Wood propeller maintenance/refurbishing
 

The 16 year old Clark Lydic Performance propeller on my RV-3B have some black spots. Is that mold from moisture that has somehow made its way below the urethane finish? Perhaps through minute cracks in the finish from rock strikes?

Also, along the trailing edges the urethane has begun to lift off.

Obviously it could be sent back to the manufacturer for refurbishing. But there must be some skill to be learned on how to maintain and refurbish a wood propeller.

I assume that one needs to sand down spots to the bare wood and then apply multiple layers of spar varnish.

Anybody here have experience in this field and any tips?

Finn

Give me a call Monday and I'll be happy to walk you through the steps and tell you what tools you will need.
713-417-2519

Edit: please don't use spar varnish

Why not spar varnish?

Spar varnish will work, but, it takes a while to dry( some brands take days), its soft and not durable as other products, just dosen't have a nice looking gloss to it. Yeah, I'm being picky. And, If you're investing the time to do it right, make it look good and last.

I use PPG DCU2002, it's a high solids clear and can be wet sanded and polished the day after you shoot it. Which is helpful to get an exact balance.

I can vouch for Frank?s work. Put over 300 hours on his prop rain or sleet or UV not a dent in clear coat.

Prop
 

I have a Aymer-DeMuth prop on my 180 HP RV4 that I would like to balance. But before I balance it I would like to sand it down and refinish it.

Then a static balance.

Then do a Dynamic balance on the engine while running.

Are there any links to doing the the sanding and finishing? Then a link on static balancing our selves?

For the dynamic balance, I will get an AME with the equipment to do it.

Thanks

Sorry, No links for this. Maybe one day soon I'll do a couple YouTube vids for folks.

Basically, I sand down to carefully remove the old finish and no wood, static balance then start reapplying clear, between each coat of clear rebalance. If I do my job right I have applied the clear evenly enough that it balances perfectly after last application.

The nice thing about the PPG DCU2002 is it can be wet sanded the day after shooting to achieve balance, if the blade is a bit out of blance, then polished to a nice shine.

Also the tracking is checked during the process, this is important to keep tracking within 1/16th of an inch , preferably less, for you will get a vibration from an out of track prop.

If you have the static balance right and the track within tolerance, a Dynamic balance is not necessary.

Hope this helps

Thanks for all the data Frank.

I forgot to ask, or missed, what grit sandpaper do you use to get rid of the old varnish?

Do not want it to take forever but also don't want to get into the wood.

Finn

[quote=FinnFlyer;1387694]Thanks for all the data Frank.

I forgot to ask, or missed, what grit sandpaper do you use to get rid of the old varnish?

Do not want it to take forever but also don't want to get into the wood.

Finn,
I start with 80 grit to remove the old finish, then 120 to smooth out, then 180 between coats, except last one I use medium scotch brite.
Good luck

Remember to check and re-torque your prop often (as wood shrinks and expands with moisture. You have to have proper crush plate(s) I recall. Van's "RVator" articles decades ago had many articles about wood props; many more folks were flying with them. In rain slow way down RPM and AS.

Exactly right! But remember, not all wood props are created equally. Torque will vary with the density of the wood type and thickness. The multi-laminate can be torqued at a much higher value than a plank prop.

Crush plates should match the diameter of the crank flange, or in the case of RVs , the extension. 7" is preferred over 6". Especially for 150HP and up applications.

In rain, as long as you have good leading edge protection, normal cruise settings are acceptable.