A question about a prop

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clarkmueller

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Clark
I ran across a photo of a prop repair that was interesting to me. This was long enough ago that I don't even remember where I took it. I know nothing about the airplane, its owner, or why it was repaired, but the area that's been filled appears to be a good ~5mm directly into the leading edge. Even with the repair, it seems like it would be a big opportunity for fatigue. Is there anyone that can tell me more about what kind of material and technique is used here?
 

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clarkmueller said:
I ran across a photo of a prop repair that was interesting to me. This was long enough ago that I don't even remember where I took it. I know nothing about the airplane, its owner, or why it was repaired, but the area that's been filled appears to be a good ~5mm directly into the leading edge. Even with the repair, it seems like it would be a big opportunity for fatigue. Is there anyone that can tell me more about what kind of material and technique is used here?
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Looks to me like a junk prop and someone trying to hide damage. Technique? Shady people do shady things.
 
I am an IA and based just on the picture the prop is beyond limits for a repair at the A&P/IA level. This prop should be sent to a part 145 propeller repair station who can perform the proper inspection and measurements to determine out of limits. McClauly website provides some guidance on this that you can download. From my experience and data used to inspect this type of damage, the proper will surely be condemned at the repair station.
 
Bondo special,needs more paint.
 
Totally junk. Some folks just don't understand the forces on a prop and what a deep nick like that does to the strength. The lines of force pile up at the bottom of that damage and it cracks. Think about tearing a telephone book: difficult, but if you gouge a little out of the edge it will rip easily. If a prop loses a foot of blade, the imbalance can tear the engine off the airplane, and what happens to the C of G then?? It won't even glide.
 
Absolutely it is junk!!!

It is conceivable if the nick was blended out per the manufacturers spec that it would again pass, but any subsequent operation after the nick was in place would damage the parent material under the nick such that future crack propagation would still be rapid. Props (at least McCauley) are made from 2024 heat treated aluminum alloy which is viciously intolerant of any transverse crack. Hartzells may be a slightly different alloy but the crack sensitivity is certainly similar.

The science of crack propagation is in the realm of "fracture toughness". It was first explored after experience with the BOAC Comet tragedies in the 50s.

Any aluminum propeller is almost 1/8 inch larger in diameter due to centrifugal stress at takeoff rpm than it is standing still. It is a non-redundant item which is NOT a trivial item to be repaired with body putty.
 
nrpetersen said:
Absolutely it is junk!!!

It is conceivable if the nick was blended out per the manufacturers spec that it would again pass...
Click to expand...

That nick looks to be so deep as to be beyond the manufacturers width minima. There is only so much one can remove at any particular station along the blade.
 
That prop needs to be converted into beer cans. Anyone that flys it is a fool and anyone that sells it is a criminal.
 
I'm guessing that this is a composite blade with a damaged lead edge. The "filler" is the underlying composite material.
 
Paulie said:
That prop needs to be converted into beer cans.
Click to expand...

Or...

14907091388_3e81cf682f_z.jpg


Off of my Tiger after it measured out of limits on an annual. Hanging proudly in our living room.
 
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