It happened again - prop failure #2...

[Harleydude]

Hey doods;

So it seems it happened again...same problem, same conditions...

Deja vu for me....on a mapping mission this afternoon, I had a prop break mid flight. However, this time I have the prop. It seems this time, instead of the prop hub breaking, only one of the two rotors broke off the hub. So technically, I didn't lose a propeller. I only lost HALF a propeller.

Other than using my Phantom 4 an order of magnitude more than most guys, I'm doing nothing wrong.

So, once again I'm going to ask if any of you guys have seen prop failure. That's really the only information I can use at this point. Or if there are any plastics experts out there, perhaps they can look at the photos of the broken prop and share your thoughts.

Worth noting; the remaining 3 props remained essentially intact. One prop ejected upon impact. I know this to be true because the prop was a mere 8 feet from the drone (as opposed to 200' away had it ejected @ 300').

I've submitting an RMA to DJI. I purchased the Care Refresh for the replacement drone, which lasts a year from the purchase date mere weeks ago. The *warranty* ends May 10th. HA! So one way or the other, this will be replaced. Hopefully, sooner than later.

It's hard to believe this hasn't happened a second time...especially after DJI assured me it wouldn't.

Another thing worth noting, is that I notice the P4P props have the slightest amount of wiggle room on the hub. I can kind of rotate the prop 1° on the hub. They do the same on the Obsidian hub.

The Obsidian props, however, have zero tolerance. They are very tight on the hub. I think I'm going to purchase Obsidian props from now on.

D

 

[Florida Drone Supply]

Wow, that is crazy! Do you know how many hours you have on that set pf props?

 

[Harleydude]

Wow, that is crazy! Do you know how many hours you have on that set pf props?

The bird and props were new. I had flown maybe 4 jobs and a few test flights. 3-4 hours total flight time on the bird and props??

D

 

[Florida Drone Supply]

The bird and props were new. I had flown maybe 4 jobs and a few test flights. 3-4 hours total flight time on the bird and props??

D

I hope for a speedy repair or replacement for you.

 

[RunningWithScissors]

It's hard to believe this hasn't happened a second time...especially after DJI assured me it wouldn't.

Your experience is likely the first on record. Sorry to hear you've lived through this nightmare twice.

 

[Just_nick]

I've never seen that.

 

[Harleydude]

Your experience is likely the first on record. Sorry to hear you've lived through this nightmare twice.

Thank you, sir. I have a big job next Thursday (May 10th). It would be nice if I had my drone back by then. I also ordered Obsidian props. For whatever reason, they are made to a tighter spec', which *hopefully* means better quality.

 

[Timinator]

Oh man! Oh Man Oh Man oh MAN!!!!!!!!!!!

 

[Harleydude]

Oh man! Oh Man Oh Man oh MAN!!!!!!!!!!!

My thoughts exactly as I watched the little, red icon spin, spin, spin....

 

[BigAl07]

Talk about CRAPPY luck . . . Remind me to NOT take the same planes you take when traveling LOL.

I'm anxious to hear what DJI has to say about this 2nd failure.

 

[Timinator]

Have you looked at any of the remaining props to see if there is any cracking in the hub? It appears to have broken at the leading edge.

 

[Harleydude]

Talk about CRAPPY luck . . .

Honestly, I think this is a QAQC issue....or perhaps a design flaw. If you think about it, mapping is pretty hard on a bird. It flies all day, back-to-back mission at an average speed of 25 mph, with RTH set to 33 mph. We have 6 batteries and 2 chargers that charge 3 batteries simultaneously. So with all that, we can pretty-much keep the bird in the air all day. So, though I don't have a lot of flight hours on the birds, they are fairly hard hours. With more speed comes more dynamic load on the rotors, especially on days when wind gusts hit 20-25 mph. I simply think the props are made cheaply and are therefore failing under these demanding loads. Because me and my partner are at the bleeding edge of mapping technology and working a LOT, I just think we're seeing failure where most pedestrian pilots are not.

Remind me to NOT take the same planes you take when traveling LOL.

I know, right?!

I'm anxious to hear what DJI has to say about this 2nd failure.

I will definitely keep you guys in the loop.

 

[Harleydude]

Have you looked at any of the remaining props to see if there is any cracking in the hub? It appears to have broken at the leading edge.

I started inspecting the props daily. This is a very comprehensive inspection that concentrates on the hub area. I even stick my fingernail and pull on all 3 tabs in each of the 4 hubs. Pre-flight checks have shown the props to be in excellent condition. That said....

I have noticed that there exists some play in the P4P props that does NOT exist in the Obsidian props. The motor hubs on the P4P and Obsidian are exactly the same, but the PROPS appear to be different in fit and form....hmmmmm.... So...I have ordered a set of Obsidian props for my next replacement P4P.

 

[BigAl07]

Donnie I think you've hit the nail on the head. Mapping is a "balls out" type of flying and yes you're pushing the sUAS beyond it's intended design capacity. I think that's exactly what you're seeing here.

 

[Timinator]

I started inspecting the props daily. This is a very comprehensive inspection that concentrates on the hub area. I even stick my fingernail and pull on all 3 tabs in each of the 4 hubs. Pre-flight checks have shown the props to be in excellent condition. That said....

I have noticed that there exists some play in the P4P props that does NOT exist in the Obsidian props. The motor hubs on the P4P and Obsidian are exactly the same, but the PROPS appear to be different in fit and form....hmmmmm.... So...I have ordered a set of Obsidian props for my next replacement P4P.

So perhaps there is vibration occurring in the gap which is causing fatigue cracking almost like a jackhammer to concrete.

 

[RunningWithScissors]

@Harleydude,
In looking at the second photo, I'm seeing a whitish area on the remaining blade that looks like it may be stress related (or not). Can you comment on what may have caused caused that?

 

[Bakersfield Quad]

I would get a can of dye and spray for finding cracks in things, then check my blades routinely. I haven't seen this type of failure, nor have I seen it shown online before, seems rather odd.

 

[Harleydude]

Donnie I think you've hit the nail on the head. Mapping is a "balls out" type of flying and yes you're pushing the sUAS beyond it's intended design capacity. I think that's exactly what you're seeing here.

I think "beyond design capacity" isn't exactly correct. We're seeing prop failure, NOT drone failure. I have 100% confidence that, without the crappy prop issue, these P4P's would fly very reliably for many hours. I have almost 50 hours on my Inspire and she flies like the day I purchased her. The motors and gimbal (essentially the only moving parts) still feel and work like new. Even the worm gear assembly still works like new. According to a DJI lemming, the motors are tested and rated to 1000 hours.

Others have argued that the bearings should be replaced @ 100 hours, but I've yet to see any documentation to support that assertion. And I've yet to see any motor bearing failures. I HAVE seen some guys with motor failure, but they are warned ahead of time with over-current warnings in the DJI Go App, which they duly ignore. So SOME motors are flawed. But I believe if a motor makes it past 10 hours that it will last for over 100 hours.

I've been flying quadcopters since 2010, and I've yet to see a single brushless motor failure. YMMV.

I have a feeling the answer to this conundrum is going to be the Obsidian props. Clearly, they fit better, which tells me there's more difference than just color.

If I DO find that the Obsidian props are more reliable (or if they're not), you can bet I'll make a video about it.

D

 

[Harleydude]

I would get a can of dye and spray for finding cracks in things, then check my blades routinely. I haven't seen this type of failure, nor have I seen it shown online before, seems rather odd.

I hear what you're saying. The kind of inspection you're talking about is done well at home under good lighting (which I do before every job), but when I'm out in the field trying to beat the wind on the top of a hill, I honestly can't take time to conduct comprehensive inspections of every rotor after/before every flight.

My solution, for now, is going to be to use the Obsidian props. There's a clear difference in fit and form. Where the P4P rotors have "slop" with the motor hub, the Obsidian props fit very tightly. Methinks the perpetual change in motor RPM may be causing the "sloppy" props to "bang" to and fro on the motor hub. This may be causing plastic fatigue in the prop's hub (which is where I'm seeing failure). Conversely, the tight-fitting Obsidian props wouldn't have that issue because there's no "slop." So I'm going to give that a shot. I guess we'll see if that works.

 

[RunningWithScissors]

Methinks the perpetual change in motor RPM may be causing the "sloppy" props to "bang" to and fro on the motor hub. This may be causing plastic fatigue in the prop's hub (which is where I'm seeing failure).

Methinks you may be on to something there that the rest of use could (or already have) experience eventually. Because of how you're using your Phantom, maybe you're seeing it sooner than the rest of us. Definitely something to watch.