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PostPosted: Wed 30. Oct 2019 21:36:45 
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Joined: Thu 18. Jul 2019 15:13:20
Posts: 8
I had an unusual event today and would love to hear some advice.

I was flying my Blade Fusion 270 with the following setup:

Spirit Red
Frsky R-XSR receiver
KST "Daviga" 213 servos on the cyclic
HS3060 rear tail servo
Stock motor
Stock ESC/BEC (running BLHeli I think). ESC is handling the governer with default settings.

This was my 50th flight with the Blade 270 and this setup. No flight problems up to this point.

The only thing about the day that was unusual was it was a bit colder than usual at around 2C.

I flew 3 batteries with no issues. 4 minutes into the 4th battery, I was doing a simple upright circuit about one meter off the ground with the heli maybe 25 yards from where I was standing. The motor spooled down with no explanation. I seemed to still have control of the servos as I was able to do an autorotation landing and did not damage the heli. The battery pack on the ground were 3.9V on each cell, unloaded of course.

After it was on the ground a second or two, the motor decided to spool itself back up but I hit throttle cut to stop it.

I then checked the spirit logs using a the LUA-based logviewer app to see if I maybe had a failsafe.

The log was strange, "normal" messages about halfway through the flight, then the log showed lots of problems, some can't be real. Basically it scrolled each one of these messages in every slot:

Backup Oscillator is used
Cyclic Ring Activated
Rudder Limit Reached
Vibration Level is very high
Main Loop Hang Occured
Receiver Signal Lost
Power Voltage is low
Governor was Engaged (???)

all of these for at least half of the log data... I have to believe that this number of problems could not be real for half the flight so the logging data seems to be corrupted.

As an aside - I'll mention that sometimes the spirit will "double initialize" itself on battery plug-in where it starts the normal beeping and calibration process, but something makes it start over before it twitches the servos. That didn't happen this time but it happens somewhat often - I'm not sure if it's related.

Moving forward, I plan on:

- reviewing opentx logs, especially receiver voltage
- Check firmware on the unit. Update if needed.
- Take off the blades. Do a vibration test.
- Let it run on the ground with no blades and check for problems in the logs
- do a range test
- Check everything mechanically
- Assuming no problem are found, fly a couple of batteries at a low hover, then just simple circuits, checking logs after each flight

Any other thoughts or suggestions?


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PostPosted: Thu 31. Oct 2019 3:16:21 
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Joined: Thu 18. Jul 2019 15:13:20
Posts: 8
I looked at more data and ran some tests.

The opentx log is attached. The green spike at the end shows where I applied collective to autorotate.

The voltage to the receiver (yellow line) is solid throughout the flight.

RSSI (Red line) looks fine.

Fuel % (magenta line) has an interesting jump around the problem time. I have no idea what this telemetry value is trying to tell me. I think the spirit is generating it?

---

Other things I did:

Range check. I turned on "range test" mode walked out to 50 meters with no issues seen at any point.

Firmware check. I was at 2.6.3 I updated to 2.6.4 today for good measure.

Vibration check. I ran the spirit vibration tool with blades off. Everything looks fine, vibrations are low. and spirit software shows "OK". I can post images if we want to look at this more.

Battery internal resistance check. It looks fine at 12 milliohms and in line with my other batteries.

I took the blades off and let the copter spin for 15 minutes using the same battery I used during the failure. No issues seen. I checked the spirit logs, "normal" for the most part with some "rudder limit" reached when I move the rudder around. Nothing concerning. The battery ended at 3.9v per cell, evenly matched.

---

One thing about my earlier post is that the strange logging message were actually for the first half of the flight - they cleaned up for the second half. But now I'm not 100% sure if the second half was clean of problems so it is possible that a split-second failsafe occurred - I don't have the data to prove or disprove it.

---

So unless someone has a suggestion, I think the next step will be hover and slow circuits to regain confidence and hopefully limit damage if the motor spins down again.


Attachments:
20191031_Fusion_Motor_Fail_Flight.png
20191031_Fusion_Motor_Fail_Flight.png [ 213.33 KiB | Viewed 114 times ]
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PostPosted: Fri 01. Nov 2019 13:36:06 
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Joined: Mon 29. Apr 2013 16:06:44
Posts: 9036
Hello,

thank you for very detailed description.

What was displayed at the flight log is unfortunately very likely wrong. But I am unable to tell you why this happened. It is possible that it was stored for a longer time there from a previous testing.

Double initialization is really not looking well. It is related to your BEC maybe. I recommend to perform BEC test for at least 2 times.

Maybe you saw a different kind of initialization caused by engaged Rescue mode. If rescue is engaged during powerup then it will show this notification. You can verify it if this was the case.

If you were able to control the model even during this event then I am convinced the unit operated properly. The ESC might turn off due to overheat or possibly due to a moisture that could develop if it is heating up. Unforuntately I fear the problem will occur again. So I recommend to perform testing on the ground with a similar temperature condition at the moment.

Starting motor without blades for several minutes during similar temperature should reveal more.

_________________
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PostPosted: Fri 01. Nov 2019 16:19:35 
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Joined: Thu 18. Jul 2019 15:13:20
Posts: 8
Thank you for the reply.

I did 4 flights yesterday and no problems. I checked the spirit logs after each flight and saw only "Good Health Message".

I think it's possible I had a very brief failsafe during the failure. Unfortunately, the early messages in the log captured my attention and I didn't look close enough at the logs that would have mattered near the end of the flight. Briefly losing signal is a known thing at our field that seems to effect everyone now and then. We think there could be an RF noise source somewhere nearby.

Also, if I continue to see the double-initialize issue, I'll replace the stock ESC with something different.


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PostPosted: Mon 04. Nov 2019 19:45:57 
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Joined: Thu 18. Jul 2019 15:13:20
Posts: 8
4 more flights today and they seemed perfect.

I checked the logs on the 3rd and 4th flight. On the 3rd flight, the logs were corrupted in a manner that looks just like post #1

- A mix of many messages for 180s or so
- "Receiver signal lost" 2 times
- "Good health message" after that

again, no detectable problems in the air. If I didn't look at the logs, I would have assumed they were clean.

The 4th flight logged as "Good health message" throughout.

Not sure if this is a bug or a problem with my specific unit. I'll try and take pics the next time it happens.


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PostPosted: Mon 04. Nov 2019 19:58:39 
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Joined: Mon 29. Apr 2013 16:06:44
Posts: 9036
Hello,

Receiver signal lost should not occur normally if your radio was always on.
If yes, then this mean that failsafe was being triggered for a short period of time because it is loosing signal.
Either between radio/receiver or between receiver and unit.

So it is rather matter of time when problem will occur again.
Because of your logs it look rather as problem between receiver and Spirit unit.

Please verify that cables are not near boom (possible static discharges) and that belt tension is good.

_________________
Spirit System developer


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