Don't over tighten Props

Wow! That must have been tight. Sometimes it's difficult to judge how hard something has been tightened. I think some of the clue as to how hard to tighten is 'built-in' to most spanner sets. The smaller the nut, the shorter the spanner - which means less force can be applied. This goes out of the window with ratchet sets, locking pliers, or adjustable spanners, where the lever arm remains the same length, becoming progressively 'too long' for smaller and smaller nuts. People do come up with little empirical rules like - 'finger tight, and then a quarter turn more' - which works most of the time as long as there's no roughness to the threads. Bottom line, it's often just about experience - I doubt you'll repeat that mistake. Of course, one of the reasons for the need for 'excessive' tightening is the problem of counter-rotating props - normally the motion of the engine is 'tending' to tighten the nut by default, due to the way the thread runs. On counter-rotating props the opposite is true - the rotation is tending to loosen the nut. 'In theory', you only need to pay real attention to the ones that naturally want to unscrew. Thanks for sharing, I'm sure there's a few folks will be rethinking how much to tighten their props after seeing this. Cheers, alibopo.
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Hi

In your case the documenting photos show its a cause, over tightening the prop's. When I first started flying Multi's my props broke from hitting the ground at high speeds, as I got better? They started snapping off at the hub from fatigue. We ask a lot of these little bits of plastic on a multi. Side loads, Constant flexing up and down, as you apply the throttle. Where a plane just ask's a prop to pull it along.

Then I moved on to the Carbon/Nylon Props. They with stand the loads much better and rarely snap at the hub? But the trade off is they are brittle, and will crack if you hit something. They are hard to find. Been ripped off on Ebay 3 times now. Even after emailing them to make sure they were Carbon/Nylon. So now I have enough props for a life time for my planes.

I fly mostly Carbon props on all my multi's. They are more expensive. but I trust they won't break in mid roll or flip. My 2 Cent's
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Another thing to consider is that cheaper price sometimes means cheaper material. I bought some props this year and unfortunately the hubs cracked easily after I tightened the nut. I had to throw them out. It is sometimes better to invest a little more for props.
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I have the same motors and I love them. I do not have to tighten my props above finger tight because I bought ccw prop adapters so two of my motors have those on them enabling my props to self tighten just from the torque. I can give you the link if u are interested.
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Good article. There is light flashing on the props that can cause problems also. On turbines sharp edges and scratches can cause failure. I imagine on anything spinning at 10,000 to 30,000 rpm can find weak spots. Lol
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