanks again

Fly4Fly

But remember, from Everything I have learned here and at the club. Make no compromise and proper preparedness are key to enjoying this hobby.