Stress Crap

[Stevedots]

Hello All,

I know the stress cracks in the Phantom 3 Advanced aren’t a new topic but I think I’m the first to have this happen.

After discovering stress cracks both on the bottom and top shells I opened her up and I was shocked to see what I found! Not only multiple micro cracks but two of the ‘metal’ bases that the eight inner screws attach to came completely separated from the top shell!

This is beyond stress cracks; this is “Stress Crap”! Every one of the eight metallic screw bases has multiple micro cracks surrounding them. And as I said two of them completely separated from the top shell. Fortunately I have them both and some micro pieces of plastic to do a home repair.

No way is this going back to DJI in spite of their reputation for “excellent customer service” (sarcasm)! But from what I have read here it seems that all their replacement shells have the same flaw and most likely will eventually crack as well.

I wanted to thank everyone here for repair recommendations already posted. With that information I plan on a three pronged approach to the stress crack problem.

For all the “micro” cracks I’m going with the Weld On 4, with its needle like applicator and water like consistency it should sink into the micro cracks and seal them up. My second repair/prevention will be an application of Plast Aid to strength all the area’s that I can safely coat without messing up the motor mounts. And lastly my third treatment will be a coating of “Light” Hangar 9 fiberglass cloth on the outside of the top and bottom arms. I am going to extend the cloth covering up the vent areas.

(check update below don't use Eze-Kote!)

I may use a two part epoxy for the cloth but I have a resin based, water soluble produced called Eze-Kote that I would like to mention. I think it will be lighter than epoxy but I have to test and see how it bonds to this “f-upped” plastic. Eze-Kote is made by Deluxe Materials. It is really made to cover foam and balsa planes but I have used it on large r/c boats too. Once it is dry it is water and fuel proof, it also dries in 20 minutes, can be sanded and take paint.

I have no vested interest and do not make any money from this product. I only post a link so people can check it out. This is a UK web site but you can get this in the USA:

Eze Kote - Deluxe Materials

My P3A was purchased January of 2016…no bad crashes…no bad landings…just bad plastic!

Steve

 

[Numone]

Sorry to hear about your issues. Just as a side note, I don't think Weld On 4 will bond to the shell, as its made from styrene; Weld On 4 is for bonding acrylic and polycarbonate, so you could end up with a real mess.

 

[Stevedots]

Thanks Numone,

I will look for an alternative for the micro cracks, figures I already ordered some and it should be here tomorrow or Monday. Oh well I suppose I will find a hobby related use for it eventually.

 

[Stevedots]

Hi Pilots,

Update:

Forget the Ez-Kote, I guess its only best for balsa and foam, I tried it on a test piece and I was able to pull the cloth right off the test piece! So I may just use a two part 30 minute epoxy, maybe thinned just a little bit with denatured alcohol.

Since the Weld On 4 is for the wrong plastic I did some searching for a good bonding agent for styrene. I found this information on a model RR web site where these guys work with a lot of styrene, and I quote from that web page:

"I use regular MEK (Methyl Ethyl Ketone) from the hardware store. You can get a 10 year supply (1 quart) for less than $10. You can also get it from Testors in the black bottle with a needle applicator, but they'll charge you $7 for a tiny supply. It's essentially MEK, with a few other additives that make it slower. Personally, I prefer straight MEK -- it sets up faster and you can find it pretty cheap in hardware stores."

So I'm going with MEK, methyl ethyl ketone. In very small amounts it should 'fuse' the styrene cracks together. I did go to the local Hobby Shop for micro brush applicators to apply the MEK.

I'll post some photos after my repair work and let you pilots know how the MEK and epoxy/cloth works out.


Steve

 

[BigAl07]

I've used the adhesive that is "Blue Light/UV Activated" and it works GREAT! Has been rock solid on several cracks now for over a year. It's sometimes called "5 Second Fix"

 

[Stevedots]

My attempted repairs did not go well.


I may, after I calm down order a new upper and lower shell but they way I feel right now I’m in no hurry to get involved with any DJI products.


Bad plastic, (or bad structural design), constant manipulative firmware updates, bad customer support. It is almost like they want to lose customers.


Well, they have just about lost this one!


Thanks just the same for the help. The best thing about DJI is its customers in this forum and their willingness to help each other.


Steve

 

[Stevedots]

I've calmed down, after a couple of shots, and ordered a replacement shell.

Not only did I screw up the repair but I kept finding more cracks so in the long run I'm better off starting with a new intact shell.

But I am not looking forward to a total disassembly and reassembly.

Keep flying!

Steve

 

[BigAl07]

I've calmed down, after a couple of shots, and ordered a replacement shell.

Not only did I screw up the repair but I kept finding more cracks so in the long run I'm better off starting with a new intact shell.

But I am not looking forward to a total disassembly and reassembly.

Keep flying!

Steve

Last time I went into my P3 shell I had a couple of screw bases that were broken so I went around the whole hull and reinforced each one every so slightly.

 

[Stevedots]

What a difference a good night’s sleep makes. I woke up in a much better mood and ready to disassemble my P3A. With the help of iFixDrones video I now have it completely apart. Hindsight being 20/20 and with that video it wasn’t as bad as I was anticipating. The only part I haven’t removed yet is the GPS module from the top shell. I want to keep that together just so the sticky foam cover/shielding doesn’t pick up dirt and dust while waiting for the new shell.

BigA107, you are right. I found more cracks around just about every screw mount that has the threaded metal inserts. I am glad now that I went with a completely new shell. I will follow your example and carefully strengthen the new shell before reassembly.

Sorry for ranting, I may have had a lot of bad things to say yesterday about DJI but I do have respect for their electronics. The inside of the P3A is a lot more impressive than its outer shell.

Thanks again for the support,

Steve

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[Numone]

View attachment 88227

What a difference a good night’s sleep makes. I woke up in a much better mood and ready to disassemble my P3A. With the help of iFixDrones video I now have it completely apart. Hindsight being 20/20 and with that video it wasn’t as bad as I was anticipating. The only part I haven’t removed yet is the GPS module from the top shell. I want to keep that together just so the sticky foam cover/shielding doesn’t pick up dirt and dust while waiting for the new shell.

BigA107, you are right. I found more cracks around just about every screw mount that has the threaded metal inserts. I am glad now that I went with a completely new shell. I will follow your example and carefully strengthen the new shell before reassembly.

Sorry for ranting, I may have had a lot of bad things to say yesterday about DJI but I do have respect for their electronics. The inside of the P3A is a lot more impressive than its outer shell.

Thanks again for the support,

Steve

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Well done Steve - I really think that was the best decision.
In reality, DJI have sold millions of P3 drones world wide and, like mine, the vast majority of these are crack-free. However, I think I was lucky from the off. I initially fitted prop guards and when I removed the screws (or bolts to be accurate) to be unbelievably tight which, given they have thread lock, was completely unnecessary. I cleaned-off the original threadlock and replaced it with Loctite 425, replaced the screws and tightened them to just beyond finger tight; I did the same after I removed the guards after my first ever flight.

 

[Stevedots]

Thanks Numone,


Here is the new shell, and the addition of some Callie Graphics I had lying around for an F-16 project. I did add two part epoxy with micro-balloons around every screw hole and possible weak spot inside the upper and lower shells also lock tight on every screw that was ‘metal to metal’.


Here are some photos of the newly renovated P3A already test flown and back to 100% operation!


Steve

 

[macoman]

You guys have balls... I will never able to do something like that... Taking apart the whole phantom. That's crazy.

 

[Stevedots]

Hey Macoman,

Thanks but until I found that YouTube video (6 parts to it!) I wasn't looking forward to doing it at all. After doing it it wasn't as bad as I thought but I'd still be using that video as a guide if I ever needed to do it again. I'm hoping that with the epoxy reinforcements that I never have to do it again!!

 

[Numone]

You guys have balls... I will never able to do something like that... Taking apart the whole phantom. That's crazy.

Yeah you would, if you didn't want to waste your money!

 

[RJay]

Thanks for the nice video... Actually... I have replace my p3 shell 3 times already... its not very difficult... you have to take care when tightening the screws... Just enough force to tighten them...

 

[Stevedots]

Update:


I took the P3A out for a second test flight today. Went to the Mystic Lakes in Medford/Winchester area to do some photography and video. There happen to be some sailboat racing so that was a great subject. The Phantom worked perfectly after the shell change. The photos and videos came out very nice, so I didn't screw anything up with the electronics doing the shell change.....or so I thought!!

I came home and unfortunately I found 2 cracks, that was after 4 flights in breezy conditions and with perfect manual take offs and landings. These are very fine 'hairline' cracks in the left rear and left front arms between the motor mount screws. I was careful not to over tighten any of the screws but I did use a very tiny amount of lock tight on all the screws that screwed into metal, no lock tight was used on any of the screws that attach to plastic.

Well, even though I used a really tiny amount, and I mean tiny amount, some of it must have pushed its way out of the threaded metal screw bases on the motors and migrated into the plastic because one of my cracks has a blue color to it and I used blue lock tight! So I can't blame DIJ for the cracks in the brand new shell this time.....unless I start to get cracks in areas where no lock tight was used!

At this point the cracks are so fine that they can't even be clearly photographed. Since I did put epoxy in the inside of the top and bottom shells I don't think I really have anything structural to worry about but I am going to coat the outside of the bottom of the arms with some cloth and epoxy, just around the motor mount screw areas.

I have learned another lesson, if I do change the shell in the future I WILL NOT use any lock tight. Maybe a drop of CA instead, I know that won’t cause any cracks!

Here are a four of raw photos from today.


Steve

 

[pomonabill220]

WOW I am concerned now after reading your post.
I have a P3A as well and even though I have had it for over a year, it only has about 10 MINUTES air time... yep that's right 10 minutes!
Before I go up again, I am going to pop the top and take a look at the metal inserts.
The inserts are supposed to be press fit, and because the plastic that is used (crappy), the pressure of the press fit must have split the plastic.
The bosses probably have too thin walls, and brittle plastic that makes them split or crumble... I am no expert on plastic, but I have seen this on other things and am making an assumption based on experience.
I have also read that locktite will crystallize plastic, and not to use it on these weak shells... I would like to hear if locktite can be used, and which one.

Sorry to hear of your "plight", but glad you posted! Good luck.