Update: (It Fell Today!!!)ALMOST Sudden Death Drop w/ Video

[shartlza]

So yesterday evening I was flying like I normally do and I almost lost her. I was flying about 900-1000ft out, so it was a speck in the sky. I have no FPV, so it was all line of sight. I am pretty comfortable flying these distances since I do it all the time in this area around my house. This was about 12 minutes into the flight and as i was doing a wide turn I all of a sudden saw it drop and it went behind a tree line so I thought it went down and it was about 300ft up, so I knew it was probably toast. As soon as I saw it drop as a last ditch effort I flipped the switch to fail safe as I felt my heart in my throat. As I was on my knees looking down in shame and sadness I heard something way above me and I looked up and low and behold it had come home. See the video below of the whole thing. I have no clue what happened. Scared sh*tless now to fly far out, but at least she is safe and lives to fly another day.

Any one have any idea what happened???

[youtube]https://www.youtube.com/watch?v=H5jNPHWTV1Q[/youtube]

 

[Seandyt]

Re: ALMOST Sudden Death Drop

dirty contact battery i say...check it

 

[shartlza]

Re: ALMOST Sudden Death Drop

dirty contact battery i say...check it

Are you talking about the contact pads that send the info to the naza or the actual battery terminal contacts?

 

[ianwood]

Re: ALMOST Sudden Death Drop w/ Video

Any firmware from 1.08 onwards shouldn't shut down if the battery signal pins didn't work. This is likely bad contact of the main power pins, i.e. bad solder joint, broken bracket, bad seating of the battery, etc. Or it could be a bad battery that simply gave out.

 

[shartlza]

Re: ALMOST Sudden Death Drop w/ Video

Any firmware from 1.08 onwards shouldn't shut down if the battery signal pins didn't work. This is likely bad contact of the main power pins, i.e. bad solder joint, broken bracket, bad seating of the battery, etc. Or it could be a bad battery that simply gave out.

Well I don't think it is the battery since I have had no issues with it and it only has about 25 charges. I checked to make sure the battery was seated well and it was, so it looks like it is time to open her up to make sure all solder joints look good.

 

[shartlza]

Re: ALMOST Sudden Death Drop w/ Video

Well I opened her up and all the connections and soldering joints look perfect, so nothing out of the ordinary. So I just cleaned off the battery contact prongs with some rubbing alcohol and they were a little dirty, nothing extreme though. Took it out, did a compass calibration and it flew with no issues. I am going to fly it close by for the next few flights just to make sure.

 

[Fyod]

Re: ALMOST Sudden Death Drop w/ Video

Sounds like a high gust to me.
As you're tuning, the sound of the wind picks up a bit and there could've been slight VRS.
Just guessing though.

 

[shartlza]

Re: ALMOST Sudden Death Drop w/ Video

Sounds like a high gust to me.
As you're tuning, the sound of the wind picks up a bit and there could've been slight VRS.
Just guessing though.

I was actually thinking this as well. I did notice the wind picked up as I turned. My other thought was a SW gust came over the large foothill on the other side of the freeway (which the wind does come from that direction in the evening) and it hit the craft from above on the top left side and it pushed that side down and caused it to loose control. I am just glad it leveled out and fully recovered!!! Also while i opened it up to make sure everything looked intact i decided she needed a change.

 

[shartlza]

Update: (It Fell Today!!!) ALMOST Sudden Death Drop w/ Video

Ok, so it happened again today in the same exact manner, but if fell this time. I was doing a wide ride right turn and this time the back CCW motor (back right, facing the front) threw a prop and the thing when tumbling to the ground. It was about 100ft in the air and a large tree broke its fall. Everything seems to be okay, but something is wrong.

After inspecting I did notice that the front CCW motor has a light rocky/grinding noise when it turns like the bearing are going out. Could that front CCW motor cause issues with the rear CCW motor throwing a prop. The motor that threw the prop was on the outside of the turn. I never found the prop, so I could not inspect that. I don't know if I will be fine just replacing all the motors or if it could be the ESC for the rear CCW motor. I need some advice, PLEASE HELP!!!

 

[ianwood]

Re: ALMOST Sudden Death Drop w/ Video

Could be wind. I was also thinking bird attack. But from the sound, it would appear the motors slowed down significantly or at least you can't hear them for about a second and then you could hear them again. Not sure what would cause that.

Just saw your update: Does the motor turn as easily as the others? How much play is the motor? Post up the video from the 2nd event.

 

[shartlza]

Re: ALMOST Sudden Death Drop w/ Video

Could be wind. I was also thinking bird attack. But from the sound, it would appear the motors slowed down significantly or at least you can't hear them for about a second and then you could hear them again. Not sure what would cause that.

Just saw your update: Does the motor turn as easily as the others? How much play is the motor? Post up the video from the 2nd event.

The motor that threw the prop seems fine and turns the same as the others. The front CCW motor that has some grinding/marbles hitting together noise, but turns fine and it does have some slight play. Also with the motors running you can defiantly hear some almost nocking noise like marbles hitting together in the front motor. Could the front cause the rear motor to under compensate and cause the momentum of the prop to be greater than the motor and it threw it or does it sound like the rear CCW motor's ESC is cutting out?? I will try to post video later tonight or early tomorrow.

 

[shartlza]

Re: Update: (It Fell Today!!!)ALMOST Sudden Death Drop w/ Vi

Ok here is the video. After watching it a few more time it completely sounds like the motors cut out and this could be the reason the rear prop was thrown or am I wrong. Also this was with a different battery than the other flight. The power was still on when I got to it on the ground. How could the motors just stop?!?!?!?! On another note it could not have fallen in a better place with the tree breaking its fall and it did not hit any homes, any person, or any cars.

[youtube]https://www.youtube.com/watch?v=5aizrtz1c7Q[/youtube]

 

[q8f1]

Re: Update: (It Fell Today!!!)ALMOST Sudden Death Drop w/ Vi

WOW, hope you find the problem, it's pretty worrying this things are happening.

 

[HarryT]

Re: Update: (It Fell Today!!!)ALMOST Sudden Death Drop w/ Vi

How could the motors just stop?!?!?!?!

An interruption to the power supply is the obvious answer to that question - I can really think of nothing else that could cause all four motors to stop. That would suggest something like an intermittent contact on the battery pins, a battery not seated properly, or a faulty solder join somewhere in the power train.

 

[tarro]

Re: Update: (It Fell Today!!!)ALMOST Sudden Death Drop w/ Vi

Maybe it's the Central Circuit Board, is the only thing that controls all the ESC.

 

[shartlza]

Re: Update: (It Fell Today!!!)ALMOST Sudden Death Drop w/ Vi

Maybe it's the Central Circuit Board, is the only thing that controls all the ESC.

This is very likely because when I had it open all the soldering points looked clean and perfect. That and I don't think it is a bad seated battery or bad power connection because the craft never looses power, just the motors turn off. I wonder if DJI would warrenty it since I have only had it for 6 months.

 

[Buckaye]

Re: Update: (It Fell Today!!!)ALMOST Sudden Death Drop w/ Vi

How could the motors just stop?!?!?!?!

An interruption to the power supply is the obvious answer to that question - I can really think of nothing else that could cause all four motors to stop. That would suggest something like an intermittent contact on the battery pins, a battery not seated properly, or a faulty solder join somewhere in the power train.

+1 I have seen this plenty of times in the RC heli world and it is almost always a cracked solder joint (or cold joint)

Question - do you have more than one battery? and do you know if it happened on the same one or a different one?

Wish you luck figuring it out... how much damage was there?

 

[Buckaye]

Re: Update: (It Fell Today!!!)ALMOST Sudden Death Drop w/ Vi

one thing... and it may be nothing... but if you look at the very first frame of the landing gear (right after the failure) - is that red on the leg from the sun or from the Phantom's LED? If it's the Phantom's LED then the power issue was certainly a very very short one (guessing that's all it would take to stop the motors) - but it also makes me wonder if it's something in the power line between the board and the motors (rather than between the battery and the board.

Had you ever crashed or hard landed before this?

 

[UAVDD]

Re: Update: (It Fell Today!!!)ALMOST Sudden Death Drop w/ Vi

I've never had this type of issue before until I crashed it into a creek where it stayed for about 2 minutes before I rescued it. I simply ordered new ESC boards and replaced them. Took about 2 hours to replace all 4. Solder joints could definitely be an issue. After watching it hit that tree branch the main control board that is actually the power distribution board could have a short circuit or a crack in the board itself. This is one of those issues where a fine toothed comb search is in order. Use an oscilloscope or a multimeter and test each of your leads from the main board. Check the one's from the Engines as well. Remove top shell and propellers prior to doing any of this. Switch the controller on and turn on the engines then test for power from the ESC's to the Motors. Give the center a nice wiggle while the engines are running. Try to recreate the scenario in your workshop. This is the only solution I can really offer to you from a viewers stand point.

 

[shartlza]

Re: Update: (It Fell Today!!!)ALMOST Sudden Death Drop w/ Vi

Just to note the second mishap was on a different battery, so it is not the battery. Since there was no damage to anything after the crash (how i don't know), just a missing prop, I took of the gimbal after making sure it was okay. Then i took off the props and spun it up and simulated the same control movement i was doing in the air to see if it did anything and it didn't. Then with the motors going i picked it up and shook the the f**ker all over the place to see if anything would happen and once again nothing. I guess i will take it out and fly it low (with no gimbal) and simulate the same movement to see if it does it, but I have a feeling it really need to be in the air where there is more wind and resistance. I will also open it up one more time and go through it would a fine toothed comb. I have also contact B&H, were i bought it in Feb, and they are sending my issues to DJI to see if i can get a warranty exchange. Even though the guy and B&H was trying to prove that it was not a manufacturing warranty issue. He was coming up with everything in the book like it was a IMU thing, or only one motor was going out, compass issues, and the battery contacts were loose. I checked everything after the first mishap and everything looked and felt ok.

My thoughts:
1. Not the battery since this happend on 2 seperate batteries.
2. Don't think it is a motor or motors because what are the chances all 4 would fail at once.
3. I don't think it is a main power thing because the craft does not loose. As you can see in both videos you can see the red LEDs still on. Also if it completely lost power and came back on I would think the ESCs would play the ESC start up sound.
4. There is something wrong between the main circuit board to the ESCs that is shutting off the ESCs or telling the ESCs to shut off the motors.