C172 vs Drone

z987k

Well-Known Member
The only reason I mention the impact damage is because it looks a lot like what I saw several years ago, but you probably have the better answer there, it's quite likely I'm out to lunch. I'm a bit curious about resonance being an issue, though?

You know, I've actually never heard of resonance being an issue on light airplanes that didn't have radials, you have any links about resonance on GA airplanes? I'd love to read more, I know it's an issue on the larger 4-bladed PT6s occasionally (I'm looking at you D model 1900), but never heard it being an issue on GA airplanes.
Most props have an rpm avoid range. It's a lot worse with aluminum than composite and a lot worse on a 4 than a 6, but it's still recommended with the composite to.

Here's the graph out of the manual with my prop where they explain why they recommend avoiding continuous operation in a certain rpm band I'm sure you can deduce from the graph. They also meantion that the prop has more than 150% safety margin even at the 2300rpm stress level for unlimited operation and unlimited cycles at 2300rpm if you wish.
Screenshot from 2020-01-13 15-27-01.png


Here's a site that explains it fairly well I think - Propeller Vibration: Issues, Examples, Consequences, by EPI Inc.
 
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fholbert

Mod's - Please don't edit my posts!
Looks like this happened at El Monte CA.

I'm sure the missing prop blade has been found by now.

06-JAN-2020:09:00ZN1658FEL MONTECALIFORNIACESSNA/172ACCIDENTSUBSTANTIAL0AIRCRAFT EXPERIENCED PROPELLER MALFUNCTION IN FLIGHT, EL MONTE, CA.

Capture.PNG
 
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