Mavic Mini class action info speed error

[Niterunnr]

Thanks again for all your relevant insights Zbip57
It would be nice to see this much attention to detail from DJI. My storage solution (post #28) that only allows the front legs to touch the case and floats the rest should be possible to achieve with a large number of cases by cutting the foam. Another option is storing the craft on it’s side or back end, once again preventing the craft from resting on the blades.

 

[Brojon]

I can't take this post serious due to the hyperbole such "prevent a tragedy"?
This is a 249g drone that couldn't knock out a chipmunk if it fell from 400 feet.
As mentioned it's teh operators responsibility to inspect the drone before flight.
It is NOT DJI's responsibility to provide an idiot-proof storage device to guarantee the blades stay true.
Those type prop holders have been aftermarket since forever. Note aftermarket.
All the gizmos and farkles are sold to folks that perceive a need but aren't critical components.

 

[Deleted member 103366]

If anyone has what might be the original MM flymore case with the stepped floor, try storing the mini in that case with the rear blades as shown in the attached.
I think you will find they are hanging in mid air with no weight on them and they do NOT need to be bent to get them into that position.
I put VERY soft margarine in a cling film 'bag' on the floor of the case and squashed the margarine into a thin layer that 'covered' the case floor, the blades left not the slightest mark in the margarine. I have stored my MM like that for 7 months and the props are unwarped, (though somewhat battered by the looks of it )

 

[Zbip57]

I can't take this post serious due to the hyperbole such "prevent a tragedy"?
This is a 249g drone that couldn't knock out a chipmunk if it fell from 400 feet.
As mentioned it's the operator's responsibility to inspect the drone before flight.
It is NOT DJI's responsibility to provide an idiot-proof storage device to guarantee the blades stay true.
Those type prop holders have been aftermarket since forever. Note aftermarket.
All the gizmos and farkles are sold to folks that perceive a need but aren't critical components.

I think you're still missing the point.

Even responsible operators might be totally unaware that their propeller blades are deformed. As I've shown in the photos above, the deformation may not be at all obvious. Unless you know what to look for, the props may appear perfectly fine using just a visual inspection. The only sure fire method for actually measuring the prop's performance is with a hover test, then graphing and comparing the motor speed plots.

Have you ever done such a test, let alone during every pre-flight?

Whether or not there is any risk of an actual "tragedy" depends entirely on the circumstances of where you fly. An uncommanded descent and terminal loss of your Mini into a lake may well qualify as a full-blown tragedy to some people.

"Those type prop holders have been aftermarket since forever. Note aftermarket."

The Mavic Mini (both the Standard and Fly More Combo versions) were sold and shipped with their arms folded and blades crossed laterally, with the blades secured into that position by paper straps. That alone caused sufficient blade deformation that many people reported getting Motor Speed Error warnings on the very first flight with their Minis. That is very much DJI's responsibility and no fault of the operator.






Note the relative height of the tips of the left-rear blades versus right-rear. The left blades are forced to bend under the right-rear blades. This is not aftermarket. This is direct from DJI.


Many more people have reported, as instructed by the error message, that they replaced the defective propeller blades on the motors identified by the beeping ESC, only to suffer the exact same warning message again soon thereafter. That is very likely because they've stored their Mini, as instructed by DJI, with the arms folded and blades "properly" crossed as shown in the diagram in the bottom of the Fly More Case.

Again, this is not aftermarket. This is directly according to DJI's instructions.


"Those type prop holders have been aftermarket since forever. Note aftermarket."

Yes, the stretchy orange latex prop holders (Type#2 in the original poster's image) are just one example of the many available aftermarket products.

However, the hard-shell Type#1 prop holder is an accessory that was sold directly by DJI and is still shown on their webpage for the Mavic Mini.


"It is NOT DJI's responsibility to provide an idiot-proof storage device to guarantee the blades stay true."

Huh?

Sure, if you buy non-OEM aftermarket products, you're on your own. It's buyer beware. But if you purchases a product directly from DJI, you should have some expectation of confidence that you've been supplied with a quality product.

DJI have since quietly made changes. They made a slight alteration to the Fly More Case, in my opinion making it even worse. It still has a label in the bottom recommending the props should be folded laterally.

But DJI have never acknowledged that an issue even exists. They just say to replace the prop blades, but don't explain why the blades are being deformed.

If you read through this entire thread and choose to ignore what you see here, then continue storing your Mini with the blades crossed, then yes, that clearly becomes a case of operator error beyond the responsibility of DJI.

But, in the complete absence of a remedy or mitigation from DJI, any newbie receiving an original Mavic Mini for Xmas risks losing their drone through no fault of their own if they continue to follow the current instructions of DJI.

 

[maelstrom]

But, in the complete absence of a remedy or mitigation from DJI, any newbie receiving an original Mavic Mini for Xmas risks losing their drone through no fault of their own if they continue to follow the current instructions of DJI.

Whilst I’m in no way saying that deformed blades may not cause issues, most, if not all, Minis have potentially been stored before sale for many months with their blades crossed. You’d think that everyone who bought one would be experiencing problems and that doesn’t seem to be the case. Why is that?

 

[Zbip57]

Minis have potentially been stored before sale for many months with their blades crossed. You’d think that everyone who bought one would be experiencing problems and that doesn’t seem to be the case. Why is that?

Who knows? Maybe everybody actually is experiencing problems but they just haven't realized it yet. The forums are full of people complaining about the mysterious Motor Speed Error and/or Propeller Speed warning. Long before that, and still today, it was Max Power Reached warnings. There are posts everywhere from people asking what those warnings are supposed to mean, and what's up with this beeping ESC thing anyway?

Many people simply disregard these warnings and just keep flying, and sometimes the warnings never reappear. That just means the props are only marginally deformed and only triggered the warning under some extreme flying condition that hasn't (yet) been repeated.

But what's really scary is that there are people replying to those questions with bad advice to ignore the warnings because the firmware is obviously faulty, it's a firmware bug, because they can see nothing visibly wrong with their propeller blades. Some people even recommend downgrading to a previous firmware version because this "bug" didn't appear in previous versions.

Really, if you're at all concerned, do the hover test and plot the motor speeds. It's the only way to know for sure.

Check out this thread on the DJI Forum. It has been viewed 39k times, with over 300 replies, and still people just don't get it. The topic thread is pinned to the top of the Mavic Mini forum and contains this dubious advice direct from DJI Support: forum.dji.com/forum.php?mod=viewthread&tid=214705

"Note: To help prevent this from occurring, pilots should follow the proper storage procedure for the aircraft. For reference, please refer to the image below. Please notice the placement of the rear arm propellers. Make sure the propellers are folded horizontally so that they are not pressed down upon during transportation. Pilots are also recommended to check the aircraft propellers before every flight."

 

[Zbip57]

DJI have since quietly made changes. They made a slight alteration to the Fly More Case, in my opinion making it even worse.

I contacted DJI Support back in June explaining how and why storing the Mini with blades crossed causes the props to deform. They assured me that my concerns would be forwarded up the line for further action. But I never heard anything back.

This November I discovered, from another post in the DJI forum, that DJI actually has modified the Fly More Case with two differences.

First, that label in the bottom of the case. Sheesh. This original label said to store the blades crossed with the left-rear blades folded under the right-rear blades. But it's obviously impossible to fit the blades together exactly as shown in this diagram. Note the left-rear blades with A under B.



Here you can see that it is not possible to squeeze the leading edge of A under the trailing edge of B.



Well, that's one thing that DJI "fixed" in the 2nd generation of their Fly More Case. Their new label now looks like this. Now A goes over B. But note that they have also reversed the order so now it's the right-rear blades that are being bent to fit under the left-rear, whereas previously it was the other way around.

If you now religiously store your blades as shown in DJI's new diagram, I predict the Motor Speed Error and beeping ESC will always trigger first on the right-rear motor, whereas previously it was almost always first the left-rear.

Either way, DJI still recommends crossing the blades for storage.



I'll get to the 2nd difference in the new Fly More Case in just a moment...

 

[Zbip57]

DJI have since quietly made changes. They made a slight alteration to the Fly More Case, in my opinion making it even worse.

Here's what's wrong with the original Fly More Case, and even moreso with the redesigned v.2 Fly More Case.

When the Mini is set with arms open onto a flat surface, you can see that it rests on its four feet with only a tiny bit of ground clearance under its belly.


When the arms are folded for storage, all four feet are now positioned at the tail of the Mini. The nose of the Mini will rest right onto that point of low clearance, which is exactly where the rear propeller blades will end up if folded together to nest laterally across the body.


My original Fly More case has a raised block (orange) in the bottom of the case. The belly of the Mini is raised up and supported by that block. The folded back feet (red boxes) hang into the trough at the rear. The propeller blades, when folded under and across the body of the Mini, hang freely into the trough at the front (red oval).

Obviously you need to be careful never to incorrectly position the blades allowing them to flop back on top of the raised block (orange), as then the weight of the Mini will be resting on the blades. The whole intent of that trough at the front (red oval) is to provide a space into which the rear blades can droop and hang freely.

BUT, as shown in previous photos, merely forcing the blades to "properly" cross like this is already enough to cause the blades to bend.


So here's the redesigned v.2 Fly More Case. In the redesigned case the large central block is gone!. Instead there is a small raised block (orange) between the Mini's feet (red boxes) supporting only the tail end of the Mini. That does nothing to keep the weight of the Mini off the prop blades. If the rear blades are folded under and across the body of the Mini, as recommended in DJI's diagram, the full weight of the Mini will now rest directly on the propeller blades (red oval).


There is no support under the belly of the Mini. The floor of the new case is flat. The Mini is resting directly onto the folded propeller blades!

What is the point of that new small raised block (orange) under just the tail of the Mini? The only possible purpose of that is to support the Mini's feet. When the legs are folded back, the front feet are significantly taller than the rear feet. Without that small support block propping up the tail of the Mini, any pressure on the case might otherwise force those taller front feet to puncture the bottom of the case.

But with no longer any support under the belly of the Mini, obviously its weight will be resting directly onto the tips of the propeller blades! How in the world is that supposed to be an improvement?


Neither the original Fly More case, nor the redesigned new case, do anything to address the issue of how the blades must bend if forced to fold over/under each other when nested laterally across the body. But having the full weight of the Mini resting directly onto the crossed rear blades in the redesigned case, as is still recommended on DJI's label in the new case, is surely a very bad idea!

 

[maelstrom]

Who knows? Maybe everybody actually is experiencing problems but they just haven't realized it yet. The forums are full of people complaining about the mysterious Motor Speed Error and/or Propeller Speed warning. Long before that, and still today, it was Max Power Reached warnings. There are posts everywhere from people asking what those warnings are supposed to mean, and what's up with this beeping ESC thing anyway?

Or, alternatively, maybe not that many people are actually experiencing these problems. The Internet is famous for a relatively small number of vociferous people making an issue look much more extensive than it really is. I’ve looked around various forums and I’d be surprised if there were as many as even a couple of hundred individuals (not total posts or threads) complaining about this issue online. Most threads of complaints seem to also contain people saying that they haven’t experienced this issue - I haven’t. That’s not to say that people are not genuinely having problems, just that those who are possibly only represent a small fraction of the many thousands of people worldwide who own the Mini. We just have no way of knowing for certain.

 

[DanMan32]

I do agree the new case model seems to be worse than the original. Perhaps the new bump was supposed to be at the front of the AC near the gimbal rather than the back.

I fold my blades acrosd but very gently so that there's minimal tension.

 

[Zbip57]

Or, alternatively, maybe not that many people are actually experiencing these problems. [...] We just have no way of knowing for certain.

I can only speak of my own experience with this issue. I'm a bit of a geek, so I downloaded and studied all the available manuals and read all the forums even before deciding to buy a Mini Fly More Combo for myself in Nov 2019. I've flown my Mini for over a year now. I always took care to store the Mini "properly" with blades crossed and nested carefully into the trough in the bottom of the Fly More Case, and I have never experienced any difficulty flying it.

Over the last year I followed with interest the many forum threads and YouTube videos where people kept reporting mysterious "uncommanded descents". Sometimes they'd see a Max Power Reached warning message. Or, in normal forward flight their Mini would suddenly sag to the ground. No amount of additional throttle would stop the Mini from falling until it bounced off the ground, or plunked into a lake.

In the time I've owned my Mini there were at least four firmware upgrades and multiple Fly App upgrades. Each time people reported the upgrade seemed to have cured their uncommanded descent issues, er, um, nope, $%#, forget that, it's still happening. Why?

Finally, in April 2020, DJI released firmware v01.00.0500 introducing a new Motor Speed Error warning message, with explicit instructions to replace the propeller blades on the motor identified by the beeping ESC.

The forums erupted with people complaining about this annoying new error message. I see nothing wrong with my propeller blades! Why does this stupid message keep popping up telling me to replace the blades? Or worse: I replaced the blades but keep getting the same stupid error message again every time I fly!

A lot of bad advice followed on the forums. It's a corrupted firmware installation. Just reinstall the firmware, that'll fix it. Don't use the app to do the upgrade, use the DJI Assistant instead and that'll fix it. Just ignore the error message, my Mini flies fine even with the message displayed. The error message only appeared after I updated to this latest firmware version. This firmware is obviously defective. You can make it go away by downgrading to the previous version, then wait until DJI releases a proper fix. [DJI has not released any further firmware upgrades since then.]

Eventually some very clever people on this forum determined that it actually was prop deformation that was causing the motor overspeed situations which, if ignored, will eventually result in the dreaded uncommanded descent. The theory was that people just weren't being careful enough when storing their Minis in the Fly More Case, leaving the weight of the Mini resting onto the lower blades. As long as you store the blades nested "properly" you should never have this problem.

However, even people with Standard Minis (i.e. non-flymore) reported the same error messages. Even people with brand new Minis straight out of the box were receiving Motor Speed Errors on their very first flight!

I had sometimes seen the Max Power warnings but typically ignored them because my Mini always continued to fly fine. But on my very first flight with the latest v01.00.0500 firmware I too received the Motor Speed Error warning message, even though it still flew with no problem. On landing the beeping ESC identified the left-rear motor as needing blade replacement.

I posted this short 7-sec clip showing the left-rear beeping ESC back at the start of June. It's been viewed 1,633 times since then, so obviously the issue is still of interest to plenty of people. I received only two comments on that video, "I have the same error", and just last month, "Same error.. How to fix this?". Does that really mean the problem only affected 2 people (3 including me) out of the 1,633 viewers? I suspect the problem is actually far more widespread than that.

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My Mini had always flown perfectly. There was nothing visibly wrong with any of the blades. Not a single scratch, nick, or blemish. I never had any problem folding the props for "proper" storage in the Fly More Case. It made no difference whether the blades were folded right over left, or left over right. They just slid together effortlessly. But I had spare unused prop blades in the Fly More Combo package, so why not just replace those left-rear blades?

That's when I noticed an obvious difference!

The tips of the fresh new blades on the left-rear clearly stand higher than the original flattened blades of the right-rear motor. There's no way the brand new left blades will now fit under the right blades without bending them.

Check how the left blades don't even touch the body of the Mini, whereas the trailing edge of the right blades press against the body of the Mini. Pressing down on the tip, while pressing up on the trailing edge, causes the blade to twist and flatten the pitch angle. That is what eventually generates the Motor Speed Error when the motors can no longer spin fast enough to generate the required lift with flattened prop blades.


Maelstrom (and everybody else), do me a favour and check your rear props. Do they fold easily to nest together? With the front arms folded back like this, where do the tips of your rear props touch the front arms?



If your blade tips are drooped any lower than that, do the Hover Test and plot your Motor Speeds using CsvView. In a stable hands-free hover, all four motors should be turning at a near equal speed of around 9600 rpm.

Let it hover for about 5 minutes to stabilize properly. This test was too short, at just under a minute. Note that it takes the first 30 seconds for the motor speeds to stabilize.

You are correct that we have no way of knowing for certain how many people are affected by this problem. But there is a way of knowing for certain whether YOU are affected.

Your Mini may still be flying fine, and your props may look fine using just a visible inspection, but the Hover Test will demonstrate for certain whether your prop blades are performing up to snuff.

 

[Zbip57]

Let it hover for about 5 minutes to stabilize properly. This test was too short, at just under a minute. Note that it takes the first 30 seconds for the motor speeds to stabilize.

Oh ya, here's just one more example of how DJI has utterly failed to respond effectively to this issue. They "fixed" [Not] the label in the bottom of the Fly More Case, and they improved [Not!] the design of the case. And, in addition to the previous Motor Speed Error warning message, there is now also a Propeller(s) Rotating Too Fast warning message.

And that message further contains this truly bizarre instruction:
The Motor Speed Error message previously said to, "replace the propeller on the beeping ESC".

Now the Propeller Rotating Too Fast message instead merely says to,

Check the propellers. Except, unless there are obvious pieces missing, it's near impossible to detect anything wrong with the blades using a visual inspection.

If warped..., huh? Is it even possible to see whether they're warped or not.

If warped, restart the aircraft and hover in an open area for 5 min or longer to try and straighten the propeller(s).

It's rather coincidental (isn't it?) that we've been recommending a 5-min hover test to record and plot motor speeds in order to determine whether the blades actually need replacing, and now DJI seems to think that holding a 5-min hover will somehow straighten the propeller blades!?!

They've entirely missed the point, yet again! What are they even thinking?

How is hovering supposed to straighten warped blades? Is DJI implying centrifugal loads imposed on the lightweight blade during a gentle 9600 rpm hover are enough to straighten the blades? Then why wouldn't regular flight and horsing the Mini around the sky in full Sport mode at 16,000 rpm peak motor speeds not accomplish this even faster? Their solution makes no sense whatsoever.

I really don't think a Class Action lawsuit is in the cards here. I don't even expect DJI to send everyone a free set of replacement prop blades. But surely they could come up with a credible and reliable explanation of why blade deformation occurs and how to prevent it, starting with proper storage procedures, and just send those instructions to all registered users of the Mini.

 

[maelstrom]

Does that really mean the problem only affected 2 people (3 including me) out of the 1,633 viewers?

Probably not, but views don’t equal problems. I generally view videos and posts about issues I don’t have just so that I stand a better chance of recognising them and the associated solution if they occur for me in the future.

 

[Zbip57]

I generally view videos and posts about issues I don’t have just so that I stand a better chance of recognising them and the associated solution if they occur for me in the future.

Absolutely! I admire people who have the guts to post videos of their crashes so we can all learn from them to avoid making the same mistakes.

These forums (especially this Mavicpilots one) are very educational. There are so many knowledgeable and helpful people here. Far too often I find my previous understanding of some issue is completely backwards and upside-down once it's been better explained by smarter people in these discussion forums.

I'm hoping the stuff I posted in this thread ends up relevant, possibly even useful, for some people. But if anyone has a better explanation for what's causing blade distortion, and can convincingly demonstrate that I'm wrong (yet again), I'll happily eat crow and admit I'm an idiot.

 

[Brojon]

How about you show us how this has been a issue affecting your drone's flying.
This has been 3 pages of a dissertation and defense thereof with no grounding in anything relevant.

 

[Zbip57]

How about you show us how this has been a issue affecting your drone's flying.
This has been 3 pages of a dissertation and defence thereof with no grounding in anything relevant.

I'm very happy to hear that you hung in there for all three pages. But can you be a bit more specific as to which part(s) you find irrelevant?

A quick search of the MavicPilots forum turns up 10 pages of individual topic headings discussing "Motor Speed Error".
mavicpilots.com/search/525801/?page=10&q=Motor+Speed+Error&o=relevance

Another 10 pages of topic headings can be found searching for "Propeller Speed".
mavicpilots.com/search/525811/?q=propeller+speed&o=relevance

Yet another 10 pages of topics are found for "Uncommanded Descent".
mavicpilots.com/search/525815/?q=uncommanded+descent&o=relevance

Or how about "beeping ESC"?
mavicpilots.com/search/525830/?q=beeping+esc&o=relevance

I encourage you to read, if not all, at least some of those topic threads. Evidently there is still a lot of concern, and plenty of misinformation, surrounding these issues.

Are you claiming propeller deformation is not relevant to any of those discussions? Or do you think it's just my dissertation that is irrelevant. Or is it only irrelevant unless I can demonstrate a grounding in how it has personally affected my own drone?

I think most people now accept that it's not a firmware bug but actually is propeller deformation that causes the appearance of these error messages, as evidenced by DJI's instructions to replace the defective propeller blades. There is also plenty of evidence that failure to take effective corrective action is what ultimately leads to Uncommanded Descents.

But, there is still much confusion as to what is causing this propeller blade deformation, or how to avoid it. DJI continues to insist, as per the label in the bottom of the Fly Case, that the Mini should be "properly" stored with the blades crossed. The point of my dissertation is to demonstrate that DJI is wrong and merely crossing the blades will cause them to bend.

If you have any specific questions, I'm more than happy to answer them. Or if you want me to rehash my own personal experience, I'm happy to do that too. Just ask away.

If you disagree with anything I've said and can prove that I'm mistaken, please give us a convincing demonstration or a repeatable experiment so that others can conclusively come up with the same results.

 

[Brojon]

I'm very happy to hear that you hung in there for all three pages. But can you be a bit more specific as to which part(s) you find irrelevant?

A quick search of the MavicPilots forum turns up 10 pages of individual topic headings discussing "Motor Speed Error".
mavicpilots.com/search/525801/?page=10&q=Motor+Speed+Error&o=relevance

Another 10 pages of topic headings can be found searching for "Propeller Speed".
mavicpilots.com/search/525811/?q=propeller+speed&o=relevance

Yet another 10 pages of topics are found for "Uncommanded Descent".
mavicpilots.com/search/525815/?q=uncommanded+descent&o=relevance

Or how about "beeping ESC"?
mavicpilots.com/search/525830/?q=beeping+esc&o=relevance

I encourage you to read, if not all, at least some of those topic threads. Evidently there is still a lot of concern, and plenty of misinformation, surrounding these issues.

Are you claiming propeller deformation is not relevant to any of those discussions? Or do you think it's just my dissertation that is irrelevant. Or is it only irrelevant unless I can demonstrate a grounding in how it has personally affected my own drone?

I think most people now accept that it's not a firmware bug but actually is propeller deformation that causes the appearance of these error messages, as evidenced by DJI's instructions to replace the defective propeller blades. There is also plenty of evidence that failure to take effective corrective action is what ultimately leads to Uncommanded Descents.

But, there is still much confusion as to what is causing this propeller blade deformation, or how to avoid it. DJI continues to insist, as per the label in the bottom of the Fly Case, that the Mini should be "properly" stored with the blades crossed. The point of my dissertation is to demonstrate that DJI is wrong and merely crossing the blades will cause them to bend.

If you have any specific questions, I'm more than happy to answer them. Or if you want me to rehash my own personal experience, I'm happy to do that too. Just ask away.

If you disagree with anything I've said and can prove that I'm mistaken, please give us a convincing demonstration or a repeatable experiment so that others can conclusively come up with the same results.

Good golly you're persistent.
No - you are speculating - plain and simple.
I want to know YOUR demonstrable evidence where you personally have had issues you can prove came about from this heinous situation and lack of concern on the par t of DJI. They put these killer drones on the market with no thought as to safety. Good Lord! The lives lost! Careers ruined! Civilization in shambles!
You are making this scenario up from whole cloth and nothing you speculate on has anything to do with you personally. I think the ambulance chaser tone of your original post is sufficient I don't care to carry this lame conversation on any further.

 

[DoomMeister]

Civility needs to prevail here gentlemen. No need to get snarky with your responses.

 

[Zbip57]

I want to know YOUR demonstrable evidence where you personally have had issues you can prove came about from this heinous situation and lack of concern on the part of DJI. [...] I think the ambulance chaser tone of your original post is sufficient...

Fair enough. Just three things;

One, I do hope you're not confusing me with the original poster of this thread. My initial post in this thread can be found starting at the top of page 2, in which I made it quite clear that I'm not seeking any compensation from, or penalty against, DJI. I am not an ambulance chaser! My intentions were stated in that post (see post#21), where I wrote,

"I don't need DJI to compensate me with a new set of blades or a new prop holder. I don't need money either. But I worry that without an acknowledgement or proper guidance from DJI, people will continue to be unaware of this issue."

Two, I never said, nor implied, that DJI is unconcerned about this issue. They have made numerous changes over the last year to improve the Mavic Mini, changes which prove that they are aware of the propeller deformation issue. They changed the warning messages from the original vague Max Power warnings, to more definite Motor Speed Error or Propeller Speed warnings, with explicit instructions to check or replace the affected propeller blades. They even modified the Fly More Combo carry case.

The intent of my posts in this thread was to demonstrate that, despite the changes already made by DJI, people still continue to experience the same problems because they still store their Mini with the propeller blades crossed. DJI has not done enough to inform people of this danger. The label in the Fly More Case still says to fold and cross the blades.

Three, my own personal experience with this issue has luckily never resulted in any heinous situation due to the fact that I researched the cause of propeller blade deformation, took steps to prevent my props from ever being bent again, and continued to monitor the current health of my props.

I had previously always "properly" stored my Mini, as recommended by DJI, with the props carefully folded and crossed into the Fly More Case. I had never experienced any issues flying it, other than the occasional Max Power Reached warning, which I always treated the same as the Strong Wind Speed warning. Lower altitude, fly carefully, return home, but I never experienced any problems whatsoever in flight.

Like so many other people, on my very first flight after upgrading to firmware v01.00.0500 I received a Motor Speed Error message, with instructions to replace the propeller blades on the left-rear motor identified by the beeping ESC. I could see nothing visibly wrong with any of the propeller blades. But since I had several spare sets included in the Fly More Combo, I went ahead and replaced the left-rear blades.

I was curious to know why I got this error message. Researching the Mavicpilot forums revealed that it's possible to analyze the flight logs recorded by the Fly app, and one can plot the motor speeds as evidence of their performance. I wish I had done a Hover Test before replacing the left-rear blades, but I didn't even know about CsvView before then.

I do however have a plot of the motor speeds from the flight that triggered my Motor Speed Error warning message. The lines jump around because I was flying the Mini back and forth. This was actually two separate flights with a short landing in between. The flat-line sections are where the telemetry stopped recording when I switched the transmitter off to test the Mini's Failsafe functions. The only important thing to note in this plot is that the left-rear motor (blue line) was running consistently faster than the other motors, and at one point it reached a peak speed of nearly 16,000 rpm! The flattened pitch profile of the left-rear blades caused that motor to spin faster to achieve the same required lift.


With new left-rear blades installed, note the significant improvement in the blue line. Now it's the right-rear motor (yellow line) that is spinning consistently fastest.


Next I replaced the right-rear (yellow) prop blades. Note how the blue, red, and yellow lines are now all fairly even, while it is the left-front (green) running consistently the fastest.


It wasn't a critically big difference, just a noticeable and obviously consistent difference in motor speed. The left-front (green) props probably didn't need to be replaced, but for the sake of scientific experiment I also swapped in a set of new left-front prop blades.

Here is the result of a hover test with new props, all except the right-front (red) which is still the original set.


In a steady hands-free hover, with fresh props installed, the motors should all be turning at near equal speed around 9600 rpm.

The point is, even if you cannot visibly detect anything wrong with the propeller blades identified by the Motor Speed Error (ESC) warning, this hover test will conclusively demonstrate whether there is an issue or not.

The graphs document an obvious difference between the motor speeds running on old vs new propeller blades. How much of a difference you are willing to tolerate is up to you. But if any of your motors are running at an elevated speed sufficient to trigger the Motor Speed Error warning, then it's certainly something you should pay attention to.

These graphs are, "demonstrable evidence where you personally have had issues you can prove came about from this heinous situation".

In my case the props were not yet sufficiently deformed to cause any flight instability, but it was enough to trigger the Motor Speed Error message. The graphs prove that there was a demonstrable issue with the prop's performance, and I wanted to know what caused that issue.

"No - you are speculating - plain and simple."

You do have a point there. I definitely am speculating. But my photos illustrate that my speculations are valid and logical, and I am confident that I'm on the right track. If you can prove me wrong, please do!

These data plots were from May 14th 2020. Since then I've stored my Mini with arms unfolded and the props never crossed. It has flown perfectly ever since and has never again triggered any of those warnings. I occasionally perform more Hover Tests and the motors continue to show a rock solid 9600 rpm while in a stable hover.

Far too many people are still seeing Motor Speed Errors. Far too many people are reporting that they've changed their propeller blades only for the error message to reappear shortly thereafter. How are you storing your prop blades?

I suggest to you, and everyone else here, do a Hover Test and plot your Motor Speeds, and then you'll know for certain whether your propeller blades are performing as they should. If they aren't, ask yourself why? Pay close attention to how you store the blades and what might be causing them to bend.

 

[maelstrom]

I never said, nor implied, that DJI is unconcerned about this issue. They have made numerous changes over the last year to improve the Mavic Mini, changes which prove that they are aware of the propeller deformation issue. They changed the warning messages from the original vague Max Power warnings, to more definite Motor Speed Error or Propeller Speed warnings, with explicit instructions to check or replace the affected propeller blades.

This is just as likely to be because the blades are easily damaged, rather than being deformed. Even blades of grass can cause minor damage to Mini blades. There’s no evidence to conclude that the changes to the Mini firmware were just because of blade deformation.