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...John, at the risk of sounding.. like.. whatever.. Fatigue or Stress Crack Nucleation typically starts at the point of Maximum Stress & Minimum Strength.. while several other users here have suggested drilling a hole to halt the crack propagation, I again don't think its a good idea, with this material, in this area of the craft.. I realize that it is a 'Technique' used, in this case I believe it to be not applicable (BTW none of the suggestion volunteers offered a Dimension of that hole haha).. filing a claim with DJi, in this case I believe will honored, but what will more than likely happen is you'll have to send your drone in to them at which point it'll be swapped out with a 'ReFurbished' drone.. again some don't mind that, I do... I've taken great care of my craft, I would say i've treated it like an infant, but i wouldn't send an infant 400' AGL haha.. and I don't ride the Firmware UpDate Tinkeristis Bandwagon.. I'm running the original firmware installed upon receipt and aside from this structural defect, problem free.. I made a tool of sorts out of copper wire so as to apply a malleable (vs Brittle) epoxy to the inside, to strengthen that area.. it worked on the left side, rather than further crack propagation there, it cracked on the right side.. good luck...
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IIIDaemon
www.GasRecovery.net