RVM

I just installed some DuBro HD 40-91 control horns on an ARF (Fliton Extra 330) and after I had them set, I noticed that it crushed the mount point a bit (about 1cm thick balsa or something - hard to tell on an ARF - might have been balsa sandwiched between some very thin hardwood). After I had drilled the holes for them I hardened the area with thin CA. They're on there tight right now, but should I or will I have to replace these mounts in the future? Is this anything to be concerned about right now? Should I go ahead and replace them now? Bleh I'd hate to do that.

Thanks!

alan0899

G'day Mate,
Sounds fine to me, I always seem to crush the mounts a bit, keeps everthing tight when you need it. just check it after first flight, as I'm sure you do with everything on a new plane, It should be fine.

Newc

Seems to me that there's no hardwood between the mounting washers. Is there any? Did you add any? Hardeneing with CyA is fine for a lightweight control horn on a solid balsa surface, or for strengthening a screw thread, but not for a single bolt control horn like the DuBro HD .91 (catalogue #913) horns. Before flying it I would make sure - a simple test 'wiggle' - that the horns are not just tight, but that you aren't able to further deform the mounting area by holding the horn and trying to move the control surface with a fairly strong arm.

RVM

Yeah I tried the wiggle test. It's very solid.

It's the first time I've done this as I tend to build most of my planes and use solid hardwood for horn mounts.

I guess I'll just fly like this and keep an eye on it.