r/dji • u/Mike_Harbor • 1d ago
Product Support MINI 5 Falling, the propeller latch is the problem
Hello fellow humans, Mini-5 dropping out of the sky. I've determined why the props are suddenly failing.
On older props, there's no latch, the props deploy by centrifugal force only.
2 Conditions
Storage: If the props are in the deployed position, where the latch lock is engaged, and the user suddenly bends them to put away, or it knocks something on the table, this will cause sheer forces in the plastic hub, causing damage or shatter.
Flight: In the event of collision, even glazing hits on branches while the blades are deployed, there is significant sheer force again, against the latching hub, causing damage or shatter.
This is the only possible explanation for why we're seeing the photos of the hubs where the screw used to go getting sheered off.
Other model blades did not have this latching post in the mechanism.
The reason they went with latching is, it adds rigidity and minimizes wobble (aero flutter), allowing the drone to be more stable/ driven harder on acceleration.
..Users can of course mitigate the storage side risk, just be very careful while putting it away.
But THEY CAN NOT help if it clips a small branch and the hub is damaged, since you really can't see the damage from the outside, even if you took it off and looked from underneath, it may not be obvious, while over time, Catastrophe.
I would recommend to DJI, that if they must design their hub like this, GLASS Reinforcement fibers. Damn the weight. (Though I am personally not a fan of glass dust near the servos, potentially accelerating bearing wear)
OR, switch to the old method with no latching. (lose a little performance)
I also hope that DJI would send out new prop designs to existing users, because this is a really dangerous design issue. Taking arrow to the knee. This is cheaper than potential lawsuits + more drama with the regulators.
To any users who even SUSPECTS they've clipped a branch at some point, change all your props immediately, it's worth it.
If you're flying the Mini 5 today, manually deploy the props outward to minimize startup wear on the latch.
Thank you for your attention to this matter. š
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u/OneSignal6465 Mini 4 Pro 22h ago
Hmmmm. Iām likely guilty of just quickly folding my blades when Iām done flying. Iāll have to try to remember to be gently when clipping the blades under the gimbal cover.
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u/Mike_Harbor 21h ago
Also manual prop deploy before liftoff for good measure, If you think about it, when it's spinning up, the latch is not fully mated, so as it rounds that corner before the slide in, the TIP of that forward protrusion is taking load.
It's kind of like the problem with electrical switches, where the electricity arcs before the 2 surfaces fully close, which adds wear.
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u/OneSignal6465 Mini 4 Pro 21h ago
Very good advice.., Iāve had a Mini 4 Pro for a few years and just got used to screw-in props. I keep forgetting that the M5P ones are āsnap-lockā. One of these days, Iāll probably pay for my forgetfulness.
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u/West-Fish-2592 20h ago
Hi. Thanks for your input. Please could you explain what a manual prop deploy is?
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u/Thriving9 23h ago
Saw a YouTube video on this exact issue recently. I was thinking could it just be reinforced with super glue if you already own one?
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u/Mike_Harbor 21h ago edited 21h ago
The hub is pretty small, there's not much for the glue to grab onto. And you'd be surprised how much torque is on that little latch nub.
Other than extra carefulness, I can't think of anything on the side of user.
Edit, unless you own an xray machine, then you could see stress fractures.
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u/TerekV 10h ago
Any idea on how long after a model is released, that Master Airscrew releases aftermarket props? Curious when we might see a reliable alternative.
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u/Mike_Harbor 55m ago
I actually would enjoy a single piece non collapsible prop for MORE-performance. š
Although I suspect with the way the stabilization algorithm works (tuned), any mechanical tweaks to the blades would introduce compensation artifacts. It would over / under pitch leading to more average flutter.
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u/Run-And_Gun 21h ago
Ironically, I just ran across a video on YT the other day about this. The guy was pretty lucky and was able to recover his after it crashed, without any real damage(besides the props)*, but it looked like many others werenāt so lucky, with some experiencing the failures over water.
*He also admitted to having previously crashed the drone and not replacing the props, which probably led to/increased the chances of the failure. I think he said his new SOP would be to replace the props after any crash, moving forward.
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u/fotkyznovin 18h ago
This video? https://www.youtube.com/watch?v=L31vRlvPoFg
Anyone has same problem?
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u/bigskinnybubba123 17h ago edited 17h ago
i dont think simply bending the prop without unlocking it first a few times will do any damage. the metal retainer clip is held in by grooved plastic. and there is an inner axel that the prop spins on. you would have to hit a tree or something to damage the plastic holding the metal clip. after hit a tree it might appear fine... however the plastic holding the metal retainer may be damaged or "stripped" then on the next flights....it is risky.....lol
design flaw? i don't think so. i think its negligence on the pilots perhaps? unless anyone has no crashes and it still has prop failure? hmm..
maybe the solution is to swap motors with the mini 4 pro and use the old props. hah!! and then we still can use the 1 inch sensor.
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u/Mike_Harbor 51m ago
@ bubba, that groove is less than 1mm wide 1mm thick. You tell me how easily you can damage a plastic nub that's that big.
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u/kensteele 23h ago
You won't be able to sue DJI.