Prevent stress cracks

Joined
Apr 10, 2015
Messages
2,248
Reaction score
460
Location
Virginia
Several users are reporting after getting their planes and with little use they are getting stress cracks at the end of the arm along the outside edge of the outermost screw.
I believe that the Birds are assembled in an air conditioned plant and the screw are installed to a specific torque. Once the plane arrives at its home and the temperature outside is much higher the plastic expands and thus the screws become to tight and stress the plastic.
My recomendation is to loosen the screws and re tighten when you bird is at operating (outside temperature in summer) that way they will not expand and over tighten causing stress and then the ill fated crack. Hope this helps.
 
Joined
Mar 6, 2015
Messages
69
Reaction score
12
Location
USA
Good point RoyVA. I see many pictures of stress cracks here, and some seem to eminate from the motor mount screws too. I think that, in addition to balancing your props to avoid unnecessary vibration that would contribute to the problem, one should loosen and re-seat all of the shell screws, not just the outermost phillips head.

Of course, then you must do periodic checks to ensure all screws remain snug and fully engaged. I know "snug and fully engaged" is more than a little short of torque specs and that the phrase may irritate some of the purists, but I seat mine by feel because I have no idea of the correct torque to put on these.
 

N017RW

Premium Pilot
Joined
May 2, 2014
Messages
8,961
Reaction score
3,249
Location
Palm Beach Co.- FL
Don't use ANY threadlock NOT approved for plastic.

It will out-gas and make the surrounding plastic brittle - think you have cracks now???
 
Joined
Jun 17, 2014
Messages
315
Reaction score
60
Location
North Alabama
It's also a good idea that when you are reassembling your Phantom shell that you rotate around to each screw, equally tightening each just a little until all snug (not tightening one screw all the way, then the next, etc). Same should go for dis-assembly, gradually loosening all screws until all torque is gone. As for the small phillips head screw, it should be the first you loosen and the last you fully tighten.
 
Joined
Aug 17, 2014
Messages
1,400
Reaction score
615
Location
Long Island, NY
I agree, but suggest two additional rituals when tightening or loosening the screws. (1) Work in a crossing sequence - first loosening a screw on one arm and then loosen the corresponding screw on the opposite arm - working your way around the craft similar to removing/tightening automobile wheel lug nuts. (2) Work your way from outer-most screws to inner-most screws when removing, and then inner-most to outer-most when tightening.
 
Joined
Apr 5, 2015
Messages
221
Reaction score
23
Age
62
I agree, but suggest two additional rituals when tightening or loosening the screws. (1) Work in a crossing sequence - first loosening a screw on one arm and then loosen the corresponding screw on the opposite arm - working your way around the craft similar to removing/tightening automobile wheel lug nuts. (2) Work your way from outer-most screws to inner-most screws when removing, and then inner-most to outer-most when tightening.
+1
 
Joined
May 16, 2014
Messages
3,530
Reaction score
625
Location
Sydney Australia
I use a glue gun on all 4 arms to prevent/minimise stress cracks.
 

New Threads

Forum statistics

Threads
139,306
Messages
1,437,351
Members
101,179
Latest member
UAmetry