Mid-flight propeller failure - mystery solved....

[Dpanetta]

When it comes to tech, I live by one rule. If it ain’t broke, don’t fix it! That same mindset has saved me a lot of grief with all the DJI, iPad, and iPhone software/firmware updates too! I have not updated my iPhone to the latest firmware yet following that rule, and for good reason. Lots of negative reports about Bluetooth not working after the update. Since I use NFC for file transfers often , this rule has again paid off for me.

But I do agree that I am lucky in that my props have lasted so long. As part of my preflight tests, I measure the flexibility of my props with a fixed weight. From day 1 to present, the props have stayed well within the plastic fatigue test limits of good plastic resins. Say what you want about DJI software, but the plastic they use in their prop construct is very good (at least, for the set of props I got in my P4 over a year ago it was).

Now if I were really serious about a UAV staying aloft, I would have never considered DJI in the first place. There are other UAVs on the market that have 5, 6, or more props. And some of them can survive loosing a prop or motor in mid flight. But I don’t have $3k+ to drop on one of those.

 

[N017RW]

Don’t know hours or flights but my P2-NV props are about 3.5yrs old.

Not concerned about their condition until they strike something other than air or bugs.

 

[Clockman]

Hey doods!

This is the final in a series of threads regarding my mid-flight propeller failures (yes, plural). If a picture is worth a thousand words, a video is worth 10x that.

Hopefully, this video prevents any of you from experiencing the same problem.

Warning: FAA trolls, save it. Your non-contributing, non-helping comments will be deleted.

D

These drones are not like RC helicopters and airplanes. As you said the the props are spinning at 3000 to 5000 RPM....BUT.... they are constantly changing speed to complete turns and changes in altitude. This puts a lot of stress on the props and the motors. Anyone who has a Phantom 3 with cracks in the shell around where the motors mount can attest to this. Probably best to buy your props from a reputable dealer (meaning not EBAY).

 

[Harleydude]

Your second drone was a DJI replacement - did they ship the drone with aftermarket props or did you swap the ones that came with the replacement with another set at some point?

They shipped BOTH drones with NO props. So, yes, drone #2 got another set of aftermarket props. Rest assured, drone #3 is donning OEM props ONLY.

Did a small, 40 acre mapping job a few days ago with zero issues.

D

 

[Harleydude]

Don’t know hours or flights but my P2-NV props are about 3.5yrs old.

Not concerned about their condition until they strike something other than air or bugs.

Up until these last P4P incidents, these were my thoughts exactly. My Inspire props and Mavic props have dozens of hours on them. And until they strike something, they're staying on there.

D

 

[Stimmy]

When it comes to tech, I live by one rule. If it ain’t broke, don’t fix it! That same mindset has saved me a lot of grief with all the DJI, iPad, and iPhone software/firmware updates too! I have not updated my iPhone to the latest firmware yet following that rule, and for good reason. Lots of negative reports about Bluetooth not working after the update. Since I use NFC for file transfers often , this rule has again paid off for me.

But I do agree that I am lucky in that my props have lasted so long. As part of my preflight tests, I measure the flexibility of my props with a fixed weight. From day 1 to present, the props have stayed well within the plastic fatigue test limits of good plastic resins. Say what you want about DJI software, but the plastic they use in their prop construct is very good (at least, for the set of props I got in my P4 over a year ago it was).

Now if I were really serious about a UAV staying aloft, I would have never considered DJI in the first place. There are other UAVs on the market that have 5, 6, or more props. And some of them can survive loosing a prop or motor in mid flight. But I don’t have $3k+ to drop on one of those.

If we were to adhere by that principle then I guess preventative maintenance of aircraft shouldn't be a thing. We shouldn't wait for an object to fail, we should prevent it from failing in the first place. I wouldn't fly on an airplane whose techs worked by that motto.

If it ain't broke don't fix it is a decent motto for land bound objects. For 20 bucks is it really breaking the bank?

 

[Harleydude]

These drones are not like RC helicopters and airplanes. As you said the the props are spinning at 3000 to 5000 RPM....BUT.... they are constantly changing speed to complete turns and changes in altitude. This puts a lot of stress on the props and the motors. Anyone who has a Phantom 3 with cracks in the shell around where the motors mount can attest to this. Probably best to buy your props from a reputable dealer (meaning not EBAY).

I found an eBay vendor who sells OEM props. I purchased two complete sets (8 props total) of Obsidian props from him @ roughly $7.00/prop, which is NOT a "deal." So, yeah, I'll be buying directly from DJI from now on - especially now that they take Paypal.

D

 

[N017RW]

I guess it comes down to personal experience.
Been flying r/c since the early 70s and never had a prop or blades fail in-flight.

TEHO

 

[Harleydude]

If we were to adhere by that principle then I guess preventative maintenance of aircraft shouldn't be a thing. We shouldn't wait for an object to fail, we should prevent it from failing in the first place. I wouldn't fly on an airplane whose techs worked by that motto.

If it ain't broke don't fix it is a decent motto for land bound objects. For 20 bucks is it really breaking the bank?

I don't think Dpanetta's paradigms preclude maintenance. I apply this paradigm to updates and/or "improvements" (HUGE air quotes there). I may not change the BRAND of oil I use, but I sure as hell change my car's oil at regular intervals. I'm pretty sure this is what Dpanetta meant.

D

 

[Stimmy]

I don't think Dpanetta's paradigms preclude maintenance. I apply this paradigm to updates and/or "improvements" (HUGE air quotes there). I may not change the BRAND of oil I use, but I sure as hell change my car's oil at regular intervals. I'm pretty sure this is what Dpanetta meant.

D

I understand what you are saying. But with 700 hours on a set of props aren't you just waiting for something to go wrong at that point?

Updates are and improvements are exempt because they are software based, and who knows if they live up to their promises until they are tried and true.

But hardware such a prop? Those have a lifespan. Replace them after X amount of hours (not 700). Because if we use your basis of comparison of car oil with Dpanetta's methodology then you haven't changed your oil in 50000 miles.

Maybe you could clear up what you meant Dpanetta?

 

[Dpanetta]

Well, if you are using oil changes as a comparison, are you talking about your gasoline powered 1976 Chevy Malibu, or are you talking about your new diesel Mercedes using a synthetic blend motor oil?

It really depends on the wear and tear of the product. I do not go nuts wit high speed maneuvers with my P4. Besides, I don’t consider a maximum speed of less than 50mph very “high” anyway. If I want speed, I will drop $300 on a racing drone that can top out close to 100mph.

Oh, and to the people saying that they would only replace the props if they have an impact, I would rethink that. The UV rays of the sun can take a serious toll on plastic and rubber. The plastic can develop micro stress cracks that are undetectable to the naked eye. Only a microscope or a flexibility stress test can detect that in props. Keeping the props clean and wiping them down with a VERY light silicone after every day of flying helps extend the life of plastic products.

 

[Stimmy]

Well, if you are using oil changes as a comparison, are you talking about your gasoline powered 1976 Chevy Malibu, or are you talking about your new diesel Mercedes using a synthetic blend motor oil?

It really depends on the wear and tear of the product. I do not go nuts wit high speed maneuvers with my P4. Besides, I don’t consider a maximum speed of less than 50mph very “high” anyway. If I want speed, I will drop $300 on a racing drone that can top out close to 100mph.

Oh, and to the people saying that they would only replace the props if they have an impact, I would rethink that. The UV rays of the sun can take a serious toll on plastic and rubber. The plastic can develop micro stress cracks that are undetectable to the naked eye. Only a microscope or a flexibility stress test can detect that in props. Keeping the props clean and wiping them down with a VERY light silicone after every day of flying helps extend the life of plastic products.

So what would you say are the lifespan of dji props?

 

[Dpanetta]

Oh, and When I say if it ain’t broke don’t fix it, that includes stress cracks. I detect even one stress crack in the props or any part of the UAV, that part is getting replaced. Broke doesn’t mean that the prop broke off in my mind. Aviation mechanics and even private plane pilots check thier aircraft for stress cracks, oil leaks, compression blow by, and all sorts of things at regular intervals, and some before every flight as part of thier preflight checks. It doesn’t hurt to apply there level of maintenance checks to my UAV. Besides, it’s fun to dig so deeply into the mechanics of flying. Did you know that the P52 Mustang had serious propeller issues when they first took to the sky’s because the tips of the props were sheering off? It was because the tips were moving in excess of 740mph, and the vibrations created by breaking the speed of sound we’re wearing the prop tips down.

 

[N017RW]

You should operate in the way that makes you feel comfortable.

This does not mean it’s the same for everyone. My experience conflicts with your feelings.

In times of conflict I usually side with my experiences over those of others.

 

[Dpanetta]

So what would you say are the lifespan of dji props?

If you go by the forums or even the DJI Care Refresh program, that would be around 200 flights. But if you are a radical flyer, or leave the drone in the sun often, that time WILL be considerably less. On the flip side, if you are a conservative flyer, care for your drone keeping it clean, no hard turns or maneuvers, and no impacts to the props (like me) then that time can be extended.

 

[Dpanetta]

You should operate in the way that makes you feel comfortable.

This does not mean it’s the same for everyone. My experience conflicts with your feelings.

In times of conflict I usually side with my experiences over those of others.

I definitely agree with you there! If you are flying the way you like, then you are having fun doing it. If you want to push the stress limits of your drone, then do it! What good is flying if your not enjoying it? I have been looking into the next level of flying (at least in my mind anyway). Racing! Lots of options there, and the RTF ones don’t seem to be too fast. Going to enjoy building a drone from parts

 

[Stimmy]

If you go by the forums or even the DJI Care Refresh program, that would be around 200 flights. But if you are a radical flyer, or leave the drone in the sun often, that time WILL be considerably less. On the flip side, if you are a conservative flyer, care for your drone keeping it clean, no hard turns or maneuvers, and no impacts to the props (like me) then that time can be extended.

Assuming the max flight time of 30 min that's about 100 hours. So you're saying that flying conservatively can extend the life of the props 7 times that amount?

You sound very well versed in the matter though. So I guess if you feel comfortable that's all that matters.

 

[Bagotfish]

Hello, just wanted to thank you for the great information!
It’s wonderful to see pilots helping pilot stay in the air safely.

Thanks again, Rod in Alaska

 

[drvrbobob]

But Donnie.. porn doesn't count LOL!

(J/K Donnie is a good friend of mine).

Well it should! LOL

 

[RunningWithScissors]

Yeah, and buy me a lotto ticket also. Wait, make that two tickets. Thanks. I'll pay you back after I win.