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  #1  
Old 12-17-2013, 11:15 AM
Toobuilder's Avatar
Toobuilder Toobuilder is offline
 
Join Date: Jul 2009
Location: Mojave
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Exclamation Hartzell with a Loose Blade

Just a heads up for those with a Hartzel C/S:

I was just out in the hangar talking on the phone and since I was standing next to the -8 I just idly grabbed the propeller tip and gave it a shake. To my horror, it moved? A bunch! Fore and aft about ? inch; lead/lag about ? inch. Moved around like the shift knob in a VW bus.

Called the prop shop and yep, this happens sometimes. We have not opened the prop yet, but it?s likely a bolt that sets the preload on the shim pack simply broke. It?s a simple fix, but expensive to open the prop.

I bring this to your attention because it goes from ?good? to ?bad? instantly. Just in case you were wondering, this is not an old, junk prop. It?s a Blended Airfoil unit with less than 350 hours on it.

I?ll get back with a full report once it?s fixed, but wanted to give you all the ?heads up? to check this EVERY flight. This was a new one on me.
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  #2  
Old 12-17-2013, 11:45 AM
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Default Wow

Michael, I sure am glad you found it, and how fortunate you found it without actually looking for a problem.
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  #3  
Old 12-17-2013, 12:13 PM
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Geico266 Geico266 is offline
 
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Keep us posted!
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  #4  
Old 12-17-2013, 12:38 PM
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Its likely the stud that sets the bearing prelload came loose. There is a locknut that holds it in place. The whole prop needs to be disassembled to do this, one blade at a time since you have to go thru the open end of the hub to set the preload on the opposite blade.

Unnerving I agree but due to inertia it probably would be fine in flight.
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  #5  
Old 12-17-2013, 12:52 PM
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Knowing the design of the propeller, I agree that the blade would be retained in the hub in all but the worst circumstances, but the issue with this is more insidious. I could easily imagine the roller bearing in the counterbore getting beaten to death and causing all kinds of (expensive) secondary damage to the hub or blade. Especially troubling is the lead/lag during the firing event.

I just hope I caught it early enough to get off lightly.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
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RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C
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  #6  
Old 12-17-2013, 03:01 PM
Paul K Paul K is offline
 
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I always grab and shake my blades before every flight. I don't know why I do this or when I started doing it but now I have a very good reason for it.

Take some photos of the inside and what ever the issue ends up being. Would love to see.

Good catch and thanks.
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  #7  
Old 12-17-2013, 04:25 PM
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Quote:
Originally Posted by Paul K View Post
I always grab and shake my blades before every flight. I don't know why I do this,,,,
Must be part of your pre-flight procedures. Good job. Way too many people who own their own planes get lackadaisical during their pre-flight inspection or worse yet,,,don't even bother at all!
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  #8  
Old 12-17-2013, 04:38 PM
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Cleaning/wiping down the entire aircraft, including the prop, after every flight is a great opportunity to spot these issues.
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  #9  
Old 12-17-2013, 04:47 PM
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As a side note, I was taught that you never push or pull a plane by the prop, if it is a constant speed.
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  #10  
Old 12-17-2013, 05:48 PM
Paul K Paul K is offline
 
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Walt, Yes, I do wipe the bugs off in the summer including the prop. It seems to really collect bugs. I don't do it so much in the winter because there are no bugs and it is too cold to wipe with my detailing spray.

David, yes, it is part of my preflight. I just don't know when I started doing this.

As a side note, this caused me to go look at my prop log with the documentation from WW. Whirlwind has some movement allowances but not very much and so far, I haven't felt any movement in the blades. About 75 hrs.
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Last edited by Paul K : 12-17-2013 at 05:51 PM.
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