Propeller apparently broke off mid flight...

[PhantomWetSuits]

Hey this is coal from Phantomrain.org
So the video was a fantastic: Purely make the point that many have been claiming and that is that they did not forget to lock the props on. There are a lot of posts of people forgetting to lock in both clips on the battery , which happens all the time, many of them go unposted on this site. However the chances of forgetting to lock the props on are not likely and as your video show disaster happens quickly when the props are not locked in.

We noticed when testing are Phantom Rain Wet Suits in a collision with tree branches to see how the Wet Suit would hold up that the Props would just pop off sometimes and realized if we could lock the props on tighter the Phantom would have a much better chance at negotiating tree branches to get out of the way. We determined that the drone just needed a few more seconds to get out or harms way or go right through it. This is why we made the Phantom Rain Prop covers because they not only locked in the props but sealed out the rain from getting into the top of the motors.

That got us to looking at these props under a microscope and this is what we got, notice the second picture and see if you can see how that tiny knob has lifted up from what appears to be wear and tear or a weak knob.
We came to the conclusion that it was shaped slightly different making it more susceptible to slipping or lifting in this case.

Pay close attention to how thin those little knobs are and why we had to figure out a way to lock the props in using the Phantom Rain Prop Covers.

See pictures below. Most People thought they were just groves that went all the way down, but that is not the case.

The surprise for us was that the knobs were cut a little differently and were much thinner than we thought
We would have never seen this had we not been looking at finding a way to keep the props from coming off on impact.

 

[Timinator]

Interesting observation PhantomWetSuits. I wonder if this is the main reason behind the 50 flight recommended lifespan for props as opposed to any breakdown of the prop blade.

 

[Harleydude]

Hey this is coal from Phantomrain.org

Hello Coal.

So the video was a fantastic: Purely make the point that many have been claiming and that is that they did not forget to lock the props on. There are a lot of posts of people forgetting to lock in both clips on the battery , which happens all the time, many of them go unposted on this site.

I actually owned my P4P for 2 weeks before flying it. I researched everything from firmware to software to hardware. I wanted to see why guys were crashing and what the points of failure were. A misinstalled battery seemed to be one of the top culprits. In fact, it may have been your video I saw. And, yes, you are right on the money. I always make sure to double lock both the upper and lower battery tabs before every flight. It's habit now. I trained my business partner to do the same thing.

However the chances of forgetting to lock the props on are not likely and as your video show disaster happens quickly when the props are not locked in.

Exactly. I only showed 3 take off attempts, but I actually tried over a dozen times to make the prop stay on while not locked in. Not once did the prop give a false sense of security. The prop flew off every time. I'm sure this is the reason for the "double rev" at motor start. It's either locked in or not. There is no in between.

We noticed when testing are Phantom Rain Wet Suits in a collision with tree branches to see how the Wet Suit would hold up that the Props would just pop off sometimes and realized if we could lock the props on tighter the Phantom would have a much better chance at negotiating tree branches to get out of the way. We determined that the drone just needed a few more seconds to get out or harms way or go right through it. This is why we made the Phantom Rain Prop covers because they not only locked in the props but sealed out the rain from getting into the top of the motors.

Interesting.

That got us to looking at these props under a microscope and this is what we got, notice the second picture and see if you can see how that tiny knob has lifted up from what appears to be wear and tear or a weak knob.

Ahhhh...yes. I had to look at it for a few seconds. I think I would call that a "tab" as opposed to a "knob." But yes, I see your point.

We came to the conclusion that it was shaped slightly different making it more susceptible to slipping or lifting in this case.

Pay close attention to how thin those little knobs are and why we had to figure out a way to lock the props in using the Phantom Rain Prop Covers.

See pictures below. Most People thought they were just groves that went all the way down, but that is not the case.

DJI may have engineered in a "point of failure" on purpose to save the motor shaft. This is a common design in any motor/load situation. However, DJI may have shot themselves in the foot by making the POF TOO weak. That said...

My Mavic Pro has essentially the same locking system. But, unlike the P4P, I never remove the props. I just fold them. So the Mavic locking system never sees wear from R&Ring. THAT said... My P4P props had roughly 20 flights on them, 30 tops. I purchased the P4P specifically for a mapping gig (automated waypoint flying). So I test flew the bird via joystick like 5 or 6 times (shakedown test). I then ran a few automated waypoint test missions - roughly 5 or 6. And then we got out to the job site, and I completed < a dozen missions. I found a bug in the Map Pilot software that caused me to refly a couple sections....but that's another conversation for another time. Bottom line, there are less than 30 flights on those props. I HATE losing a brand new bird like that. But I digress...

The surprise for us was that the knobs were cut a little differently and were much thinner than we thought
We would have never seen this had we not been looking at finding a way to keep the props from coming off on impact.

Interesting. I'd bet dollars to doughnuts the prop was engineered that way on purpose to save the motor shaft in a sudden-stop/high-rpm situation. It's S.O.P. to design motor/loads with a point of failure to save the motor and/or motor shaft from bending. However, I concede that if the prop is failing mid-flight for no apparent reason, then clearly DJI has make the point of failure TOO weak.

We'll see what DJI says. I sent support the .DAT file and have yet to hear back. We'll see what they say.

Thoughts?

 

[PhantomWetSuits]

I have to agree on your assessment Harleydude : Its spot on and yes tabs are a better word and DjI must have made them to fall off on any kind of impact with that design on purpose most likely. So one thing that was not mentioned was which firmware you were using as we skipped on the one that caused the vibration in the drone, however many reported surface cracks and if that is the case with that kind of vibration happening could certainly be the cause of a prop wearing quickly. So maybe check into that also when you report to DJI as they may be checking for that themselves already. We also are aware that many have switched to the screw on props for this reason alone but we feel the Prop Covers we use are a better option.
Keep us posted on what they say. What you are hoping for is 100% coupon from DJI to purchase a new Unit. DJI is not a bad company as we have had two fly aways and they replaced both phantoms 4 pros with 100% coupons , but it takes time, so prepare for a lot of emails, each email response back and fourth will be 1 full day, this is annoying but there practice but after 30 days you should be getting there answer.

I almost forgot , if you have have an old prop , take your finger nail and lift one of the tabs off or break it off and put the prop back on and see what happens with only 2 tabs on. Just an idea.

 

[Timinator]

Interesting observation PhantomWetSuits. I wonder if this is the main reason behind the 50 flight recommended lifespan for props as opposed to any breakdown of the prop blade.

Will exposure to air make the plastic more brittle over time? Is this why the prop hubs are sealed in plastic from the factory and DJI recommends not removing it until you are ready to use the prop?

 

[PhantomWetSuits]

Interesting observation PhantomWetSuits. I wonder if this is the main reason behind the 50 flight recommended lifespan for props as opposed to any breakdown of the prop blade.

With out any doubt , this is the weakest link, and seeing that the tabs were so thin that would make sense on the 50 flights . What we found is that many of the crashes that happen take place on light impact when the props do fall off and so finding a way to keep them from falling off was important , but as mentioned you risk damaging the motor housing , but you also risk your drone dropping to the ground so it seemed the better option to lock them in tighter and the prop covers were a perfect solution to protecting them and making them stronger. We used 1.5mm covers made of Closed Cell Neoprene with a 3m backing , see picture below. The Top ring is the prop cover and its used to compress the prop tighter and the bottom ring is to create a roof for the two vents to stop water from getting inside the honeycomb structure inside.

 

[Timinator]

In the second picture with the deformed tab, did that come off an a motor that had the wet suit?

 

[PhantomWetSuits]

Will exposure to air make the plastic more brittle over time? Is this why the prop hubs are sealed in plastic from the factory and DJI recommends not removing it until you are ready to use the prop?

That is a great question and I for one hate the plastic, Its not so easy to get off in a hurry. That plastic is really and odd piece to the puzzle and I do not think it is for anything more than protection for the tabs. Its the only thing that makes sense but that is kind of a mystery as to why they do that. Somebody else might know but seeing that they are more fragile that most of us thought, you could be right.

 

[PhantomWetSuits]

In the second picture with the deformed tab, did that come off an a motor that had the wet suit?

No that was before the Wet Suit , the Neoprene covers those tabs to protect them from any kind of wear so you have Plastic touching neoprene touching plastic. that is the equation that works so well to keep the props locked on and fully protecting the motors

 

[Harleydude]

I have to agree on your assessment Harleydude : Its spot on and yes tabs are a better word and DjI must have made them to fall off on any kind of impact with that design on purpose most likely.

In your vast experience, have you had props fail mid-flight for no apparent reason? I flew Phantom 1's for about 2 years with nary an issue. And I have over 50 hours on my Inspire with zero prop issues. I think I'm on my third set of props with that bird. They just seem to get little nicks and burrs after a hundred or so flights, so I replace them and archive the old props as backups - but I digress...

I'm curious to know if you or anyone you know has experienced what I experienced.

So one thing that was not mentioned was which firmware you were using as we skipped on the one that caused the vibration in the drone,

I researched my firmware carefully. Finding the exact right firmware is a balance between "features" and "problems." After much research, I settled on the following:


App: v4.0.8

Aircraft: v1.3.509 Original: v01.01.0203

Remote: v01.04.01.00 Original: v01.03.00.00

The "original" are the versions the bird was shipped with.

however many reported surface cracks and if that is the case with that kind of vibration happening could certainly be the cause of a prop wearing quickly.

I inspect my props pretty much every time I use them. Again, this is habit. I'm a very observant person by nature. So even the slightest cracks or burrs are usually noticed rather quickly.

So maybe check into that also when you report to DJI as they may be checking for that themselves already.

At this point I have sent them the .DAT file and am waiting to hear back. In my mind, the .DAT file is pretty conclusive that the prop ejected for no reason. I'm sure it's compelling enough that they will ask me to ship the bird to them. By pure dumb luck, the failed motor (right-rear) suffered zero damage in the subsequent crash. It's easy to see that the hub and motor are completely undamaged with no noticeable wear on the locking hub (see close up photos in the OP). At the very least, I hope to be offered a replacement bird at cost. The only reason for this would be that "propellers" are specifically mentioned in the DJI warranty as "not covered." However, that said, if the **** things are failing mid-flight for no reason, I'm sure DJI will step up. We'll see.

We also are aware that many have switched to the screw on props for this reason alone but we feel the Prop Covers we use are a better option.

If you're allowed, please provide a link to them.

Keep us posted on what they say.

Will do.

What you are hoping for is 100% coupon from DJI to purchase a new Unit.

Not a whole new kit. I'm hoping they'll ship a replacement drone...or re-certify the one that crashed. But as you can see in the photo, it was damaged pretty good. The camera glass is scratched and the camera no longer transmits a video signal. I haven't tested to see if it records video or not.

DJI is not a bad company as we have had two fly aways and they replaced both phantoms 4 pros with 100% coupons...

That's good to know. They replaced/upgraded my NAZA unit when my Phantom 1 prop spun off. This was before the reverse thread, self-locking props. Back then, they were self UNlocking.

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...but it takes time, so prepare for a lot of emails, each email response back and fourth will be 1 full day, this is annoying but there practice but after 30 days you should be getting there answer.

Thanx for the heads up. Good to know. I honestly don't see any ambiguity in my case. It's pretty darn obvious what happened. All the proof is right there in the data files. Clearly, one can see that the drone flew a grid pattern for 6 minutes, and then at 200+ feet AGL, the right-rear motor spins up to 13K RPM and the drone falls to the ground. There were no trees or buildings or power utilities for hundreds of yards. It would be tough to draw any other conclusion other than prop failure.

I've parked the .DAT file on the cloud if you want to look at it.

DJI - Google Drive

I almost forgot , if you have have an old prop , take your finger nail and lift one of the tabs off or break it off and put the prop back on and see what happens with only 2 tabs on. Just an idea.

You know, if I get anything out of this thread, it's going to be to closely inspect the propeller hubs occasionally. It seems I don't have to pull back the tabs, as it seems the crash may have done that for me. Check out these photos:

Crash survivor - Prop 1:

Crash survivor - Prop 2:

FWIW, one of these is the prop I used in my test. While I certainly wouldn't want to FLY on these props, they did pass the spin-up test in the living room.

Great thread. Thank you for your contribution!

D

 

[PhantomWetSuits]

Those pictures do show rather well that the plastic is prone to some wear but those tabs are still in place. You can get the Prop Covers from are website Phantomrain.org. I will also take a look at the Dat file, thank you.

 

[Timinator]

No that was before the Wet Suit , the Neoprene covers those tabs to protect them from any kind of wear so you have Plastic touching neoprene touching plastic. that is the equation that works so well to keep the props locked on and fully protecting the motors

Ah ok. I was thinking if there was additional pressure on the locking mechanism if that would eventually cause the tab to deform under heat/pressure but that's not the case if it came from a non-wet-suited aircraft.

 

[Timinator]

In your vast experience, have you had props fail mid-flight for no apparent reason? I flew Phantom 1's for about 2 years with nary an issue. And I have over 50 hours on my Inspire with zero prop issues. I think I'm on my third set of props with that bird. They just seem to get little nicks and burrs after a hundred or so flights, so I replace them and archive the old props as backups - but I digress...

I'm curious to know if you or anyone you know has experienced what I experienced.






I researched my firmware carefully. Finding the exact right firmware is a balance between "features" and "problems." After much research, I settled on the following:


App: v4.0.8

Aircraft: v1.3.509 Original: v01.01.0203

Remote: v01.04.01.00 Original: v01.03.00.00

The "original" are the versions the bird was shipped with.








I inspect my props pretty much every time I use them. Again, this is habit. I'm a very observant person by nature. So even the slightest cracks or burrs are usually noticed rather quickly.






At this point I have sent them the .DAT file and am waiting to hear back. In my mind, the .DAT file is pretty conclusive that the prop ejected for no reason. I'm sure it's compelling enough that they will ask me to ship the bird to them. By pure dumb luck, the failed motor (right-rear) suffered zero damage in the subsequent crash. It's easy to see that the hub and motor are completely undamaged with no noticeable wear on the locking hub (see close up photos in the OP). At the very least, I hope to be offered a replacement bird at cost. The only reason for this would be that "propellers" are specifically mentioned in the DJI warranty as "not covered." However, that said, if the **** things are failing mid-flight for no reason, I'm sure DJI will step up. We'll see.






If you're allowed, please provide a link to them.








Will do.






Not a whole new kit. I'm hoping they'll ship a replacement drone...or re-certify the one that crashed. But as you can see in the photo, it was damaged pretty good. The camera glass is scratched and the camera no longer transmits a video signal. I haven't tested to see if it records video or not.






That's good to know. They replaced/upgraded my NAZA unit when my Phantom 1 prop spun off. This was before the reverse thread, self-locking props. Back then, they were self UNlocking.

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Accept third party cookies

Thanx for the heads up. Good to know. I honestly don't see any ambiguity in my case. It's pretty darn obvious what happened. All the proof is right there in the data files. Clearly, one can see that the drone flew a grid pattern for 6 minutes, and then at 200+ feet AGL, the right-rear motor spins up to 13K RPM and the drone falls to the ground. There were no trees or buildings or power utilities for hundreds of yards. It would be tough to draw any other conclusion other than prop failure.

I've parked the .DAT file on the cloud if you want to look at it.

DJI - Google Drive






You know, if I get anything out of this thread, it's going to be to closely inspect the propeller hubs occasionally. It seems I don't have to pull back the tabs, as it seems the crash may have done that for me. Check out these photos:

Crash survivor - Prop 1:

View attachment 96518


Crash survivor - Prop 2:

View attachment 96519

FWIW, one of these is the prop I used in my test. While I certainly wouldn't want to FLY on these props, they did pass the spin-up test in the living room.

Great thread. Thank you for your contribution!

D

If only you had the missing prop. This might be one of those cases where a ground search for it really would be worth it. Learning how and why that prop detached from the aircraft is crucial. There's got to be cracking or outright separation somewhere around the prop hub for it to detach so cleanly.

Quite honestly, loss of flight like this scares me. Most of my flying is over the lake or shoreline so I make triple sure my props are on securely and are in good shape but something like this I don't know if I could plan for this.

Can't recall if you mentioned what the air temp was at the time of the crash? Was it below freezing and would this prop have been stored in say a truck or some other outdoor cold place?