Deucalion Posted at 4-27 07:16
For every user that doesn't store their drone, dozens do, and neither group had more or less prop issues. And for every user who cut up their case, hundreds didn't, and again, neither group had more or less prop issues.

I had issues with my props. I also drink milk. So, I replaced my props and stopped drinking milk. Now no issues. Ergo, drinking milk causes prop issues.

Non Sequitur

Deucalion Posted at 4-27 07:16
For every user that doesn't store their drone, dozens do, and neither group had more or less prop issues. And for every user who cut up their case, hundreds didn't, and again, neither group had more or less prop issues.

"For every user that doesn't store their drone, dozens do"

Yep...fully agree...and?

...apart bad props and numerous updates?

...do some minis have issues with rear-arms?

djiuser_xiKkRfWbTNKe Posted at 4-27 07:17
The file looks like it's been analysed using CsvView - guide here - https://mavicpilots.com/threads/flight-log-retrieval-and-analysis-guide.78627/

Mine looks like it has had the back left issue since its very first flight based on the logs, strange the error warning has gone away

Thx

Deucalion Posted at 4-27 07:20
I had issues with my props. I also drink milk. So, I replaced my props and stopped drinking milk. Now no issues. Ergo, drinking milk causes prop issues.

Non Sequitur

Me think this is a factory issue with a certain batch of minis and rear legs.

fans1cafe718 Posted at 4-27 07:20
Thx

I've checked the logs a bit more, the error looks like it 'triggers' when the prop (back left) hits more than 16.4k rpm ( 17k max?)

My other flights don't seem to have reached this level

fans1cafe718 Posted at 4-27 07:15
...and your theory?

My theory, actually the work was done by a couple other users here, is simple.

Some of the props were not up to snuff from the factory.

Prior to this update, that caused a handful of uncommanded descents and some users noticed ESC error in their logs, even though they didn't see them on the screen while flying and didn't experience an uncommanded descent.

That is the crux of it. Then this FW update happened, or I should say didn't happen, and lots of users were getting notified that their props were bad, but then when they hooked up to DJI Assistant, it said the firmware update was incomplete, and when they fixed it, most didn't get any errors. Those who still did get errors, replaced the said props, and then they didn't get any errors. A few remain with errors.

fans1cafe718 Posted at 4-27 07:26
Me think this is a factory issue with a certain batch of minis and rear legs.

Then why would replacing a prop fix it? I would agree if users are replacing rear legs.

Deucalion Posted at 4-27 07:33
The why would replacing a prop fix it? I would agree if users are replacing rear legs.

...yes...but a slightly outta spec rear leg would induce more props wear and tear...

fans1cafe718 Posted at 4-27 07:36
...yes...but a slightly outta spec rear leg would induce more props wear and tear...

What wear and tear? Maybe you haven't been following this that long, but there hasn't been any wear and tear. In a wear and tear situation, users would progress from having no issues or messages to having issues and messages. There hasn't been any progression like that. Some users with the issue hadn't even had the drone that long. While the rest of us flying the crap out of ours didn't know what they were talking about. Then these storage case theories started. Yet the rest of us with storage cases and flying the crap out of our drones didn't understand what that fuss was about either.

Some drones had prop issues from the factory. The rest did not. This bungled FW update just obfuscated everything.

Deucalion Posted at 4-27 07:41
What wear and tear? Maybe you haven't been following this that long, but there hasn't been any wear and tear. In a wear and tear situation, users would progress from having no issues or messages to having issues and messages. There hasn't been any progression like that. Some users with the issue hadn't even had the drone that long. While the rest of us flying the crap out of ours didn't know what they were talking about. Then these storage case theories started. Yet the rest of us with storage cases and flying the crap out of our drones didn't understand what that fuss was about either.

Some drones had prop issues from the factory. The rest did not. This bungled FW update just obfuscated everything.

Agree. Straight outta factory and porked.

ABeardedItalian Posted at 4-26 21:28
For the MM, DJI requires you change props in pairs, and I believe the first letter-number combo is what identifies a "matched set". Please check if the markings on each half-prop matches the other half.

What I had posted to begin with....

Understood, you didn't explicitly say that the 2 half-props on each corner had matching markings, so I asked you to confirm that.

I think the fact that your opposite motors have identical markings is just a coincidence, probably  because when your MM was assembled, they got all CW and CCW props from the same bins. I have original props on my MM, and they also match "diagonally", but what's really important (and DJI requires) is for the 2 half-props on each motor to match.

grahamjohnson10 Posted at 4-27 06:53
There have been many reports of uncommanded descent of the drone due to rear propeller failure as well as the new error message in .500 firmware of a motor speed error.

I was flying yesterday when I received the motor speed error caused by deformed  propellers on the rear left motor.

Excellent analysis, it fully confirms that the issue is with the props, which lose pitch causing high RPMs. The new firmware simply throws an alert when it sees a motor spinning substantially more than the others, and instructs the pilot to replace the props on that specific corner. It's very simple, and very smart. As I said in previous post, it's the same principle that some TPMS (Tire Pressure Monitoring Systems) use, relying on ABS sensor to detect wheels that are suddenly rotating faster than the others (because of a flat).

Now we really need to see if this will prevent uncommanded descents, but I think it will, everything makes a lot of sense.

To those who say the error "goes away" with a restart: it might simply be that your props are near the error threshold, and external conditions/factors might push it above or below that. Refresh your firmware via DJI Assistant to make sure everything is fine on that front, then if you see an error, even intermittent, replace the props.

120ccpm Posted at 4-27 08:05
Excellent analysis, it fully confirms that the issue is with the props, which lose pitch causing high RPMs. The new firmware simply throws an alert when it sees a motor spinning substantially more than the others, and instructs the pilot to replace the props on that specific corner. It's very simple, and very smart. As I said in previous post, it's the same principle that some TPMS (Tire Pressure Monitoring Systems) use, relying on ABS sensor to detect wheels that are suddenly rotating faster than the others (because of a flat).

Now we really need to see if this will prevent uncommanded descents, but I think it will, everything makes a lot of sense.

So...hopefully, it's just a bad props problem.

I don't have problems but I have brand new props in stock that I got with my Fly-More-Combo and lots more brand new props in-stock straight for DJI.

If props problem, hope DJI will replace no-charge.

fans1cafe718 Posted at 4-27 08:12
So...hopefully, it's just a bad props problem.

I don't have problems but I have brand new props in stock that I got with my Fly-More-Combo and lots more brand new props in-stock straight for DJI.

I think it's pretty clear that the props are the problem. What causes that (improper storage, bad batches, un-matching pairs) is still to be confirmed, I don't think anyone has a definite answer.

120ccpm Posted at 4-27 08:15
I think it's pretty clear that the props are the problem. What causes that (improper storage, bad batches, un-matching pairs) is still to be confirmed, I don't think anyone has a definite answer.

Hope your are right about the props...that would be a welcome relief.

But best, would be a porked firmware/update combo...

Myself am worried that all the extra props I have might have some fubars..

We'll see.

120ccpm Posted at 4-27 08:15
I think it's pretty clear that the props are the problem. What causes that (improper storage, bad batches, un-matching pairs) is still to be confirmed, I don't think anyone has a definite answer.

We know it is not storage, but that is all we know. Unless a 1000 drones in their cases is a lie

grahamjohnson10 Posted at 4-27 06:53
There have been many reports of uncommanded descent of the drone due to rear propeller failure as well as the new error message in .500 firmware of a motor speed error.

I was flying yesterday when I received the motor speed error caused by deformed  propellers on the rear left motor.

Probably the most useful post on this string.  Thank you for publishing data and not hyperbole.

grahamjohnson10 Posted at 4-27 04:42
There is no need for a handheld tachometer lol, why not just analyze the .DAT file like I did.

[view_image]

To independently verify Prop speeds.

Hello fellow pilots. Today I also received the error on the reat left prop, my props where new. My understanding is that an algorithm runs comparisons of rotation speed between the front right-rear left and front left-rear right prop depending on yaw, roll and pitch at that given moment. MM is assymetrical quad copter meaning that the center of gravity is not exactly in the center. Most of the weight is towards the rear. I believe that under certain load you are going to get this error and this is a software error as it allows a very small difference between props of the same set.

YiannosZ Posted at 4-27 09:46
Hello fellow pilots. Today I also received the error on the reat left prop, my props where new. My understanding is that an algorithm runs comparisons of rotation speed between the front right-rear left and front left-rear right prop depending on yaw, roll and pitch at that given moment. MM is assymetrical quad copter meaning that the center of gravity is not exactly in the center. Most of the weight is towards the rear. I believe that under certain load you are going to get this error and this is a software error as somehow they have made the allowance of prop rotation between props on the same set rotation too narrow....

You should first connect the drone to DJI Assistant and make sure that the FW upgrade was complete and successful. For many this fixes the issue. If after that, you still get the error, then you can replace the props and this usually fixes the issue. It isn't about new props. They can be bad straight from the factory. Let us know how it works out.

And again: no comment, no help from DJI or the admistrators for this topic, that is very, very sad.

Newbie Europe Posted at 4-27 10:09
And again: no comment, no help from DJI or the admistrators for this topic, that is very, very sad.

Give them some time, I am sure they are following the forums and they are looking at a correct response

YiannosZ Posted at 4-27 09:46
Hello fellow pilots. Today I also received the error on the reat left prop, my props where new. My understanding is that an algorithm runs comparisons of rotation speed between the front right-rear left and front left-rear right prop depending on yaw, roll and pitch at that given moment. MM is assymetrical quad copter meaning that the center of gravity is not exactly in the center. Most of the weight is towards the rear. I believe that under certain load you are going to get this error and this is a software error as it allows a very small difference between props of the same set.

"MM is asymmetrical quad copter"

Very interesting...so, weight and balance is off naturally??

...and where you get your assumptions?

YiannosZ Posted at 4-27 10:31
Give them some time, I am sure they are following the forums and they are looking at a correct response

I understand that very much, but why is there silence on this topic by DJI or the administrators, otherwise a quick comment comes to every topic, not here, there is silence on this very important topic.

Newbie Europe Posted at 4-27 11:30
I understand that very much, but why is there silence on this topic by DJI or the administrators, otherwise a quick comment comes to every topic, not here, there is silence on this very important topic.

So...I've read about all the mavic minis rear motor/prop issues...but never could replicate it. Until today...

I decided to store my mini in the case overnight (never have) and test fly it today during moderate wind.
Immediately the drone sounded more high pitch than I've ever heard it upon take off...and shortly after I was met with the "beeping esc change props " message.

Here's what I did. I rebooted the drone...and took off again immediately. No whine...no errors. Hmmmm...

Then I packed it back into the case...and then decided to try 1 more flight. As I was preparing to press takeoff...my phone rang and I took it...while pressing takeoff anyway. That's when I noticed something...

When the blades are crossed over one another as if it was just unpacked...there's a clicking noise as centrifugal force un-wraps them...and immediately the high pitch dound returned and stayed for the entire flight.
I tested this several times...either opening the blades manually and letting them be

djiuser_andVRHgynP6r Posted at 4-27 11:41
So...I've read about all the mavic minis rear motor/prop issues...but never could replicate it. Until today...

I decided to store my mini in the case overnight (never have) and test fly it today during moderate wind.

...tested many times?

...and always same results??

You sure?

Newbie Europe Posted at 4-27 11:30
I understand that very much, but why is there silence on this topic by DJI or the administrators, otherwise a quick comment comes to every topic, not here, there is silence on this very important topic.

Well most users are up and flying now. I m not sure what they can say now. Sorry we weren't here during the weekend. If you are still having an issue, I would open a ticket for sure.

fans1cafe718 Posted at 4-27 11:44
...tested many times?

...and always same results??

Several...not many.
Enough to be satisfied that unfurling the props eases the issue.

Bare in mind...never had the issues until today.
Still using props that shipped on mini.

fans1cafe718 Posted at 4-27 11:00
"MM is asymmetrical quad copter"

Very interesting...so, weight and balance is off naturally??

Maybe, why not. Up to 1.0.5, a fly was able to sit on the left rear arm during the flight without causing an error. This is now different.
I think the (new) procedure / function that measures the load of the individual motors and brings an error message, if the imbalance is too great, has trigger points that are too sensitive. This would explain that many people get this message even though they have never had any problems before, neither ESC errors nor uncommanded descents.

120ccpm Posted at 4-27 08:15
I think it's pretty clear that the props are the problem. What causes that (improper storage, bad batches, un-matching pairs) is still to be confirmed, I don't think anyone has a definite answer.

It’s not clear that props are the problem, in fact far from it, it seems now you’re saying that those who had new props on had bad props but those who had props since November, well they’re ok , I think descending craft had a little more to it than props.
Do you really think those who had props stored in their bags could be stored wrong or those who use combo case some can have bad props but others are perfect.

I haven’t read anywhere where someone who replaced props still had a problem with this bad batch you talk about or do you think all bad batch were already on crafts or should we all send our extra props back.

What I read from you is they’re bad props out there on drones and in bags that are bad and if these bad ones are not detected then we will still have these descents, and can you show us how these props go bad from simple storage.
For me I don’t believe the problem with descending craft was or can be merely put down to bad props .

120ccpm Posted at 4-27 08:15
I think it's pretty clear that the props are the problem. What causes that (improper storage, bad batches, un-matching pairs) is still to be confirmed, I don't think anyone has a definite answer.

You’re right and that’s not a definite answer.

jonny007 Posted at 4-27 11:49
Maybe, why not. Up to 1.0.5, a fly was able to sit on the left rear arm during the flight without causing an error. This is now different.
I think the (new) procedure / function that measures the load of the individual motors and brings an error message, if the imbalance is too great, has trigger points that are too sensitive. This would explain that many people get this message even though they have never had any problems before, neither ESC errors nor uncommanded descents.

Actually, not many people are getting this error now AFTER they connect to DJI Assistant and make sure that the firmware update is successful. I was worried that the trigger was too sensitive as well, but the handful of users who still have prop issues after a successful FW update seem on the same order (number) as those getting errors before the FW update. In other words, maybe they do need to replace their props. Those that do seem to fix the issue. That is not to say that the trigger for the prop warning or the previous uncommandered descent is too sensitive, but since it is now back to a handful, maybe the correct course is to just change the props. If after changing the props, this handful is able to fly as freely as the rest of us, then I would say that is a fix.

Deucalion Posted at 4-27 11:56
Actually, not many people are getting this error now AFTER they connect to DJI Assistant and make sure that the firmware update is successful. I was worried that the trigger was too sensitive as well, but the handful of users who still have prop issues after a successful FW update seem on the same order (number) as those getting errors before the FW update. In other words, maybe they do need to replace their props. Those that do seem to fix the issue. That is not to say that the trigger for the prop warning or the previous uncommandered descent is too sensitive, but since it is now back to a handful, maybe the correct course is to just change the props. If after changing the props, this handful is able to fly as freely as the rest of us, then I would say that is a fix.

...agree...let's see how often these "problem users" will have to change their props vs us "no problems" users.

In other words...how often they will get this error.

I still believe it's a factory problem with rear arms...I hope am wrong.

Wow! I've been reading the forums off and on for a couple of years before pulling the trigger. (a little over cautious?)  Anyway in my travels I've learned more than I can remember. (let's get to the point) As we all know or should know no one ingredient makes a stew. One certain system failure can bring down the biggest Bld, airplane, etc. The .Dat charts blew me away. Good job Gramjohnson, you've shed new light on a forum that was getting no where.

Does anyone own a boat or an airplane? The pitch of the prop is everything. Older two cycle motors liked 6200 rpm (peak horsepower that didn't destroy the motor) A lower pitch the boat accelerates quicker, air planes climb faster but neither goes its potential for speed. Now electric motors are different from gas. There is a pitch that works best for longevity (flying time) If I wouldn't have seen the second Dat. chart I would have thought that the left rear corner was heavy and the prop had to spin faster to hold up the corner. If you put the old and new props under a microscope you probably can't see a difference. Changing the props definitely brought the RPMs in line don't you think.

Now then things go awry with a new firmware up grade. In a batch of props that were spinning to fast causing occasional  uncommanded descents have different parameters to alert you to a problem that's been border line all along.  Now what happens if they eliminate the warning or the make it land? I don't know. Does the motor have a catastrophic failure an drop the drone on people below?

Maybe the rear corner IS heavier and needs a higher pitched prop. Experiment tie lead sinkers under the right front motor pivoting the drone on the left front and right rear (like a three legged chair) making them work harder but taking weight off the left rear. Now let's see if it throws flags. Let's see what happens to the Dat. charts just by shifting some weight off the left rear. Maybe it's nothing more than bad props and stricter parameters. But I think the Dat. charts shed a whole new light on the problem.   

SLiWooDy Posted at 4-27 09:40
https://youtu.be/edTWQcMJ-3M

Guy mentions not leaving drone in directly Sunlight as it will most certainly warp the props.

Wonder if while flying, the added stress on blades coupled to Sunlight and warm to hot ambient air temperature could result in warped props?

A few people have dismissed the latest FW motor / prop warnings as FW bug, and problem going away with re-flash using Assistant-2.  At same time others have seen warnings go away after replacing prop indicated by latest MM firmware.

Believe one person felt warnings stopped after merely power-cycling MM.   Then there is evidence from motor RPMs from .DAT file which showed one motor spinning faster than other four, and once prop was replaced on that motor, the RPMs of motor came down in line with other motors.

A person posted a scope video showing MM's props were not getting bent when placed in case.  Recent video warns about carefully positioning props so they are not warped by case.   Wondering if there are cases with different contours, or perhaps some cases were made with defect in contour; explaining why some people have problems while others don't.

JB 9 Posted at 4-27 13:53
Wow! I've been reading the forums off and on for a couple of years before pulling the trigger. (a little over cautious?)  Anyway in my travels I've learned more than I can remember. (let's get to the point) As we all know or should know no one ingredient makes a stew. One certain system failure can bring down the biggest Bld, airplane, etc. The .Dat charts blew me away. Good job Gramjohnson, you've shed new light on a forum that was getting no where.

Does anyone own a boat or an airplane? The pitch of the prop is everything. Older two cycle motors liked 6200 rpm (peak horsepower that didn't destroy the motor) A lower pitch the boat accelerates quicker, air planes climb faster but neither goes its potential for speed. Now electric motors are different from gas. There is a pitch that works best for longevity (flying time) If I wouldn't have seen the second Dat. chart I would have thought that the left rear corner was heavy and the prop had to spin faster to hold up the corner. If you put the old and new props under a microscope you probably can't see a difference. Changing the props definitely brought the RPMs in line don't you think.

Suggest moving bad prop (set of matched blades) to opposite rear motor.
Followed by one of front motors.  Each time capturing .DAT file to see what log shows for motor RPM with bad prop.

As far as visually inspecting prop (blades) under a microscope, likely won't see anything.  Comparing pictures of good props to bad props while props are at rest and under stress (100% throttle with MM strapped down); might show a difference.

Deucalion Posted at 4-27 11:56
Actually, not many people are getting this error now AFTER they connect to DJI Assistant and make sure that the firmware update is successful. I was worried that the trigger was too sensitive as well, but the handful of users who still have prop issues after a successful FW update seem on the same order (number) as those getting errors before the FW update. In other words, maybe they do need to replace their props. Those that do seem to fix the issue. That is not to say that the trigger for the prop warning or the previous uncommandered descent is too sensitive, but since it is now back to a handful, maybe the correct course is to just change the props. If after changing the props, this handful is able to fly as freely as the rest of us, then I would say that is a fix.

It would point to some MM owners having bad props.  But wouldn't really fix the problem, because nobody would know whether their spare props (or ones they were buying) were bad unless they tested them.   

The bad props could be from a bad batch during manufacturing or perhaps how props were stored.  Issue is, unless DJI analyzes bad props and figures out cause, there is potential for another batch of bad props to get into supply chain.

jonny007 Posted at 4-27 11:49
Maybe, why not. Up to 1.0.5, a fly was able to sit on the left rear arm during the flight without causing an error. This is now different.
I think the (new) procedure / function that measures the load of the individual motors and brings an error message, if the imbalance is too great, has trigger points that are too sensitive. This would explain that many people get this message even though they have never had any problems before, neither ESC errors nor uncommanded descents.

...so, is like taking off with left pedal and cyclic to counter-act an off balance machine...?