Possible answer to why some have cracked shells

My oldest P3P has almost 300 flights without a single issue. All others are perfectly fine too. No cracks, no flyways, no crazy batteries, just smooth and reliable flying - and the occasional rough landing of course, but that´s my fault.

I doubt that accelerations or even unbalanced props cause cracks in "good" shells, as opposed to "bad" ones with some problem in the plastic mix or cure (as I believe) wich may crack regardless of extra care. There´s no indication whatsoever as to the percentage of good Vs. bad shells, but I´d guess most are OK and won´t crack.

Still, it´s always a good idea to have props balanced anyway. DJI original props are 90% fine most of the time, but some may require a touch. I´ve never used third-party props, only DJI´s and most come almost perfect from factory.
 
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I would like to know the critical speeds of the motors and how close they are to idle and hover speeds.

Motor harmonics, flight attitudes, plastic compound/cure and prop balance are about it for reasons unless screw torque contributes.
 
Dacon hit the nail on the head. (IMHO)

The first thing I did when my P3P arrived: Re-Torque every screw.

Some were very very tight. Way too tight for plastic IMHO.

No issues so far.

Bit
 
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How many of you, with cracks in the shell, have balanced your props?
Man, are the cracks inevitable or are there some people who have had no problems? This just gives me anxiety!
I have 67 flight on my advanced and I have no cracks to date, but the anxiety eats a guy up. I check pretty much every flight expecting the worst!
Most P3 never developed any cracks.
There must be a dozen proposed causes or remedies and most are not backed up by any evidence.
If it was as simple as temperature or vibration or adjusting braking or reinforcing plates, screws tight etc, the majority would have developed cracking.
But it's only a small fraction that did.
The only explanation that fits the evidence is that there was a problem with materials and/or moulding technique for one/some batches of production.
If you were unlucky enough to get one from that batch, you could develop cracking.
If (like most owners) you got a good one, you won't get cracking.
 
Most P3 never developed any cracks.
There must be a dozen proposed causes or remedies and most are not backed up by any evidence.
If it was as simple as temperature or vibration or adjusting braking or reinforcing plates, screws tight etc, the majority would have developed cracking.
But it's only a small fraction that did.
The only explanation that fits the evidence is that there was a problem with materials and/or moulding technique for one/some batches of production.
If you were unlucky enough to get one from that batch, you could develop cracking.
If (like most owners) you got a good one, you won't get cracking.
Mine is in the shop just now getting its 3rd shell. I have asked them to make sure that I get the latest shell from DJI. If this is true what your saying surly I cant get 3 shells in a row that crack.
 
133 flights, 1,473,273ft and over 22hrs, no cracks to date. Bought it back in Mary 2016 when the P3 was first released.

Is this a new month you have invented? Or do you have a time machine ;);)
 
No just over tight from DJI. Relax the screws a few turns and tighten back just finger tight.
 
It took 199 flights before the cracks around the motor mounting screws showed up. I could not have been more gentle in all operations,(always hand caught). Just got it back from DJI. They just replaced the bottom portion with the first generation crappy shell. It will be off warranty by the time it cracks again.
Now I have to decide if UAV bits are the answer or should I open it up and apply Bondex or Plasti Aid.
 
On my first shell, upper part, I had cracks on all arms. When I replaced the top shell, 3 out of the 16 motor screws and 2 out of the 8 shell screws were so tight that took a lot of power to turn them off and there was no locktite.
In case you didn't know, the same guys from DJI work on the Phantom for 4 hours and then turn around and work the next 4 hours on Yugo engine cars using the same tools.
 
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Mine too no stress cracks after 30 hours of flights. Never messed with the screws. I decided not to install any prop-guards because of that unless I get a new bird and use one for flight skills.
 
I have had 2 shells crack that was the first body type.i used bondic in the motor pods to reinforce it did help.also I am using the strong arms for added strength.no cracking in the motor pod mounts but I did develop a crack in the arm about 1cm from motor.apon further inspection I have noticed that that arm cracked becoz #3 motor is not turning as freely as the others.also when I did get my p3 back with new shell I flew it in 15/20 mph wind hard fling and developed cracks that was the first run of p3 the new shell seems fine so far!!
 
Over 50 flights and no cracks.
I bought prop guards when I first started flying, only used them twice but left the snap-on brackets on.
Might be helping but not sure
I too have the snap-on prop guards. I don't always use them, but I left the mounts on the P3P. Knocking on Wood as I type this...So far so good, NO CRACKS! Also, I don't stop on a dime or do any quick maneuvers during fight. I have 61 flights with a total of 14 miles and 6 hours of flight time. Here is my overview from Healthy Drones...
Screen Shot 2016-03-26 at 12.01.33 PM.png
 
My Standard was driven hard with no issues for the first few flights. Reading here about the cracking issues, I settled down on the hard braking and turns. I inspected the bird religiously after each outing and thought I was immune to the issue. However, when I hit the 20 hour flight time mark, I noticed (to my horror), small cracks under the motor were developing on the silver prop arms. One small crack also on the screw hole joining the two shell halves as well.

I backed off the screws. The silver mounts were particularly tight, crazy tight. I also supported the interior mount areas and screw areas with Bondic, on all arms. After the repair, I flew for two more hours. Gentle. More cracks are starting - at least one. This time on the same arm at the other screw holding the shells together. Did I just move the stress to another part of the frame?

I have the Strong Arms on order along with a prop balancer. I used the same set of props from the start but maybe there is some vibration set up and taking a toll on the frame. No crashes or hard landings, ever. Even after all the preventative action in place, I can't help but thinking a new shell is the next step.
Stats are now at 23.5 hours, 283 miles, 137 flights. Only mod is the DBS antenna on the controller (and I'm very satisfied BTW.)

My theory is 1) Mounting screws are too tight and result in damaging the integrity of the plastic. 2) Other factors including prop balance and flight stresses further weaken the shell. Perhaps microscopic cracks created by the over tightened screws develop further. 3) A certain fraction of the shells may not be made to the standard DJI requested and QC isn't catching the bad batches. Who knows for sure what factors combine for a failure to happen. I sure don't. I'm not an engineer or pretend to be. All I know for sure is that the issue is a real one and it's not from abuse. Perhaps Meta4 has said it best....

I hope more of you can post your repair results and share theories.

Update: My StrongArm supports came in yesterday and were promptly installed. Two flights and no additional cracking and the previously repaired cracks held firm. I did order the extra frame as well (2 to 4 week back order).
 
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