djiuser_1eaQD2c75tGQ Posted at 5-6 19:14
This is an update problem.  I have a brand new mavic mini.  There is nothing wrong with the props.   I just bought this drone.   

Its impossible that all of a sudden everyones props are damaged.

It is probably about 10%, but I agree, the update probably should have flagged 5% of the props, not 10%. Less than 1% fell from the sky due to bad props, so flagging 10% of the props seems overkill, but maybe not. Most haven't had any issues or errors with the original props since they got the drone. Will be interesting what they say.

Deucalion Posted at 5-6 19:22
It is probably about 10%, but I agree, the update probably should have flagged 5% of the props, not 10%. Less than 1% fell from the sky due to bad props, so flagging 10% of the props seems overkill, but maybe not. Most haven't had any issues or errors with the original props since they got the drone. Will be interesting what they say.

Doubt DJI would go to all trouble of writing, testing, re-writing, and re-testing changes to firmware to identify bad blades (or potentially bad blades); unless DJI knew there was a batch (or batches) of bad (ccw?) blades.  With some of bad blades getting installed on Mavic Mini at factory and / or bad blades sent along as spares.

With falloff in reported Un-commanded descents being result of FW warning pilots to replace bad blades.  In some cases, merely swapping bad blades to front right, may reduce stress on blades enough they don't cause problems.  

It would help, if DJI communicated to their customers what they do know, and why they did make changes to firmware.  

HedgeTrimmer Posted at 5-6 21:20
Doubt DJI would go to all trouble of writing, testing, re-writing, and re-testing changes to firmware to identify bad blades (or potentially bad blades); unless DJI knew there was a batch (or batches) of bad (ccw?) blades.  With some of bad blades getting installed on Mavic Mini at factory and / or bad blades sent along as spares.

With falloff in reported Un-commanded descents being result of FW warning pilots to replace bad blades.  In some cases, merely swapping bad blades to front right, may reduce stress on blades enough they don't cause problems.  

They did not rewrite the FW to identify bad blades, they did it to identify discrepancies in motor speed (which is the name of the error message itself) and several have confirmed this by looking at the .DAT file. We have seen that usually the rear left motor is running faster as the others and that after a blade change this went back to normal. Fewer affected users infortunately bothered swapping back their old prop to see if the problem came back, but one of them has already reported that swapping a reportedly faulty prop rear left to front right led to the error message correctly identifying the issue on the front right after a 3rd flight (on mavicpilots forum, see https://mavicpilots.com/threads/motor-speed-error-mavic-mini.86130/page-7#post-983094). Ideally, anyone who has this issue should: 1. try to swap back and forth old and new props or change position and 2. systematically get the .DAT file and verify motor speeds. Incidentally, several have also reported there may be a connection with non updated batteries and discrepancy between FW versions of the drone and the batteries. But again without data this is speculation.

zeb_ Posted at 5-6 23:39
They did not rewrite the FW to identify bad blades, they did it to identify discrepancies in motor speed (which is the name of the error message itself) and several have confirmed this by looking at the .DAT file. We have seen that usually the rear left motor is running faster as the others and that after a blade change this went back to normal. Fewer affected users infortunately bothered swapping back their old prop to see if the problem came back, but one of them has already reported that swapping a reportedly faulty prop rear left to front right led to the error message correctly identifying the issue on the front right after a 3rd flight (on mavicpilots forum, see https://mavicpilots.com/threads/motor-speed-error-mavic-mini.86130/page-7#post-983094). Ideally, anyone who has this issue should: 1. try to swap back and forth old and new props or change position and 2. systematically get the .DAT file and verify motor speeds. Incidentally, several have also reported there may be a connection with non updated batteries and discrepancy between FW versions of the drone and the batteries. But again without data this is speculation.

I wonder about the savvy of people and the need to try spreading ridiculous theory’s, I think the coincidence would be so enormous that all bad props ended up on the same motor that DT was right inject disinfectant is good for you. Many here also thought updating battery may have been causing problems.

Dr. Alex Posted at 5-6 12:10
I already ordered a propeller holder from AliExpress along with yagi antenna

I’ve used these since December, they’re great.

hallmark007 Posted at 5-7 01:53
I wonder about the savvy of people and the need to try spreading ridiculous theory’s, I think the coincidence would be so enormous that all bad props ended up on the same motor that DT was right inject disinfectant is good for you. Many here also thought updating battery may have been causing problems.

Well, the few people who published .DAT files after the error show the motor speed being higher than the others. This is factual and seems consistent. Now the cause of this: a propeller, a battery firmware or a software bug (not in the detection, but in the management of motor rpms) needs to be verified. If this is due to the props, then a worry is that the tolerance between a good and bad prop are very tight on the mini, and not very well controlled at production level.

zeb_ Posted at 5-7 02:27
Well, the few people who published .DAT files after the error show the motor speed being higher than the others. This is factual and seems consistent. Now the cause of this: a propeller, a battery firmware or a software bug (not in the detection, but in the management of motor rpms) needs to be verified. If this is due to the props, then a worry is that the tolerance between a good and bad prop are very tight on the mini, and not very well controlled at production level.

Minimal tolerance between good and bad prop?

Still original props here since January...rears are a bit scuffed and not as "pretty" as when I received the thing.

No problems whatsoever.

...maybe some batch of motors are more intolerant to props.

...me think it's more than a prop story here...time will tell.

Bottom line, no more uncommanded descents.

HedgeTrimmer Posted at 4-24 13:14
People have been replacing props with new props and the error goes away. Not switching. Replacing.

Which would confirm the Props (matched set of blades) are defective or being deformed.  Whether it be from factory, caused by bad DJI storage cases, or improper storage.  Like being shoved into a backpack without carrying case.

So I replaced props due to this error. Then I got the error again for the left rear. I shut my drone down and flew it the next day with no error without re replacing props. Then flew it again got another error but for the right side this time.  Dude it’s a bug in software!!!

zeb_ Posted at 5-6 23:39
They did not rewrite the FW to identify bad blades, they did it to identify discrepancies in motor speed (which is the name of the error message itself) and several have confirmed this by looking at the .DAT file. We have seen that usually the rear left motor is running faster as the others and that after a blade change this went back to normal. Fewer affected users infortunately bothered swapping back their old prop to see if the problem came back, but one of them has already reported that swapping a reportedly faulty prop rear left to front right led to the error message correctly identifying the issue on the front right after a 3rd flight (on mavicpilots forum, see https://mavicpilots.com/threads/motor-speed-error-mavic-mini.86130/page-7#post-983094). Ideally, anyone who has this issue should: 1. try to swap back and forth old and new props or change position and 2. systematically get the .DAT file and verify motor speeds. Incidentally, several have also reported there may be a connection with non updated batteries and discrepancy between FW versions of the drone and the batteries. But again without data this is speculation.

You might have just gotten here, but this is a months old problem. It goes back to when the drone came out. The root cause is high RPM, and the only way to have high RPM is if the suspect prop is less efficient. The message appears when a prop exceeds a certain RPM, not if there is wide discrepancy between props. The drone can handle prop differences fine, unless a motor is nearing the maximum RPM it can go, and then you will get the warning. In any event, prior to this update, a handful of drones were  descending mid-flight because of bad props and the motor could not turn any faster and the drone went down. The logs of those drones contained a lot of max speed messages. This FW update now gives a warning before that happens.

I have never had either issue. No errors and no warnings. With original props. I even swapped around all of my new props and while I had a couple that had much higher rpms than the others, they were evidently not high enough to trigger a warning. And the vast majority of users have had no errors or warnings with their original props, even after the FW update.

On the other hand, a lot of users are getting this warning, even on brand new drones. And I should note that some of the drones that went down were also new. Some props seem bad, while most seem unaffected, even after many hours and miles of flying. It has been very rare thus far for users to have to replace their props twice. Which further supports the idea that there are a % of bad props out there.

zeb_ Posted at 5-7 02:27
Well, the few people who published .DAT files after the error show the motor speed being higher than the others. This is factual and seems consistent. Now the cause of this: a propeller, a battery firmware or a software bug (not in the detection, but in the management of motor rpms) needs to be verified. If this is due to the props, then a worry is that the tolerance between a good and bad prop are very tight on the mini, and not very well controlled at production level.

I’ve seen people demonstrate flying with sniped ends of the props and there was no loss of altitude, and I have seen people with brand new props get warning, but in just over two weeks I haven’t seen any descents I’ve heard of one but with no log it cannot be verified. Since FW update my craft is much improved and it’s nothing to do with props.

There seems to be enough posts in this thread from users who have fitted new props then got the warning message reappear to suggest there are more factors than just props. It seems very common for one of the rear motors to spin faster than the other (but not generate any warnings).

As an aside, anyone noticed that the DJI website shows 6 pairs of spare props in the flymore combo in the pictures but then lists just 3 in the small print? Didn't really bother me until these messages appeared telling me to chuck props away left, right and center

itchyeyeballs Posted at 5-7 03:50
There seems to be enough posts in this thread from users who have fitted new props then got the warning message reappear to suggest there are more factors than just props. It seems very common for one of the rear motors to spin faster than the other (but not generate any warnings).

As an aside, anyone noticed that the DJI website shows 6 pairs of spare props in the flymore combo in the pictures but then lists just 3 in the small print? Didn't really bother me until these messages appeared telling me to chuck props away left, right and center

I had 3 little baggies each containing 4 props, I don't know about the others but that seems right to me.

ABeardedItalian Posted at 5-7 04:09
I had 3 little baggies each containing 4 props, I don't know about the others but that seems right to me.

Your right! I'm an idiot

I hadn't inspected the packages until now, assumed only 1 pair in each

itchyeyeballs Posted at 5-7 03:50
There seems to be enough posts in this thread from users who have fitted new props then got the warning message reappear to suggest there are more factors than just props. It seems very common for one of the rear motors to spin faster than the other (but not generate any warnings).

As an aside, anyone noticed that the DJI website shows 6 pairs of spare props in the flymore combo in the pictures but then lists just 3 in the small print? Didn't really bother me until these messages appeared telling me to chuck props away left, right and center

I have only seen a couple users replace props twice. Not saying it won't happen, that users have to start re-replacing props, and if it gets to that, we will know it.

zeb_ Posted at 5-6 23:39
They did not rewrite the FW to identify bad blades, they did it to identify discrepancies in motor speed (which is the name of the error message itself) and several have confirmed this by looking at the .DAT file. We have seen that usually the rear left motor is running faster as the others and that after a blade change this went back to normal. Fewer affected users infortunately bothered swapping back their old prop to see if the problem came back, but one of them has already reported that swapping a reportedly faulty prop rear left to front right led to the error message correctly identifying the issue on the front right after a 3rd flight (on mavicpilots forum, see https://mavicpilots.com/threads/motor-speed-error-mavic-mini.86130/page-7#post-983094). Ideally, anyone who has this issue should: 1. try to swap back and forth old and new props or change position and 2. systematically get the .DAT file and verify motor speeds. Incidentally, several have also reported there may be a connection with non updated batteries and discrepancy between FW versions of the drone and the batteries. But again without data this is speculation.

"They did not rewrite the FW to identify bad blades, they did it to identify discrepancies in motor speed (which is the name of the error message itself)"

Ignoring motors running at different speeds due to Mavic Mini trying to hover, RTH, or follow pilots commanded input.   

Why would there be discrepancies in motor speeds?  

Or why would one motor need to turn signifcantly faster than other three motors?

fans1cafe718 Posted at 5-7 02:44
Minimal tolerance between good and bad prop?

Still original props here since January...rears are a bit scuffed and not as "pretty" as when I received the thing.

As you say there could be more to this story.
Two separate problems being addressed by FW.  Or FW addressing un-commanded descent problem, by coincidence, brought to light bad blade problem.

Adding on to idea of minimal tolerance...
A prop is always supposed to be replaced as matched pair of blades.
Assuming for moment there was a bad batch of blades (ccw?), there could be four prop combinations, leading to three different thrust levels.
Good blade & Good blade --- Full thrust prop
Good blade & Bad blade --- Reduced thrust prop
Bad blade & Good blade --- Reduced thrust prop
Bad blade & Bad blade --- Marginal thrust prop

With marginal thrust prop (Bad blade & Bad blade) still providing enough thrust to work when moved to Right Front.

HedgeTrimmer Posted at 5-7 06:19
"They did not rewrite the FW to identify bad blades, they did it to identify discrepancies in motor speed (which is the name of the error message itself)"

Ignoring motors running at different speeds due to Mavic Mini trying to hover, RTH, or follow pilots commanded input.   

Well if you read earlier posts showing motor rpm data from .DAT file analysis you will see exactly that, a LR motor significantly faster than the others. The why is not clear, but changing prop restores normal speed and ends error message display.

zeb_ Posted at 5-7 06:37
Well if you read earlier posts showing motor rpm data from .DAT file analysis you will see exactly that, a LR motor significantly faster than the others. The why is not clear, but changing prop restores normal speed and ends error message display.

"The why is not clear, but changing prop restores normal speed and ends error message display."

As you say, changing prop restores normal speed.  Leading to "the why", being bad prop (aka pair of matched blades).

HedgeTrimmer Posted at 5-7 06:55
"The why is not clear, but changing prop restores normal speed and ends error message display."

As you say, changing prop restores normal speed.  Leading to "the why", being bad prop (aka pair of matched blades).

I have a brand new mini.  I updated firmware and got the motor speed error.  I changed the props, still got the error.  Went back to previous version of firmware, no moto speed error.  Updated firmware to 0500, one flight and the motor speed error comes back.  This has to be an issue with the latest firmware release.

UK01 Posted at 5-7 15:38
I have a brand new mini.  I updated firmware and got the motor speed error.  I changed the props, still got the error.  Went back to previous version of firmware, no moto speed error.  Updated firmware to 0500, one flight and the motor speed error comes back.  This has to be an issue with the latest firmware release.

The new FW add a motor error when speed of a given motor passes a safe limit. Removing the message do not eliminates the root cause of the problem, usually flatten propellers. When the error comes after replacing the propellers it can be caused by an incomplete firmware update using the DJI Fly app. Try to refresh the firmware with the PC using the DJI Assistant with alll batteries you have and the controller.

I would recommend anyone who still doubts whether bad props are responsible for these Motor Error warnings, as well as uncommanded descents, to read this thread on the MavicPilots forum, by a well-known member (SAR104).

120ccpm Posted at 5-7 16:27
I would recommend anyone who still doubts whether bad props are responsible for these Motor Error warnings, as well as uncommanded descents, to read this thread on the MavicPilots forum, by a well-known member (SAR104).

thx for link,

...but my mini flies as solid as it did when new...be it in in wind, scuffed props, new firmwares, new fly apps...so?

...and all original props...in Canada...winds...cold...humidity...etc...

...only prob ever was stuck gimbal....which is easy-peasy to fix...

...did I get a super-duper mini??

UK01 Posted at 5-7 15:38
I have a brand new mini.  I updated firmware and got the motor speed error.  I changed the props, still got the error.  Went back to previous version of firmware, no moto speed error.  Updated firmware to 0500, one flight and the motor speed error comes back.  This has to be an issue with the latest firmware release.

It is possible the 0.500 FW is signaling false Positives.  Code parameters set a little to sensitive.  Case of better to error on side of caution, than have prop fail and drone crash.  

Also possible prop (pair of blades) you put on were also bad.  From what is been said, you can't visually tell known good pair of blades from pair of blades flagged as bad.  Been couple of pictures showing bad blades being slightly flatter, less pitch.

Bad batch (or batches) of blades could have been put on new Mavic Minis, in spares for Mavic Minis, or both.  With most Mavic Minis and spares for Mavic Minis getting perfectly good blades.  Without manufacturing tracking information, drone SN / date produced, batch numbers of assemblies, and batch numbers of sub-assemblies, and parts there is no way to know.

Unless DJI starts communicating with their customers, we can only speculate.

I think all they did was lower the severity of the message from Critical (which might prompt an uncommanded descent)  to Warning (which just posts a popup in the interface). As to what causes the message, only a DJI dev that has access to the code might tell you. Could be bad firmware, could be bad props, could be bad engines, could be batteries or combinations of each.

DJI has now released a statement: https://forum.dji.com/forum.php?mod=viewthread&tid=214705 blaming the issue on bent or damaged props, and reminds proper storage as shown on the case image.
Unfortunately that does not explain why some people have experienced the error with brand new Minis, unless there have been a production of defective props. Another strange thing is that they say "If the propellers are slightly misshapen, can straighten them out and retest to ensure the issue  has ben resolved. " What is "misshapen" and "straighten out"? What if there is no visible difference, as reported by some users? Is it reasonable to ask people to shape their props if a tiny change can lead to the problem?

Another one in the motor speed error.. I bought my mini at the end of April.. Updated the firmware out of the box.. Flew three times around the garden for about five minutes each .. Fourth flight yesterday I get the motor speed error..

I mean I have less then 30 minutes total flight time, have not stored it in the case, didn't crash.. Now I have to buy new props..?!   Pretty poor.

Bob_D Posted at 5-8 00:14
Another one in the motor speed error.. I bought my mini at the end of April.. Updated the firmware out of the box.. Flew three times around the garden for about five minutes each .. Fourth flight yesterday I get the motor speed error..

I mean I have less then 30 minutes total flight time, have not stored it in the case, didn't crash.. Now I have to buy new props..?!   Pretty poor.

Edit > Are the props supposed to be all identical.. Mine are original, as factory fitted but I see that they are not all 4 the same.. I have two slight variations, each diagonal is same.. See pic. slight difference in paint stripes.

Bob_D Posted at 5-8 00:40
Edit > Are the props supposed to be all identical.. Mine are original, as factory fitted but I see that they are not all 4 the same.. I have two slight variations, each diagonal is same.. See pic. slight difference in paint stripes.
[view_image]

You have CW and CCW props, they are dstinguishable by those marks.

Sorry for the multiple posts .. Maybe a moderator can combine them...

But I've just refresh the firmware with DJI Assistant.. Problem gone.. Didn't change any props..

I flew for 20 mins in light wind conditions and sport mode, real up, down erratic flying and it was solid.. No error.

Conclusion..?

Bob_D Posted at 5-8 01:11
Sorry for the multiple posts .. Maybe a moderator can combine them...

But I've just refresh the firmware with DJI Assistant.. Problem gone.. Didn't change any props..

As I stated before: we do not know the algorithm behind the error message triggering. Could be an averaging of several motor speed events, over several flights, explaining why one user who swapped props had only the error coming back after a 3rd flight. Now refreshing the FW may lead to deleting flight history and thus you think you have fixed the issue when you only cleared the error message. The only way would be to download the .DAT file after each flight and look at the rpm data, since we know from some users the speed error is linked to a motor having a higher speed than the others.

120ccpm Posted at 5-7 16:27
I would recommend anyone who still doubts whether bad props are responsible for these Motor Error warnings, as well as uncommanded descents, to read this thread on the MavicPilots forum, by a well-known member (SAR104).

I fail to see how you can definitely say this is only a prop fault, or it looks like you’re pushing this idea, I think with tests shown here this was not proved and I think if you look at what BW is saying there is some skepticism there.
SAR set out to prove that props and only props were the cause, and in doing so he had to purposely damage props to prove that damaged props were the cause, now there is not much logic in that. No matter what dji craft you fly damaged props will have a negative effect, so the test with the pre damaged props proved one thing, that damaged props are not good to be flying around with.
Also above test was also proven not to be like others seen and props were trashed to prove point.

A simple observation here over the last 3 weeks here has shown no uncontrolled descents including old craft and new craft. What we have seen is warnings to people to change on the whole one prop rear left, but many get this warning after days of loading new FW, and not a single one pre warning has noticed any drop outs no uncontrolled descents, “none” . If we were to believe yourself and SAR we would surely see some uncontrolled descents drop outs, pre getting the warning, but it hasn’t happened yet.
In order to prove it’s bad props we are now being asked to believe that descents are not happening because people are changing props, but we have seen so many only change “so called” bad props after many flights but not one saying they had drop outs uncontrolled descents etc, yet according to both you and SAR their props are bad so aircraft should be descending uncontrollably, but their not.Dji have issued statement regarding how you store your craft in relation to props, so telling users that using bad props is both visible and bad, the warnings are on all motors, but seems only one motor is doing any warning and this includes many brand new props, so it's likely that the left rear motor is set very sensitive.

I also think that yourself and to some degree SAR have ignored that what many have said, that they have noticed their craft flying more stable and better since last FW update.


I believe the problem was much smaller than it looked, because of large debates etc it highlighted a problem that users found was everything from temperature to motors to barometres to props, I don’t think any of these were unequivocally proved or disapproved.
I think the only problem we have with props are that they are light and need to be checked, I don’t think props need to be X-rayed and I don’t believe props have invisible damage or there is bad batches out there.
I'm glad that there has been a big improvement in uncontrolled descents. It just shouldn't happen.

zeb_ Posted at 5-8 01:46
As I stated before: we do not know the algorithm behind the error message triggering. Could be an averaging of several motor speed events, over several flights, explaining why one user who swapped props had only the error coming back after a 3rd flight. Now refreshing the FW may lead to deleting flight history and thus you think you have fixed the issue when you only cleared the error message. The only way would be to download the .DAT file after each flight and look at the rpm data, since we know from some users the speed error is linked to a motor having a higher speed than the others.

People were not refreshing the FW to fix the prop error, they were refreshing the firmware to fix the firmware error that appeared when they connected the drone to DJI Assistant. Also, many people got the error right after the FW update.

Bob_D Posted at 5-8 00:40
Edit > Are the props supposed to be all identical.. Mine are original, as factory fitted but I see that they are not all 4 the same.. I have two slight variations, each diagonal is same.. See pic. slight difference in paint stripes.
[view_image]

They're not meant to be the same.  Have a look on the arm of prop shafts. If there is a small raised line, then you should have a prop with two stripes.  If there isn't a mark, then a prop with one stripe.  

Bob_D Posted at 5-8 00:40
Edit > Are the props supposed to be all identical.. Mine are original, as factory fitted but I see that they are not all 4 the same.. I have two slight variations, each diagonal is same.. See pic. slight difference in paint stripes.
[view_image]

They're not meant to be the same.  Have a look on the arm of prop shafts. If there is a small raised line, then you should have a prop with two stripes.  If there isn't a mark, then a prop with one stripe.  

Deucalion Posted at 5-8 05:39
People were not refreshing the FW to fix the prop error, they were refreshing the firmware to fix the firmware error that appeared when they connected the drone to DJI Assistant. Also, many people got the error right after the FW update.

Indeed but the side effect may be that they reset the warning too. Only DJI can help explain how this error triggers I mean mathematically.

all I did was refresh the update on DJI ASSISTANT 2, it fix my motor error. hope it will help others.

Joker0918 Posted at 5-8 06:27
all I did was refresh the update on DJI ASSISTANT 2, it fix my motor error. hope it will help others.

By doing that you rewrite the FW. If that also resets some data used for triggering the error then it might reappear later.

zeb_ Posted at 5-8 06:34
By doing that you rewrite the FW. If that also resets some data used for triggering the error then it might reappear later.

after reading your reply, I went outside and did some flight test, good 20 minutes, or so.no issues yet. shoot hopefully it doesn't come bach.haha

fans1cafe718 Posted at 5-7 16:49
thx for link,

...but my mini flies as solid as it did when new...be it in in wind, scuffed props, new firmwares, new fly apps...so?

Mine too, and probably that is true for the vast majority of MM owners out there.

But it's undeniable that MM props are a bit of a hit-or-miss, and these tests (SAR104 on MavicPilots, ABeardedItalian & others here) prove beyond doubt that there are indeed bad props around, and they cause Motor Error warnings and uncommanded descents. They also show quite clearly that these "bad props" are not obviously deformed or damaged: the visible differences are minimal, but that's enough to cause problems. The increase in RPMs is real, tangible and measurable.

120ccpm Posted at 5-8 10:51
Mine too, and probably that is true for the vast majority of MM owners out there.

But it's undeniable that MM props are a bit of a hit-or-miss, and these tests (SAR104 on MavicPilots, ABeardedItalian & others here) prove beyond doubt that there are indeed bad props around, and they cause Motor Error warnings and uncommanded descents. They also show quite clearly that these "bad props" are not obviously deformed or damaged: the visible differences are minimal, but that's enough to cause problems. The increase in RPMs is real, tangible and measurable.

You are completely delusional, it’s so very obviously clear that abeardeditallian damaged his props in order to get the test to go the way he wanted and also SAR did exactly the same , you’re in complete denial regarding bad props, if user damaged his props then he has damaged props that’s a given, but you’re saying that perfectly brand new props have some unseen damage of which there is absolutely no proof whatsoever, and all your doing is trying to flog a dead horse without a scintilla of evidence none nada, just your delusions in order to prove that props have unseen damage. It’s a complete crock and you know it.