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Oct 24, 2016, 10:20 AM
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FRSKY/ACCST Failure, crash, rant, questions....


As the title suggests, my Super Sportster EP crashed this weekend. It was my second flight of the afternoon, fresh battery (maybe 2 minutes in?), within visual range, and suddenly my Taranis says "RSSI critical; telemetry lost". Down she went. It happened at a long established flying club. FRSKY X4R receiver, transplanted from a plane that had dozens of flights, no hard crashes.

I'm pretty new to this, been flying about a year. I was under the assumption that ACCST was the most rock-solid protocol available. I've seen 'telemetry lost' before, but only when the Tx was right next to the Rx, which I believe is pretty normal.

I guess I'm mostly venting, but I'm also looking for any thoughts or advice others might have? Anyone else had problems with this particular receiver or protocol? Should I trust that receiver again? (BTW, post-crash I plugged the battery back in and everything worked fine...._) I'm only out about $100, I can't imagine how I'd feel if this happened in a multi-thousand dollar plane.

One interesting coincident; my buddy's next flight also resulted in a crash. I don't know if he pinpointed the problem or not (Futaba/FRSKY TX/RX combo) buy he was complaining about the plane not responding to input, although not entirely, just intermittently. Anybody else have issues on Saturday afternoon, northern CO?

Anyways, thanks for listening.
Last edited by ThirdR8Pilot; Oct 24, 2016 at 05:15 PM.
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Oct 24, 2016, 11:32 AM
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Made in Austria's Avatar
I wouldn't be so quick in blaming Frsky, especially since you are still new to this. Built quality of your model, unreliable power supply to receiver (loose connections, etc.), antenna mounted wrong/ bad location, interference, etc. I'd perform a range check on the ground with the TX in range check mode next time. A range check can safe you a lot of money and frustration.
Last edited by Made in Austria; Oct 24, 2016 at 11:39 AM.
Oct 24, 2016, 02:54 PM
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Thread OP
I'd believe interference. That's the type of issue I'm interested in learning about / discussing. I've never done a range check before, but I've never had an issue before, and I certainly wasn't out of visual range (which I thought was kinda the limit?). I will look into that procedure though.

As for the rest of the issues you listed, that plane had over 50 flights on it, including one successful flight 10 minutes before mayday. Loose connection could be a possibility, I will verify all of those when I strip all the parts out of it.

Thanks.
Oct 24, 2016, 04:04 PM
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TigerOC's Avatar
From what you have described everything points to loss of electric supply to the Rx. Could be a loose lead or a fault in the ESC.
In any situation like this you should check as much as possible at the crash site before touching anything. If you had a flight log running it could give you an idea of any supply problems to the Rx during the flight.
Oct 24, 2016, 04:38 PM
Balsa addiction since age 3
ScottSails's Avatar
As TigerOC pointed out - IF you were logging the RSSI and voltage, it would be greatly helpful. It will store the info in your transmitter and you can then evaluate better what happened.
If you have not done a range check, I strongly recommend you do so. You say no hard crashes - but if the receiver antenna popped free - it could be intermittent which could cause what you have seen....(just a guess but it really does sound like an electrical problem)

PS - I have been flying FrSky Taranis for 2 seasons, FrSky in general for 4 seasons - no issues.

Scott

Here is a picture that should be similar to yours
https://www.rcgroups.com/forums/show...19&postcount=7
Last edited by ScottSails; Oct 24, 2016 at 05:58 PM.
Oct 24, 2016, 05:06 PM
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Thread OP
I'm going to guess that the flight logging is something that I need to turn on? If so, then no logs. I'll definitely look into that for future use, great suggestion, thanks!

I believe all of the wiring stayed together on recovery of the wreckage, so I'll try to double check connections, but as I posted above everything came back on and worked fine when I plugged the battery back in (obviously couldn't check the motor, but that's down stream and shouldn't be relevant here).

You're saying that the antenna may have come loose from the Rx? I think I can slide the cardboard off the Rx so I should be able to check that.

I think I'll have to move the ESC and Rx into a cheaper plane (foam wing probably) for now. Not sure I can trust either unless I can find the problem. I do agree that loss of power to the Rx seems most likely.

Thanks!
Last edited by ThirdR8Pilot; Oct 24, 2016 at 05:15 PM.
Oct 24, 2016, 06:15 PM
Balsa addiction since age 3
ScottSails's Avatar
Quote:
Originally Posted by ThirdR8Pilot View Post
I'm going to guess that the flight logging is something that I need to turn on? If so, then no logs. I'll definitely look into that for future use, great suggestion, thanks!

I believe all of the wiring stayed together on recovery of the wreckage, so I'll try to double check connections, but as I posted above everything came back on and worked fine when I plugged the battery back in (obviously couldn't check the motor, but that's down stream and shouldn't be relevant here).

You're saying that the antenna may have come loose from the Rx? I think I can slide the cardboard off the Rx so I should be able to check that.

I think I'll have to move the ESC and Rx into a cheaper plane (foam wing probably) for now. Not sure I can trust either unless I can find the problem. I do agree that loss of power to the Rx seems most likely.

Thanks!
Yes, it does need to be turned on....
Oct 24, 2016, 07:08 PM
Sagitta Fanboy
Quote:
Originally Posted by TigerOC View Post
From what you have described everything points to loss of electric supply to the Rx. Could be a loose lead or a fault in the ESC.
In any situation like this you should check as much as possible at the crash site before touching anything. If you had a flight log running it could give you an idea of any supply problems to the Rx during the flight.
A pure Electrical loss should have just resulted in 'Telemetry Lost' without the RSSI critical callout.

RSSI critical, followed by telemetry lost sounds more like either a burst of RFI, or more likely a servo or ESC failure. Something cause a signal hit right before the RX dropped offline.

To me, this sounds like an ESC failure as the likeliest option. Since the ESC is already generating a high frequency output and is also likely the origin of the power for the RX, if it failed it could cause a moment of interference before the RX lost power.

Note, if it was external interference, I'd expect a reconnect pretty quickly, RSSI critical does not indicate loss of control link necessarily (for example my Radian Pro will give me an RSSI Critical chirp in one particular orientation when the motor is on, due to my antenna install, which is unfortunately dictated by compartment layout. does it once per flight at the top of the climb and I never lose control as it just hits 48-49, enough to prompt the chirp, not enough to lose the control signal).
Oct 24, 2016, 07:56 PM
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Thread OP
Quote:
Originally Posted by mawz View Post
A pure Electrical loss should have just resulted in 'Telemetry Lost' without the RSSI critical callout.

RSSI critical, followed by telemetry lost sounds more like either a burst of RFI, or more likely a servo or ESC failure. Something cause a signal hit right before the RX dropped offline.
I'm not so sure about this. Every time I disconnect the battery from a plane, my radio says "RSSI critical, telemetry lost".
Oct 24, 2016, 09:27 PM
Sagitta Fanboy
Quote:
Originally Posted by ThirdR8Pilot View Post
I'm not so sure about this. Every time I disconnect the battery from a plane, my radio says "RSSI critical, telemetry lost".
That's interesting, all of mine say 'Telemetry Lost' without the RSSI critical callout. That's across 4 birds running a D4R-II, X4R-SB, X6R and X8R.

Possibly a version issue then, I'm running 2.1.9

If all yours say that when powering off, I'd bet on power loss at the RX, could readily be a cabling issue.
Oct 25, 2016, 02:45 AM
Proud to eat Kraut ;-)
Julez's Avatar
What were your failsafe settings, and did they engage after control was lost?
Oct 25, 2016, 03:55 AM
Registered User
TigerOC's Avatar
I do logging on all my models and with electric powered models it is initiated when I arm the motor through a switch.

On new installations the logs of the RSSI are carefully monitored with special reference to the attitude of the model relative to me. I carry out a defined flight pattern to determine whether the antenna in the model are ideally placed. Once I am satisfied with the initial flights the logs are gone through on a cursory basis.

The voltage pattern out of an ESC is important because you get early warnings of failure that you need to be aware of.

I have been using the Taranis for 2 years now and have never ever received an RSSI warning in the air. That's after hundreds of flights. I fly gliders as well, at quite long range as well going up to 1500 feet.

Rob
Oct 25, 2016, 04:22 AM
Registered User
As sherlock said, after you eliminate all the above reasons, whatever remains, no matter how improbable, must be the truth... i.e. the receiver, because is an X series receiver
Is not the first lockup reported for these receiver types.
Oct 25, 2016, 04:43 AM
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TigerOC's Avatar
Quote:
Originally Posted by renatoa View Post
As sherlock said, after you eliminate all the above reasons, whatever remains, no matter how improbable, must be the truth... i.e. the receiver, because is an X series receiver
Is not the first lockup reported for these receiver types.
This is a really ignorant comment with the details given in the initial post. There have been problems specific to the iteration 1 version of EU LBT firmware but that does not apply in this instance.
Oct 25, 2016, 05:03 AM
Registered User
Please read your post again when you reach at least my post count related to Frsky support alone... then you are free to blush.


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