Boiling Propellers

Thank you.

pkrankow wrote:.........
Search DAM nylon if you want more.  That is "Dry As Molded" and not a curse upon the nylon.

Phil

Some people say nylon is already a curse word in itself, the abbreviation for "Now You Lousy Old Nippon"  that went into use during WW2 when the silk, produced by Japan, and used for stockings and parachute canopy production in the US, became unavailable for the US given its state of war with Japan, proclaimed after Pearl Harbor...and then in need for a substitute material  DuPont invented nylon...but this may just be some urban legend..

If you think the prop is brittle, I would personally discard them. My flying partner insisted on doing the same thing and ended up with a prop blade through his cheek. He has a scar about 4" long down his face. After the surgery and 2 attempts to remove the scar that developed a keloid, I figured that was just over $10,000. That being the worst incident, I've seen a lot of minor ones compared to that that all due to brittle prop use. Is it worth the risk for something that costs $2 ?

some light history
https://en.wikipedia.org/wiki/Nylon


I agree with Ken that a questionable prop should not be used and instead discarded (I had a stack of old white Top Flight props that were brittle before boiling, and just as brittle after boiling).

Nylon becomes more flexible when "wet" internally. It does however loose a small amount of strength when "wet" internally. The net result is that in some cases the prop will perform better in a prop strike situation and not break.

I do not boil all my props. I have boiled my new manufacture Cox "rubber ducky" props, and I am unsure if there was practical improvement. The new manufacture props are supposed to be "conditioned" with moisture after manufacture, so there is no need to boil.

Phil

These are new Cox props that came with a boil before use note. I will try to do it this week. Thank you for the help, advice, and concerns. All taken note of.

How do you determine if the prop is still too bridle to use or unsafe ? I know I have some old ones from engines that I am sure are 30 yrs. old and would never consider them or ones with worn edges where it looks like they been into the concrete !

One symptom is when you slightly bend the blade you will see thin cracks and crevises on the surface..You do not want to use this brittle one...

With the white Top Flite props I grabbed a blade and bent it. They were a flexible prop that should have bent easily and returned to shape like a Cox "rubber ducky" prop. They broke with little deflection. I had some "good" props that were supple and flexible, but ebay provided me with over a dozen junk props. After boiling the junk props were still junk. After sitting for several weeks in a plastic bag with added water they were still junk.

Phil

Great. Thanks for the pics. I will take a look and evaluate now that I know what to look for.

I will also comment, that while his example shows the cracks in the blade it doesn't show the root at the hub. This is where a immediate failure will occur and with no warning or visible signs.