DJI Drone Help Forum

P2V Crash Report


#1

Thought I’d describe my crash for the good of the community.

I’ve had this AC since 2015 and logged over a thousand miles with it. I’ve had one catastrophic crash where the AC lost a prop and dropped from 400 feet. I attribute it to not checking the tightness of the props before flight. Lesson learned.

It’s been a long time since I’ve had a hard crash - about two and a half years.

Started out with air temp 30 F heading NNW 330 with a tail wind of about 10 mph at 400’. I’m not afraid of flying with a tailwind as I’ve done it 100 times. Fly out high, fly back low.

Pretty sure a prop developed a crack because the AC began to shake more than it should about 90 secs into the flight. It was smooth at first and then suddenly began shaking. If you have ever had a P2V, you know what I mean as the gimbal is pretty weak. You can see any kind of unusual vibrations, such as coming straight down in the VRS cone or flying through unusually violent wind gusts. I considered turning around but didn’t. I thought maybe it was just gusty winds but at the same time knew it wasn’t really that windy. Then after less than a minute it suddenly turned sideways and showed me a perfect 90 degree horizon and I lost signal. The FPV image on my app was frozen at 90 degrees.

Trackimo wasn’t much help finding it as the last fix was almost a half mile back and it wouldn’t update for me. But luckily the last location was very accurate from the DJI telemetry and I had google maps on the app. So I knew exactly where it dropped. It was easy to add a little bit for forward motion and the tail wind. So I drove off into the farmland. I had to take some back farm roads which I wasn’t happy about, but it was too deep into the farm area to park on a county road and walk through the snow which is still on the ground from the storm nine days ago. I found it. It was pretty much exactly where I thought it would be. Ground is frozen as we haven’t been above freezing in three days. It was on the edge of a tree line so it might have hit a branch on the way down. Not sure.

Turned out, trackimo had turned itself off on impact. I believe the trackimo hit the ground first. It was still mounted on the leg and it was twisted all around facing the other way, so I think it absorbed a lot of the impact and the impact shut if off. Marvelous. That’s just what you need for a drone tracker - have it shut off after a crash. But still - Trackimo boots up and still seems to work.

All four props were on the AC but two of them were broken. Legs weren’t broken or even cracked. Neither were the AC wings or anything else on the shell. I don’t even see any scrapes. Seems impossible. Camera came off of course. Modded FPV antennas and cables didn’t fare well.
But gimbal arms aren’t broken either. Not sure if camera survived but it seems to boot up ok.

Bottom line is there isn’t really a lot of obvious brutal damage. I need to check it further. AC didn’t boot up correctly but it did power up. There’s a receiver plug hanging out of the clam shell with the cable being pinched. Obviously the clam shell opened and closed very quickly and very violently upon impact and yet somehow doesn’t show damage. Got some video but only 2 and a half mins, didn’t get to the part where it fell. I think the file fixed itself but I lost the last min or so which is typical after a crash.

I’m going to blame this crash on the aftermarket props which I had previously held in high regard. Those are the master airscrew props. I think they are a little bit more stiff than stock which I think contributed to the crack and break. I think the cold weather, 30 F, caused one of the props to crack and then break. There was no sign of a problem until after I was well into the flight. I haven’t had any crashes or hard landings with these props, so I can only suspect the MA props cracked and broke due to the cold. I’m going to do a freezer test in a day or two and compare MA and stock.

The AC landed at a tree line between two farm fields. I was hoping I could get in and out undetected but the farmer saw me and drove out in his huge tractor out when he saw my vehicle on his farm road even though I stayed back in the woods. He said “Are you the one that flies overhead every other day?” I hung my head and said, yessir. Told me I should have asked him first and that it’s private property. By that time I was holding the drone in my hands and I had apologized and then he said “sorry about your property”, something like that. He didn’t seem too angry. Could have been worse.

Battery has a crack in it but otherwise seems okay. I found it about 20 feet from the drone. It starts up fine still. I will try to fix the crack. It’s a really good v2 battery. Most P2 owners don’t even know these exist.

I’m 100% sure this AC is fixable, although I admit there aren’t many original parts left. Centerboard, one motor/ESC assy, gps module, and top gimbal bracket. And a few cables. That’s all that’s left of the original before this crash. But this AC will fly again.

In summary: IMO, be wary of Master Airscrew props in the cold.


#2

Thanks for sharing your story!

I’ve been seeing a lot of people recommend these lately (for various DJI drone models). I don’t see the benefit in switching to them since DJI props usually work very well. A majority of the broken prop stories I read involve using some type of 3rd party props.


#3

Thanks Mike. To be fair to MA, I’ll throw in one other possibility of the crash now that I have the top off. The flight controller module was not adhered tightly to the centerboard like it should have been, and like it has been in the past after other crashes. This is the third FC I’ve installed on this AC, and when I did it fairly recently, I used the original double sided spongy tape to secure it to the board. It is possible the FC came loose in the cold weather? When I stuck the FC back on, the original tape was torn in the middle, so I had a front piece of tape and a back piece of tape holding the FC to the board. Could it be one end came loose first, and that caused the initial rough vibration of the AC, and then the second piece broke loose which made the FC completely loose and which brought the AC down? Or maybe, and it seems more likely, the FC came loose from the crash impact. The suspected broken prop has dirt embedded within the new exposed break which makes me think the break happened first, then it hit the dirt. And it’s like that on both sides of the prop (two breaks). But the other broken prop, on the front right side is clean at the break which to me implies it broke on impact. So I can’t ignore the possibility of the FC coming loose during flight, but I still like my first theory best.


#4

Okay, I’m going to throw out my original broken prop theory.

I just did a freezer test comparing a Master Airscrew prop and an OEM DJI 9450 P3 prop. I stuck the two props in the freezer for 20 minutes. Took them out. Bent the MA prop 90 degrees. It bent but wouldn’t break. Bent the OEM prop 90 degrees. It snapped instantly.

Repeated it with the MA prop a second time. 20 minutes later the prop still wouldn’t break at 90 degrees. I forced it to 135 degrees and it did finally snap.

I am pretty darned certain this problem was caused by twice re-using of the spongy tape holding the FC to the CB. The tape is barely tacky now. I believe the FC came loose in the cold - first one end, then the other. My careless mounting job is to blame, but a good lesson is learned.

Here’s the raw video. The apparent rough flight you see during the first 80 secs is a typical view from a P2V camera on the stock 1-D gimbal mount. But starting at 1:22 secs, it becomes quite a bit more rough which isn’t typical unless there are something like 20 mph sustained winds with higher gusts. Wind was only 10 mph on this flight. Something was obviously wrong. I should have immediately reset my home point and landed but instead I flew on. AC went down about a minute after the vid ends.

My apologies to Master Airscrew.