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Mavic propeller hitting body
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1357 41 2017-8-8 03:33:02
Slic Ric
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To the point. The port side forward prop is hitting the body of quad just above the avoidance sensor. Not all the time, and just one end of the prop. I thought it was a bent prop from the crash, so I swapped it to no avail. I thought the prop was only striking during full power climb (up) on "sport" mode but no on "P" also casused a strike. Nothing seems bent. I have seen many videos of this quad taking a beating and flying away so I am disappointed that getting the blades wrapped in palm fronds has caused me such trouble. I'm just in awe of my bad luck.
My first post. I've read alot here before and after getting my Mavic. THANKS to everyone who participates for being here. I'm trying to get used to the layout of this forum however I haven't seen anything related to my issue when trying to search.
Should I try another new prop? Could I have had a bent one out of the box? I'm worried it will seem fine until I get it out of sight then it starts striking again. It makes a hell of a noise and drops when it strikes. Should I take it apart? I imagine I will have to send in to refresh. Any thoughts? Should I expect the scarred body parts to be replaced or will it just be flight components? I just wish the problem was obvious.
IMG_20170807_164643415.jpg IMG_20170807_164619044.jpg IMG_20170807_164613040.jpg
  
-Ric
"Relectantly crouched, at the starting line"





2017-8-8 03:33:02
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trica de
lvl.3
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Germany
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I had the same but not that crasy like yours - I was in sports mode and it was a bit windy...
2017-8-8 03:42:32
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Route77
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United Kingdom
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In the top pic, there is a bit of a gap between the lid of the mavic, it does not look seated right.
2017-8-8 03:53:40
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MARSAN
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You mention a crash in your post, what exactly happened?
2017-8-8 04:14:47
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neo0
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Looks like the housing is not set down completely from the looks of your photo
2017-8-8 06:00:27
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DronePix
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Route77 Posted at 2017-8-8 03:53
In the top pic, there is a bit of a gap between the lid of the mavic, it does not look seated right.

I agree.. it looks like the cover was partially popped!
2017-8-8 06:01:49
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Lucas775
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I agree with everybody else, the top lid is not all the way down.  
2017-8-8 06:22:07
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Slic Ric
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Thank you for your replies.
The "crash" was simply wrapping the props up in palm fronds. I never hit anything solid. I pulled the quad out of the mess and flew it home. I didn't see any marks on the body at that point. I replaced the port side forward prop only after the next flight when I noticed the marks on the body.
I agree the "lid" looks pulled away, however, look at the bottom pic. The prop has caused the illusion of a gap because of warping the plastic. There certainly doesn't appear to be a gap substantial enough for the prop to strike, let alone be "under" the lid.
I mean... right? I'll take a ruler to it when I get back to the office today.
2017-8-8 06:45:46
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Henry M.Y.
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I would check the integrity of the port side prop mount and the port side motor mount to verify the correct geometry. It seems to me there is a problem in either of the two.

Henry
2017-8-8 06:47:10
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bluemarley67
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i would try a different propeller and hover hit all directions let drone position itself and see what happens. as mentioned above your body looks to have come apart maybe you could re-seat it
2017-8-8 07:20:59
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DocDNA
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I had the same problem. It ended up that the motor screws had worked loose. I removed the landing strut / leg, tightened the screws, and the problem went away.

If this is the problem, it's easy to check. Try to "wiggle" the motor that has the prop strike, and compare it to the other motors. On mine, the motor causing the prop strikes was noticeably loose.
2017-8-8 07:30:06
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DJI Diana
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Could you please provide the details below if it is possible?
1. A short video about this drone when it is taking off;
2. A close-up picture of the motor on this arm;
3. A close-up picture of the joint of this arm and the drone body.
2017-8-8 21:35:12
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Bradders
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Looks like there is a gap in the mavic body ... Could the propeller be bent also ? Does DJI recommend us using these Carbon fibre blades, I can imagine they would be stronger in flight  http://amzn.to/2wGKyO0
2017-8-9 00:33:39
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dancopter
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Bradders Posted at 2017-8-9 00:33
Looks like there is a gap in the mavic body ... Could the propeller be bent also ? Does DJI recommend us using these Carbon fibre blades, I can imagine they would be stronger in flight  http://amzn.to/2wGKyO0

They're not going to fix this issue.
2017-8-9 01:27:45
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Slic Ric
lvl.2
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United States
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DJI Diana Posted at 2017-8-8 21:35
Could you please provide the details below if it is possible?
1. A short video about this drone when it is taking off;
2. A close-up picture of the motor on this arm;

Thanks again everybody for taking the time to offer your suggestions and observations. I learn from your experience.The prop that was striking is bent. I have replaced the prop and taken measurements to compare port and starboard and all looks perfectly straight. I can't seem to multi-quote.
Henry M.Y.  : Taking a steel rule on flat surface shows no deviance in geometry between both sides at body, motors, arms and prop ends (with new prop). I can't "see" an issue.
bluemarley67 : I will record a video when I get back with new props. The loose "lid" or "top" is mostly an illussion from the warped plastic. The lid has been lifted ever so slightly by the warped plastic. In my observation, the lid would need to be lifted by nearly 6mm to afford the room for the prop to strike under the lid seem. I will disassemble to verify, but look closely at the below pics.
DocDNA : thank you.  You had the same issue? I have not disassembled anything yet. I removed the prop and tried to wiggle the motor. It has no wiggle. Seems perfectly tight. The 3 screws under the prop are tight. The 3 screws under the motor at the landing leg (strut?) are tight. although one was able to be tighten 1/4 turn hand tight.
DJI Diana : Can't record a video until later today. Pictures below.


Bradders : the one end of the prop that was striking is bent. By almost 2mm. I would imagine carbon props would potentially cause more damage by not being as fexible.
dancopter : agreed. :-)

here are (probably way too) many pics
IMG_20170809_083917752.jpg IMG_20170809_073519257_TOP.jpg IMG_20170809_073541721.jpg IMG_20170809_073415984.jpg IMG_20170809_073318264.jpg IMG_20170809_073432570.jpg IMG_20170809_073406290.jpg




2017-8-9 04:59:33
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ephektz
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Slic Ric Posted at 2017-8-9 04:59
Thanks again everybody for taking the time to offer your suggestions and observations. I learn from your experience.The prop that was striking is bent. I have replaced the prop and taken measurements to compare port and starboard and all looks perfectly straight. I can't seem to multi-quote.
Henry M.Y.  : Taking a steel rule on flat surface shows no deviance in geometry between both sides at body, motors, arms and prop ends (with new prop). I can't "see" an issue.
bluemarley67 : I will record a video when I get back with new props. The loose "lid" or "top" is mostly an illussion from the warped plastic. The lid has been lifted ever so slightly by the warped plastic. In my observation, the lid would need to be lifted by nearly 6mm to afford the room for the prop to strike under the lid seem. I will disassemble to verify, but look closely at the below pics.

For my own personal curiosity, could you post a picture of the prop to body gap with the Mavic on a flat surface? Also, does that top case have any play to it, or does it feel solid?
Edit: Sorry, that was one of the first pictures you posted. Is that with the new or the old prop? It looks like there is also prop scarring on the arm. I'm assuming that is from the initial crash?
2017-8-9 05:18:13
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Henry M.Y.
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Slic Ric Posted at 2017-8-9 04:59
Thanks again everybody for taking the time to offer your suggestions and observations. I learn from your experience.The prop that was striking is bent. I have replaced the prop and taken measurements to compare port and starboard and all looks perfectly straight. I can't seem to multi-quote.
Henry M.Y.  : Taking a steel rule on flat surface shows no deviance in geometry between both sides at body, motors, arms and prop ends (with new prop). I can't "see" an issue.
bluemarley67 : I will record a video when I get back with new props. The loose "lid" or "top" is mostly an illussion from the warped plastic. The lid has been lifted ever so slightly by the warped plastic. In my observation, the lid would need to be lifted by nearly 6mm to afford the room for the prop to strike under the lid seem. I will disassemble to verify, but look closely at the below pics.

Hi Slic Ric,

Glad for me to know your Mavic Pro is in order after replacing with new prop. When I read your first post - ", so I swapped it to no avail." and the picture, I thought you were showing the situation after replacing new prop, leading me to my suspicious of the integrity of your Mavic Pro's motor mount or prop mount.

Happy flying.

Henry
2017-8-9 05:43:44
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DRONE-flies-YOU
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Are you going the distance or are you going for speeeed?
2017-8-9 06:18:16
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Bekaru Tree
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South Africa
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Hey Slic Ric - Not sure if you got sorted yet,
Looks to me as though at some time (most probably during the crash) a situation occurred where the props were still spinning but something was preventing the prop spinning in its normal track - something was forcing the port prop to spin lower in its axis at the arc close to the drone.
Looks like this in turn caused the prop to smash into the casing where it got caught - and i would guess that this extreme action has pulled the motor mounting slightly toward the drone.
Perhaps take at look at the gap between the motor housing and the plastic arm - the gap should be exactly even all the way round - compare with other 3 arms
If this gap is even minutely out then this will be the cause of the props continuing to hit the casing.
you have one pic that almost shows the gap between motor and arm - perhpas if you could take another from a little lower perspective concentrating to focus on being able to see the gap between motor housing and arm
2017-8-9 14:12:32
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Tombolian
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OK, my 2 cents... Rather than trying a new prop out of the box, I would have simply swapped it with the kitty-corner prop to see if the problem follows the prop or stays on the front port... Most likely it's the latter.  Secondly, unless I'm not understanding, if the prop is attempting to lift the bird into the air, it should be flexing upwards away from the body, not towards it... unless you have a loose motor but you've checked that already... Hmm...
2017-8-9 16:41:22
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QuanthonyTrang
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Australia
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Your motor looks bent or its not seated properly (gap looks uneven).
2017-8-9 18:29:55
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RobDownUnder
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I have not experienced this, but from an engineers view, I suspect the motor needs re-mounting or the arm is slightly damaged. The props under normal use will flex away from body. Do a test with the Mavic at idle revs, if no contact with body, do a vertical assent and decent and check again. A little white out in the strike zone will soon show if scraping occurs. The blades will possibly flex downwards under heavy braking from high speed.
Good luck at sorting this.
2017-8-9 20:49:09
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Slic Ric
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Thanks again peeps for your responses and sticking with me on this. It's been raining here so I didn't have much of a chance to get out.To clear any confusion... I flew into the fronds of a palm tree and wrapped each prop up. It held until I could get my ladder and simply "unwind" the fronds. I have never hit anything solid. After a bench inspection, and a hover in the garage, I thought everything looked good. I flew once or twice and that is when I noticed the prop's white stripe was scraped. I replaced it. A few flights later I noticed marks to the prop, the body and the sensor housing. THAT is when I stopped flying and jumped on the forum.
I wish I could multi-quote so participants get notified. Excellent responses. I hope you all stay tuned.

ephektz : pictures below. You'll see I use the rule starting at 46cm because that is the edge. With a new prop, resting the rule against the front of the fuselage (rule is 2.5mm thick) the highest prop edge to ground is 8.1-8.2cm. This matches the other side. The arm has no marks, may have been from the paint stripe maybe.
Henry M.Y. : Thanks for letting me know that I needed to be more clear in the steps I have taken to sort this.
DRONE-flies-YOU : I always go for both, but speed first :-)
Bekaru Tree : Thanks. It makes sense that the motor is out of alignment. The misalignment of axis of the spindle (rotor mast, shaft) would explain why the prop is hitting one end only. If it were simply loose it would hit both ends.... I mean... right? I did take a few pictures (above). after your comment, I placed a spark plug gap tool around, under the (what do you call it? prop coupler?) and I "see" no variation.
Tombolian : I ran out of props so I did in fact swap from the starboard/aft first. The issue follows the motor. I agree the flex from "lift" should bend the prop upward. You can see this in large heli rotor blades during takeoff or load lift. If the "lift" is pulling the end of the arm toward the body, the arm's mounting point being the axis of travel, then the blade will move closer to the body. But this would be a noticible amount of play in the mounting point of the arm I would think.
QuanthonyTrang : I don't see it. But that seems to be the top vote.
RobDownUnder : I agree. I will do a test flight a few minutes from now.

I never mean to come off in a "matter of fact" way. I'm trying to bounce my finding off of the forum and see what comes back.
This is my first quad, but I've built/flown dozens of R/C planes and stilk have my old Kyosho Nexus 30 (back when "YOU" had to control stable flight. LOL) I'm just trying to figure this out as methodically as I can with the help of all of you.

IMG_20170809_120525181.jpg
2017-8-10 04:50:06
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Slic Ric
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Well that didn't take long. Here is a 2 minute youtube video. 1:06 is the prop strike on about 70% stick lift in "P" mode. Excuse the lack of editing. I wanted to get the video up ASAP.

2017-8-10 05:21:18
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Bekaru Tree
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hey slic ric - if you have it then i think you should care refresh this problem away
This problem  causes excessive continuous wear and tear of yr mavic and affects performance and reliability and eventually probably also footage
First prize - care refresh
second prize - send it back to have arm with motor replaced and pay what they ask

if you do happen to send it back then maybe you could make a mark on each part you think should be replaced - so you can see what was replaced when you get it back.
The casing cover is obvious needing replacement.
If it was my drone i would hope the whole arm with motor would be replaced

good luck -

2017-8-10 06:48:26
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ephektz
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Slic Ric Posted at 2017-8-10 05:21
Well that didn't take long. Here is a 2 minute youtube video. 1:06 is the prop strike on about 70% stick lift in "P" mode. Excuse the lack of editing. I wanted to get the video up ASAP.
youtube video mavic prop strike

I have a theory.

The picture below is of the DJI Snail motors; obviously not what the Mavic uses but it's the same quick disconnect mechanism and easier to see.

Can you check the little nubs on the quick disconnect adapter on the motor and see if they are deeply scored or damaged? Does the spring seem weak?


2017-8-10 07:44:15
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ephektz
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Sorry, I totally didn't explain my thought process.

So, my theory is that those nubs on the motors got damaged in the crash. The mechanism is made to prevent the props from disconnecting themselves by having the locking action rotate against the direct of prop travel. If they are damaged or worn down it could provide enough movement on a hard velocity change to give the prop enough slop to impact the body of the quad. Obviously on the Mavic they are recessed down and difficult to get a look at to verify this.
2017-8-10 08:06:02
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AG0N-Gary
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If you look at the third picture from the bottom on your first group, it appears that the motor is cocked at an angle to the arm (to photographer's right).  Also, have you closely inspected the joint where that arm is hinged?  There should be NO play in it - should be snug.  There should also be no movement of the motor on the arm.  As others have said, flexing should be away from the arm during a heavy loading situation.  I think, as someone else said above, you should get it fixed properly so that something unpredictable doesn't happen in the future due to damage that could cause injury or damage to others.  Better safe than sorry.
2017-8-10 11:20:47
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DJI Thor
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Slic Ric Posted at 2017-8-10 05:21
Well that didn't take long. Here is a 2 minute youtube video. 1:06 is the prop strike on about 70% stick lift in "P" mode. Excuse the lack of editing. I wanted to get the video up ASAP.
youtube video mavic prop strike

Did the drone crash before? We recommend sending the drone in for repair.
Please fill in some info on our online repair link of our official web and then send it back, here is the link: https://repair.dji.com/en/SelfRepair/Area

2017-8-11 03:35:25
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Tealk
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i think that propeller is to soft and its bend easy ...check you propellers ...
2017-8-11 06:09:43
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Tombolian
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+1 for best thread on this forum.  This problem is trippy!!!! I can't wait for the end but I fear it will be 'replaced/problem solved' without an explanation.  Please please please prove me wrong and somebody figure this out!
2017-8-11 10:07:57
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Slic Ric
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Well I found something. I am dumbfounded at how this is happening, I hope somebody can offer some information. I'm not familiar with the composition of the foward arms (the horizontal part). Are there parts inside that make up the rigidity of the arm that could have come loose?

ephektz : Excellent theory. The Mavic prop mounts seem to be perfectly opposite of what you show in the pictures provided. As in, the "nubs" are on the props and the bayonet style "L" is on the coupler "disc". This being the case. I have replaced the prop and I have removed the coupler and checked it. No wear, warping or scarring. I did find the issue with the arm while checking your theory so thank you for that.
AG0N-Gary : I think you are mistaken. There absolutely is "some" play at the mounting (hinge) point of the arm to body. I opened the caps to check the mount point and the single screw tension. Can anybody else chime in and verify?
DJI Thor : yes, I stated that the quad had "crashed" into the fronds of a palm tree. It got wrapped up on all four props. I will be sending in for refresh.
Tealk : um... yeah. did that.
Tombolian : Maybe I found it? I ask other Mavic owners to please test your quad and compare it to my attached video below. Do you have as much movement in ANY arm as I do?

I think too much credit is given to the tolerences put into these machines. I HAVE been hearing you all. Please know that I have measured the gap around the motors (each one) and have found slight variations all the way around. I'm talking microns, but still. Had I some professional photography equipment I could show that there is no issue with the mounting point of the motor in question. If something were bent, it would be noticable in flight. In my last video, when hovering, the blades are stright across. Difficult to get a steady, dead straight shot, you'll have to trust me.
vlcsnap-2017-08-15-11h37m39s874.jpg
The props are level.
IMG_20170815_121934_715.jpg
almost perfectly opposite.

Below is the video showing the arm bending without the rigidity the opposite arm has. I focus on the connecting (hinge) point to show that the movement is NOT coming from there.


Below video shows the amount of play (very slight) in the mounting point of the forward arm.


As always, Thank you everybody for your input.
-Slic Ric

2017-8-15 08:42:29
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Nazar78
Second Officer
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Slic Ric Posted at 2017-8-15 08:42
Well I found something. I am dumbfounded at how this is happening, I hope somebody can offer some information. I'm not familiar with the composition of the foward arms (the horizontal part). Are there parts inside that make up the rigidity of the arm that could have come loose?

ephektz : Excellent theory. The Mavic prop mounts seem to be perfectly opposite of what you show in the pictures provided. As in, the "nubs" are on the props and the bayonet style "L" is on the coupler "disc". This being the case. I have replaced the prop and I have removed the coupler and checked it. No wear, warping or scarring. I did find the issue with the arm while checking your theory so thank you for that.

Both my front arms are definitely rigid. Where's this part (screenshot attached)? I assumed missing during crash? I think that's the cause.
Capture.PNG
2017-8-15 10:21:32
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Slic Ric
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Nazar78 Posted at 2017-8-15 10:21
Both my front arms are definitely rigid. Where's this part (screenshot attached)? I assumed missing during crash? I think that's the cause.
[view_image]

Thank you! That is just a cover that was recently removed to check the mount point of the arm.
2017-8-15 11:06:13
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Nazar78
Second Officer
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Singapore
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Slic Ric Posted at 2017-8-15 11:06
Thank you! That is just a cover that was recently removed to check the mount point of the arm.

Try gripping the top and bottom part of the arm housing (the missing cover area bottom and top) with your thumb and index finger, see if the arm still flexes. I believe something around this area got chipped or cracked or the screw thread loosen.
2017-8-15 11:26:27
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RobDownUnder
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Nazar78 Posted at 2017-8-15 10:21
Both my front arms are definitely rigid. Where's this part (screenshot attached)? I assumed missing during crash? I think that's the cause.
[view_image]

Just checked the arms on my Mavic. The joints are close to rigid, maybe half a mm each way from centre. Totally rigid would not swing, but yours seem very sloppy by comparison.
Send off for repair. There could be a crack or distortion to the arm mount area.
When you think about the stresses, the only way the prop can hit the body is for the arm to swing upwards tiliting the blades down onto the body. If the arm was rigid this would not happen. but the rotational upward force for lift off is rotating the arm upwards in your case. I hope fellow fliers look at this because this could be a classic sign of critical damage if left unrepaired.
2017-8-16 00:41:57
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Slic Ric
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I've been out of town for awhile (without my drone -sigh-) I am sending the Mavic in for repair and I was offered "Express Refresh" alternatively to a repair. As much as I would like to know what has happened to my Mavic. I have been without it for too long so I just went with the replacement. I will keep this thread alive until my replacement Mavic is not only in my hands, but proven to be in good working order.
2017-9-12 10:09:20
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DJI-Mark
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Canada
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I am sorry if it seems like I am jumping the gun on this. It does look like this aircraft would benefit from having a technician look at your aircraft. You can always set this up for a repair.
2017-9-12 12:40:01
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Slic Ric
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DJI-Mark Posted at 2017-9-12 12:40
I am sorry if it seems like I am jumping the gun on this. It does look like this aircraft would benefit from having a technician look at your aircraft. You can always set this up for a repair.

I was struggling with whether to send it off for repair or Express replacement. I have SO little flight hours, and (other than the one time) no accidents and it has been very well cared for.
2017-9-13 11:17:40
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DJI-Mark
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Slic Ric Posted at 2017-9-13 11:17
I was struggling with whether to send it off for repair or Express replacement. I have SO little flight hours, and (other than the one time) no accidents and it has been very well cared for.

I understand the concern. The problem is that this could be the tip of the iceberg and there may be more wrong. Just my humble opinion.
2017-9-13 11:23:47
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