F550 With Naza Dropped From the Sky!!!

[BigPete]

I have been flying my F550 with Naza M v2 for over a month now. It's paired with a Spektrum receiver. Yesterday I was flying FPV and it just dropped like a rock from the sky at about 150ft altitude!! And only about 150ft distance from me. Broken to pieces!! Ugh!!! What the heck happened? Not sure. My failsafe is 100% working, many many times with Tx signal loss. At first I thought my battery might have come disconnected the connection was not the tightest, but not falling out loose either. Then I remember I saw the F550 falling and tumbling though my FPV goggles. So if it was a battery connection failure then my vtx would have cut off immediately and I would not have seen the falling/tumbling though my goggles.

I did recently change my vtx vRx to 900mhz from 5.8ghz. Could that some how froze the Naza controls? I just don't understand it.

Any suggestions to what happened? Anything you guys suggestion I look at for possible signs of failure? I really want to find out before I put another aircraft in the air so this won't happen again.

 

[dmetz]

Hi BigPete, Very sorry to hear about your mishap. I know how frustrating and disappointing this can be. When I first flew my MR and albeit, without sufficient battery voltage monitoring, my Tarot 650 quad did a similar thing though fortunately during a test flight and very close to the ground so no real damage. Can you be sure your voltage did not drop to a level insufficient for your FC or ESC's but still perhaps enough juice to power that transmitter?

What kind(s) of voltage monitoring do you have in place?

 

[JoeBob]

How much juice was left in the battery? (Assuming it survived enough to put it on a meter...)

My 550 and Spektrum did the same to me a few months back, but it was a hard descent ignoring my radio inputs.

 

[OneStopRC]

Pete has been having issues with GPS lock on that very F550, but has since moved channels to one that is not interfering. I don't or can't see it being interference, for it to shut down mid flight would indicate a failure with the Naza. How was the connections to the naza, did you notice any strange things during your flight and what voltage was left in your battery?

 

[BigPete]

Thanks for response guys. Ok you have me thinking, actually this flight was the first flight of a used 4s 35c battery i just bought. This is the first time i flew the F500 on 4s. Previous was 3s 5000mah. I have the E300 ESCs and DJI 2212/920kv motors so 4s should not be a problem correct? Batt was fully charged. I have iOSD to show my voltage it was @ 16.5v at launch before flight. I did not look at the voltage under stress. The batt was a little dented, but survived. It showed 3.95v per cell after crash. Is it possible that the battery is bad and drops voltage under load, and then returns voltage when not stressed?

I double checked all power and servo connections after the crash and everything looked visually ok.

Only other change to the aircraft with this flight is i placed a IBcrazy Cloverleaf antenna on the vtx. At least that survived the crash.

Only thing weird i noticed Onestoprc was that the GPS signals were lost for only about 5 seconds, then came back. That has not happened since I changed vtx channels. After that i believe i flew in Attitude mode. Cant remember if i switched back to gps mode before crash.

I have an expensive TBS Discovery with a Naza v2 in it also, now im scared to fly it. If something would happen with that much money in the air..... That would make me sick!

 

[haleymon]

Thanks for response guys. Ok you have me thinking, actually this flight was the first flight of a used 4s 35c battery i just bought. This is the first time i flew the F500 on 4s. Previous was 3s 5000mah. I have the E300 ESCs and DJI 2212/920kv motors so 4s should not be a problem correct? Batt was fully charged. I have iOSD to show my voltage it was @ 16.5v at launch before flight. I did not look at the voltage under stress. The batt was a little dented, but survived. It showed 3.95v per cell after crash. Is it possible that the battery is bad and drops voltage under load, and then returns voltage when not stressed?

I double checked all power and servo connections after the crash and everything looked visually ok.

Only other change to the aircraft with this flight is i placed a IBcrazy Cloverleaf antenna on the vtx. At least that survived the crash.

Only thing weird i noticed Onestoprc was that the GPS signals were lost for only about 5 seconds, then came back. That has not happened since I changed vtx channels. After that i believe i flew in Attitude mode. Cant remember if i switched back to gps mode before crash.

I have an expensive TBS Discovery with a Naza v2 in it also, now im scared to fly it. If something would happen with that much money in the air..... That would make me sick!

You said you went from a 3 cell to a 4 cell... i dont remember if you HAVE to do this or not... but... did you reprogram the Naza for 4 cell?

Dave

 

[soler]

You said you went from a 3 cell to a 4 cell... i dont remember if you HAVE to do this or not... but... did you reprogram the Naza for 4 cell?

Dave

Reprogramming the Naza will effect the low battery alarms but should not make it drop out of the sky with 3.95V per cell. I would put a Lipo alarm on the battery to see if it is going low voltage when you climb.

 

[JoeBob]

IS NAZA Voltage protection on or off? (Advanced/Voltage page.)

 

[OneStopRC]

Going in or out of GPS mode would not make it fall out of the sky, even if the Sats was missing, it still would not fall. It might fly off in a weird direction but certainly would not fall.

Nazas can be strange at times, I have only ever had one issue with my Naza and that was from a start up, it kept flipping on me. I unplugged the battery and 10 seconds later I plugged it back in and all was good.

Was this the only pack you flew with on this day? close to some sort of radio tower? do you have your failsafes setup for 50% throttle and so forth? are you using immediate cutoff in the assistant?

 

[BigPete]

Sorry guys, I have been out of town. I was finally was able to do some testing.

IS NAZA Voltage protection on or off? (Advanced/Voltage page.)

Protection was on, but batt was at 3.95V per cell after crash.

Going in or out of GPS mode would not make it fall out of the sky, even if the Sats was missing, it still would not fall. It might fly off in a weird direction but certainly would not fall.

Nazas can be strange at times, I have only ever had one issue with my Naza and that was from a start up, it kept flipping on me. I unplugged the battery and 10 seconds later I plugged it back in and all was good.

Was this the only pack you flew with on this day? close to some sort of radio tower? do you have your failsafes setup for 50% throttle and so forth? are you using immediate cutoff in the assistant?

Yes OneStopRC, that was the only pack i flew that day. No radio tower in any visual range. But less than a mile from a hospital and 10 miles from a small airport. Not positive of Failsafe throttle settings, but tested failsafe many times, and even when out of radio range. Failsafe always worked flawlessly with no loss of altitude probably 10-15 times with that setup.
Good idea about immediate cutoff. This could be a possibility. Intelligent cutoff was off and settings were on immediate cutoff. Could i have brought the throttle too low and the motors just cut off. That is a good possibility. I was descending for a landing in the time of the cutoff. I would say this is a 90% possibility.


I installed the Naza v2 on a completely different platform. A Flip FPV quad with different ESCs and motors. Checked throttle rate around cutoff level, yup it dropped. Testing on grass at low altitude so no damage. Turned settings to intelligent cutoff, so no more of that.
BUT THEN with testing the quad it keeps rolling over and crashing. I noticed it kept roll flipping to one certain side and angled towards the front every time. And most of the time it would happen when aggressive throttle boosts. Took apart wiring covers on the side the quad whee it kept flipping to and saw that one of the solder connections came loose. Re-soldered and no more rolling flips.

But i still believe its a 90% chance my primary crash was due to immediate throttle cutoff, 10% some freak radio interference. Just be very careful with your surroundings guys. You never know when a freak accident like this could happen.

 

[tstanfordjr]

I am new to this hobby and purchased a Phantom 2 and have had it for maybe a month. I just switched from GPS mode to Naza Mode and seems to fly as described by DJI but after reading this thread I am concerned about this line in the thread

"Intelligent cutoff was off and settings were on immediate cutoff" Im not sure what that means and dont want to make the same mistake mine is stock setting except for switching from GPS to Naza Mode

Thank You for your feedback

 

[OneStopRC]

Immediate cut off, when you drop throttle to below 10% or down to zero, the motors shut off instantly and require the start sequence to start them again, by this time it could all be over. Leave it on intelligent cutoff, if you go below the 10% it will give you a few seconds before shutting the motors down.

 

[fredor]

I reply more for the benefit of others but I would say you have already realised that you brought the throttle down too far , I have been using the same NAZA unit for over two years without problem, from the unit that is