I bought a set of snap on prop guards from Bestem Arial a few weeks back a used them with my new graphite props this weekend. The first three flights went fine the fourth was a near disaster. I was descending from about 300 feet at a pretty good rate when I got to about 75 feet all of a sudden the bird took off to the left and started making a clicking sound. I could only slightly slow its decent for just a second with some control input then is dove the rest of the way down. It flew over the tops of two houses and I thought it was going to be in a bunch of pieces when I found it. When I did find it a High School kid was holding it and its motors were still spinning at a high rate. He had seen the crash and told be it came down with only three of it motors turning. The craft was in remarkably good shape, all the blades were ruined and some dirt was the only damage. I replaced the blades and it fired right up.

What I feel happen was that one of the prop guards had broken and because it was in a decent pushed up into the prop. There was one of the prop guards with a middle support arm broken off at its root where it snaps into the Phantom by the prop. This I feel let it push up into the prop.

I was worried about how well these prop guards were made, they seemed pretty flexible and cheap but I had seen a lot of people were using them apposed to the ones sold by DJI because they still fit in the case since you can take them off. Maybe I just bought a bad brand if I could get some input from the forum as to what would be a good buy for quick release prop guards I would really appreciate it.

Thanks

The prop guards you linked to only have two mounting fasteners. Is it possible that the screws weren't tight and allowed the guard to pivot up when you rapidly descended? Also you might not have had  the guard completely snapped into place.

How about some pictures?

I will post a picture of the broken guard. I made sure they were snapped in right I did see when I first put them on they could go on wrong. I will check the screws too when I get home but I had just installed them so I'm pretty sure they were good and tight.

I use the DJI guards mounted to quick release cups that slide over end of arms and snap into motor mount holes. No issues so far.

P3PO Posted at 2015-9-8 09:41
I use the DJI guards mounted to quick release cups that slide over end of arms and snap into motor m ...

Sounds good, could you send me a link as the where to get the cups. I have the DJI guards I haven't used them because they wont fit in the case unless you take them off.  

only and ever time dji approved accessories especialy props and guards buy cheap buy twice plus in this case

Prop Guards add mass to your DJI3 which creates drag in flight.  The drag is exaggerated when your DJI is descending at a high vertical speed which also induces Vortex Ring State.  This all adds stress to the airframe and your prop guards.  Its possible your flight experienced Vortex Ring State on the descent and the prop guard/s or attachment/s could not accept the additional stress and failed in flight.  For those pilots who would like to see this additional stress, just climb to 200 feet or more and then descend straight down with the throttle stick in the extreme down position.  You will see your DJI shake  and vibrate!   When you've seen enough just decrease your descent and fly forward while descending to stay out of Vortex Ring State.