Unexpected motor glitches (speed up) with Tri Hex and Octo APM 2 & APM 2.5 using 2.73

It seems since going to 2.7 and up to 2.73 I am having uncontrollable glitches with the motors. I think I have isolated everything, no bullet connectors, checked the amperage draw of the 880 motors to see if bearings could be the problem.
I have 2 units, TriHex & Octo with 1 inch carbon fiber tubing for the arms, exhibiting the same glitches, I don't know what's causing it. This morning I flew the TriHex for about 10 seconds and about 5 feet high and suddenly it rolled completely over upside down all within less than a second and broke 5 props, anybody else having this problem or a solution. I'm not flying anymore until I have a fix.....I see 2.74 is in the works but don't see anything that would fix this....Don

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Don - Once logs are downloaded, this is where they are on the PC that was connected..

C:\Program Files\APM Planner\logs

The flashlogs show up as *.log documents.For example: 2012-08-10 22-09 18.log

Enabling the features Jason mentions would provide, on the next flight (I think), a recording of the drive to each motor ESC. In default mode, only the throttle in / throttle out shows up.


Thanks Doug,
I have never had that problem, my problem has always been where one or more of the motors will just give a very quick burst of RPM, enough to hear and see the copter tilt abruptly, usually only last for 1/4 of a second.
I have not figured out how to enable the Motors & Raw for the data flash logs, thanks for responding....Don

As I mentioned, it was hiding in plain view...


This is after getting a connection established with the Terminal tab.

At the "Arducopter 2.x " prompt, type 'logs' (and, of course, press Enter)

You then should have a 'Log' prompt.

Then type 'enable motors' (press Enter).

The response abobe is shown displaying all the logs enabled for the flashram.

Then type 'enable raw' (press Enter)

ditto showing all the logs enabled.




Nvrmnd Jasonshort - See post following. It still would be nice to have a command chart of the CLI. Yes, it could change with the nex release but at least once one was made, it only needs to be updated.


I noticed the same issue. Didn't matter if it was on he bench or I was trying to get off the ground. The rpm would spike for a second and then return to normal.
I didn't have the spike in my last test but broke all the props, my stupid mistake.
The only changes I made was fixing the props so they were tight on the shaft and changes the servo cables from the RX to the APM. Shortened the cables to a few inches.
Can you the spike on the bench?

Have been following with interest as I suddenly had the same problem, very random spikes, in all 3 axis's.

Checking the .log file I found the spikes on the _in channels, and hooking a PWM meter to the Rx output revealed random spikes on the channels.

Changing the Rx had no effect, so I looked at the Tx, which is a Futaba 9CHAP with a FASST module.

Luckily I have another identical Tx and swapping the two solved the problem. The spikes were being generated by an intermittent in the Tx.

Just thought I would broaden the field of discussion as its not a fault I would have suspected, and my focus was purely on the Hexa.

Wow, I never thought of that as I have a Futaba 12FGH, however, not sure I understand the checks that Jason had me do, but my glitches on my Hex went away, have not tried the TriHex yet as I did the same checks with it, that one really had a bad case of glitches. Will get the nerve to try it in a day or two. Need to make sure I have plenty of spare props.....Don
I never see the spike on the bench, however I don't have the props on so there is not any load on the system....Don

sure. BTW, you can type help to dump a command list at any time.


Hi, I have the same problem! I flew with my tri for about 10 minutes with no problem and suddenly the motor turn on full speed and it flipped over and buried into the ground. I didn't read out the log yet but I really don't know what happened. I've got no bullet connectors (i've soldered everything). My tri is resting in peace and I've started to build a quad right now. I'm also not flying anymore before someone can tell me what's the problem. Letting a full carbon tri and quad crash again costs to much money for me. I have the APM 2.5 and used the 2.73 firmware for the tri. Please help

Hi Jason,
Just wondering if dumping the logs had anything to do with my Octo flying better. Flew four 10 minute flights yesterday, but not sure if dumping the logs had anything to do with it. I have not tried my TriHex yet as I did the same with the logs on it. The TriHex had a much worse problem. It seems as all of these glitches start out very slight and get progressively worse with more flights, thanks....Don
Jason, after about 5 flights the glitches are back. It seems like others are having problems as well, hope someone can figure this out. The one good thing is we are keeping the prop people in business, thanks.....Don

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