DA recommends torquing the 4 prop bolts on a DA50 to 55 in-lbs. I was thinking of using a drop of "Blue Loc-Tite" on each bolt before torquing. What do you guys think? The first time I removed the prop that was torqued to spec I noticed that there was an impression in the wood face of my prop from the aluminum plate, is that normal? Also the bolts seemed easy to back off. The engine has only been run twice (about 30 ozs of gas). Do any of you add lock washers?

WW2 Ace,

I don't use loc-tite on the Prop Bolts, just about every where else though. No lock washers either, but I do use #10 stainless steel )thin) washers to protect the aluminum prop washer. Impressions on a wood prop is normal and you might even find a slight mark or two on a carbon fiber prop. Typically you'll want to check the prop bolts after the first two flights and then maybe again after ten flights. Don't over tighten, they'll break and normally below the threaded surface. Let DA take it out if happens or unless your a machinist, drill and a easy out works.
Other GS Pilots will have other comments I'm sure.



DA recommends torquing the 4 prop bolts on a DA50 to 55 in-lbs. I was thinking of using a drop of "Blue Loc-Tite" on each bolt before torquing. What do you guys think? The first time I removed the prop that was torqued to spec I noticed that there was an impression in the wood face of my prop from the aluminum plate, is that normal? Also the bolts seemed easy to back off. The engine has only been run twice (about 30 ozs of gas). Do any of you add lock washers?
[/quote]

Dont use Loc tight on prop bolts!

Wood props must be re-torked from time to time as they compress. More so when they are new.

Place a washer under the head of the bolt to prevent galling of the aluminum prop washer.

I fully agree with both of the two posts above.

Thats a good thing...I got that advise from you a while back.....

Somehow I know its not a good idea to use locktite. Something about a bolt shearing off in my DA 100. I have used just a scosh of locktite on the DA 50 before. For my Tru Turn spinner most def. Other than that just check your bolts before your flying session or here or there.

Well, I say Use Locktite and lockwashers. I have been using BLUE (medium strength) locktite and lockwashers now for 2 years on my DA engines. No problems getting them off when I need them off. It's added insurance that doesn't cost allot. It doesn't harm any component just use it sparingly.

My method for applying it is simple.

Run the bolt through the lockwasher, a thin steel washer, the thrust plate, the prop and then the spinner backplate. Now apply a drop of locktite and wipe off excess with your finger. Bolt on prop. DO NOT use a rag or towel on the threads this will remove to much compound. By using your finger you remove excess and leave just enough to do the job. This is a mount it and forget it method. I have never needed to retighten bolts nor have I ever had a prop come loose.

Having an impression in the wood is perfectly normal after removing the prop.

Yeah, this is pretty much a judgement call. I have never used loctite or washer and never had a problem, but I do check my bolts regularly.

Some food for thought:

In three different sizes of 3W engines used on some unmanned stuff, both singles and twins, with all the aircraft flying for numerous continuous hours at a time, no Locktite has been used on the prop bolts. That's for both plastic and wood props. There has never been a need evidenced. All the bolts and/or nuts are properly torqued to the manufacturers suggested rating. BTW, that's about 40 inch pounds if I recall correctly.

If you're using a wood prop as mentioned in an earlier post it will need to be re-tightened periodically and the use of Locktite will make that difficult. You would also have the need to chase the old Locktite out of the threads each time you re-tightened the bolts and reapply the stuff all over again. If the threads are not as clean as possible Locktite will not bond all that well anyway.

Use it if you want, but I can't see the benefit.

1. No need to go and retorque. Like I said, Mount it and forget it.
2. A little more security can't be a bad thing.
3. How long does it take to apply that drop? Not more than a second.

FWIW, allot of the newer UAVs are using Safetywire on the prop bolts. No need for locktite when using safety wire To be honest this is a method I would probably consider on larger engines.

Basically, you do what you think you need to do and I will do my method. They both seem to work just fine.

I have 2 DA 50's and never has even 1 prop bolt come loose..not even a little..I do use the thin steel washers and just snug them up

Dont forget to recheck the bolts at the begining of every season. The wood can dry on the off season and actually shrink making the bolts loose. I had to digg the busted ends out of my hub at the beginning of the season.

Digging out broken bolts is one of the reasons I would not use any thread lock on the prop bolts. I've had to cut off frozen bolts and stripped soft metal bolt heads from far too many 3W motors. To have to remove them with a thread lock applied to them makes me shudder with trepidation. At the same time I kinda agree with Ken that you can go either way with the stuff, depending on your preference.