ENGINE DIAGNOSIS, What's your guess?

[Tiger Tim]

So I'm clearly missing something... What does this O-ring do, exactly? Does it help hold down the hub end of the de-icing boot or just keep the wire under control?

Speaking of stuff inside the spinner being easy to miss, I teach in Zlin 242s and you'd be surprised to find out how many students don't acknowledge that there's anything inside the spinner. They know they're flying behind a constant speed prop, they get the theory behind it all, they can tell you anything you want to know about the blades but somehow the hub is out of sight and out of mind.

-Tim

[Bill Greenwood]

Tim, you got close to the answer, as did B-29 and Gary.

You are correct in that the inner rubber part near the hub is just part of the boot and sort of holds down the inner end. I am calling it an O ring, I guess that you could call it a skiiny hockey puck with a hole in the center or a skinny donut. It is perhaps 3/8 inch thick.

[Matt Gunsch]

Bill,
I had a customer with a 206 that had a constant vibration than no one could find. I was doing a oil change and while turning the prop, I noticed one of the blades had more twisting moment than the others, I removed the prop and had the prop shop check the links and re-shim the blades. I got a call after the next flight saying that the vibration was gone.
As part of every inspection and pre flight, I always check the blade shake and movement by placing my thumb from the spinner opening to the blade and with the other hand, pull and push the tip fore and aft, all blades should have equal shake.
Then place the tip of the blade between the palm of your hands and attempt to twist the blades, again, all should be equal, if not, you might have worn links.

something to think about on your deicing boots, they are glued on with 1300L, weatherstrip adhesive, aka gorilla snot. I never can get it to hold weather strip, but it does hold boots on very well.

[agent86]

I know the answer! Somethings wrong!

[Jack Frost]

Years ago in the DC-3 era of airline operations, we had a crew who noticed a new vibration on one of the engines that hadn't been there when they flew the aircraft in. The crew flew it through 6 stops, the last one being our maintenence base. All the usual engine checks were run with no problem found. The prop on that engine had been changed a week or two before so it looked fine. But one of the mechs got out his tape measure and discovered one blade about an inch shorter than the others. It looked normal. After grilling the FBO who had the airplane overnight, a confession came out that the night A & P had run into the blade tip with a tug and bent it. To keep from getting caught and since he was all alone, he got out his hacksaw and cut off the damaged part, did an immaculate job of dressing out with a file and emery cloth, repainted the tip yellow and figured he was home free. Of course there was no logbook entry. If the guy had found time enough to do the other 2 blades, probably no one would have noticed until overhaul time came around. There was provisions in the maint. manual allowing this procedure (on all three blades) in case of minor damage and the guy obviously had skills to do it. He just needed supervision and honesty on the job!

[agent86]

Now that I think about it you better check and see if the"Jesus nut" is tight. Planes have a "Jesus nut' dont they? I know that on a helicopter that when the "Jesus nut" falls off , the rotor follows and all occupants meet "Jesus". If you're not ready to meet Jesus,check the nut