P2V+ Fell out of sky and No Fly Zone question

[TheWire]

I was flying my P2V+ V3 at about 70' I went to descend and pulled the left stick all the way down while the right stick was centered. I'm not sure of the precise timing, but it seemed to me the motors stopped very soon after the left stick hit the detent position. A gimbal damaging crash occurred.

I had recently switched the flight controller to NAZA mode. After the crash I connected to verify Intelligent Motor Cutoff was selected, it was. All 4 motors also fired up. I may have been near the edge of a NFZ. But the bird took off normally and I flew less than 200' from the home point. My understanding if I flew into a NFZ it should self land, not cut off the motors in mid air. Any thoughts on what may have happened?

I'm now in the unhappy decision making process of having the gimbal repaired, replaced or bite the bullet and go to P3. I don't think I want to even consider a new gimbal unless I can figure out what caused the bird to fall.

 

[MapMaker53]

The only way left stick down turns off the motors is if the Phantom's barometer detects no change in air pressure (as in not descending) for a few seconds. So it's my guess that your shut down could have only been due to a faulty barometer unit or a sudden loss of all power. Did you happen to notice if no lights were on as it was falling?

 

[TheWire]

Thank you Map Maker. The FPV screen had a picture froze of the ground at the impact site, so it seems power was on during the free fall. A couple weeks ago my P2V+ flipped into a couple inches of water on takeoff from a angled rock. I snagged it out quickly, but the hull still got water in it. I thoroughly dried it for days, but water may have gotten in the flight controller. I did an advanced IMU cal and other diagnostics looked good. It seemed to perform well for 10+ flights after this.

The altitude reading on the DJI vision app seemed normal during the last 10+ flights. Would the P2V+ perform OK in GPS mode flight with a bad barometer?
Does the left stick have to be in detent position for the motors to shut down after landing? This may have been the first time I pulled the stick into detent in flight since the water incident.
Because my gimbal isn't functioning, my telemetry is down. I was hoping I could see the altitude or raw barometer from the Assistant software, but I don't see a display for it. I may open up the NAZA to see if I can see any water damage.

I'm going to look into seeing if I can replace the barometer sensor. If not, with the gimbal damage and having to by a new NAZA, I don't think it pays to repair it. Wish I would have tried to fire the motors back up during the 70' free fall, but I was too entranced watching the disaster play out.

 

[MapMaker53]

I think flying after water gets into the electronics is a roll of the dice. No telling what was damaged as a result of a sudden electronic short when water hits the electronics. May often be lucky after drying it out, but maybe not.

 

[RoyVa]

Navy ships have water damage all the time. The components are dried, tested and put back into service. Many a Phantom has go into the brink and recovered except for the batteries. They are trashed if they get soaked. I would look elsewhere for the cause of the crash. Full loss of power is normally a battery or battery contact issue. Start in the assistant and see what info you can get on the battery you used. Pulling the left stick to decent won't cut of the motors unless it detects the Phantom has stopped it decent for a few seconds. All the sensors are sending data on that action to the main controller. Haven't know of any to shut off from the decent position yet without being on the ground. CSC is a different issue. That will shut her down.

 

[MapMaker53]

Well, I don't think a Navy jet would be dried out after landing in a lake and then immediately put back into the air, because major electronic components will probably be damaged from shorting out and being fried upon immersion, which is what many Phantom owners do after a water accident and was my point. The OP didn't lose full power because his wifi and camera operated during the fall and gave him a visual of the impact. So unless someone has a better idea of what caused the failure, I'll stick to my theory that it was due to damage to an electronic component as a result of water immersion. Maybe the bird brain is having an occasional stroke and thinks it is getting a errant CSC signal while in the air as a result -- because I frankly don't know what else would shut down all 4 motors in the air.

 

[robsquad]

are you using prop guards ?

Prop guards and VRS | DJI Phantom Forum

 

[TheWire]

Yes, I had removable prop guards on, which I use if there are people around. VRS is an interesting possibility. In the link you sent me it talked about multiple people having this issue. But some thought it might be minimized with the firmware changed that slowed the rate of decent. I take it with VRS the props stay running but they can't move enough air to keep the bird in the air?