gear leg fairing hinges: to glue or not to glue? (-7TD)

[rv7charlie]

No joy searching archives here & matronics, so here goes:

What's the word on using glue/adhesive on the main gear leg fairing hinges? Is there enough risk of the rivets 'working' as the FG flexes to justify gluing the hinges like the cowl hinges?

If so, what's the best compromise of convenience & quality? epoxy? Urethane? Other? I've already drilled them to the fairings & don't want to use anything that's too thick & will push the trailing edges apart.

Thanks,

Charlie

[uk_figs]

I just completed this task on my -7 and searched the archives for hints, clues etc. Many people use the expanding foam which "glues" the fairing to the leg as the tab approach seems prone to breakage. I decided to do the same and the net result is that the foam extruded through the rear hinge effectively gluing the whole thing together, I trimmed it off when it was set.
Based on how it sets up I imagine it will be a bear to remove the fairings if I ever need to do that (I have the bonaco flex brake hoses with the protective cover) but I figure I will just make new pieces if this happens.
It sure does not seem like these fairing will be going out of alignment any time soon as they are solid.
I did fly before I did the foam to make sure the fairings were aligned properly.

[rv7charlie]

Ahh, yes, the GS foam would glue the hinge pretty effectively. :-)

Did you have shimmy issues prior to using the foam? If so, did the foam work well to damp the shimmy?

I like the idea of foam, but I'd still like to hear from those who didn't foam the fairings on whether they had rivets work in the 'glass if they didn't use glue under the hinges. Both the -4's I've owned had aluminum leg fairings, so I can't really look there for help.

Thanks,

Charlie

[DakotaHawk]

Yep, I've got my fuselage suspended (to take the weight off of the mains) and got the wheel pants and gear fairings fitted in place. Next to do is align the gear fairings and then build up the intersection fairings.

I bought an 8' length of trim wood today for gear leg shimmy damper (per plans), but if the Great Stuff foam works, I'd rather use the foam solution.

Does the foam work to stop shimmy? or is it just a filler to hold the gear fairing in place in relation to the gear?

[uk_figs]

I have not noticed shimmy to be a problem during take-off and the initial landing phase, I do get a shimmy or judder occasionally when taxiing or when braking on landing roll-out. I am not sure if this is the gear legs or possibly the tail wheel as I have a similar issue on my Pacer every once in a while.
I have not had the opportunity to fly since the final foam (crappy weather in Utah lately) to check if the situation is improved.

[uk_figs]

One other quick point about the great stuff foam is that it does not set up very well in low humidity and low temperature which just happens to be the current environment here in Utah and it remains sticky, to resolve this I had to raise the temperature (used a local heater) and mist the inside of the fairing with water. They have a pro version that work at lower temperatures but I could not find it in the usual Home Depot/Lowes stores.
Another tip to remember is on the -7 many people cut the top forward gear leg fairing at an angle to make cowling removal easier, I did this after marking the position of the Van's upper intersection fairing and then switched to the Fairings Etc fairings as I did not like the quality of the Van's fairings. The Fairings Etc. top intersection fairings do not come as far down the leg so the angle cut is just barely inside the fairing.

[SteinAir]

The general consensus from the graybeard over the years is to avoid the foam. It's a mess all the way around, especially down the road if/when you need to work on them. It also traps moisture which steel doesn't like, does nothing for dampening to speak of and just doesn't really get you much of anything in the end, except lots of cussing years down the road.

Gear leg stiffners...I've built 'em both ways. Again the general opinion is/has been to not put them on unless you find out you need them (which most RV's don't, but some do). More time, more weight, stiffer gear, and again unless you need them little to no real advantage. All of our RV's live on rough grass, spend 99% of their time on grass and have been for over 10 years with no ill effects other than the standard tailwheel issues and lots of minnesota bugs!

We've built/worked on a lot of RV's new and old and I really can't say anything nice about foamed in fairings.

My 2 cents as usual.

Cheers,
Stein

[Scott Hersha]

My former RV-6 has about 600 hours on it and there is no issue with the hinge rivets working loose. The paint is still in excellent shape. I bonded wood door trim stiffeners to the legs with fiberglass, but I think it is unnecessary unless you operate off grass on a regular basis. I had no shimmy on pavement, but have observed round-leg RV's wheel shimmy while taxiing on grass - no big deal in my opinion. My RV-8 leg fairing hinges are riveted on per plans. Glueing/bonding the leg fairing on would make brake line service or future paint touch-up much more difficult.

Scott
RV-8 Fastback

[JonJay]

Originally Posted by SteinAir

The general consensus from the graybeard over the years is to avoid the foam. It's a mess all the way around, especially down the road if/when you need to work on them. It also traps moisture which steel doesn't like, does nothing for dampening to speak of and just doesn't really get you much of anything in the end, except lots of cussing years down the road.

Gear leg stiffners...I've built 'em both ways. Again the general opinion is/has been to not put them on unless you find out you need them (which most RV's don't, but some do). More time, more weight, stiffer gear, and again unless you need them little to no real advantage. All of our RV's live on rough grass, spend 99% of their time on grass and have been for over 10 years with no ill effects other than the standard tailwheel issues and lots of minnesota bugs!

We've built/worked on a lot of RV's new and old and I really can't say anything nice about foamed in fairings.

My 2 cents as usual.

Cheers,
Stein

Worth more than 2 cents. I have seen the corrosion on a neighbors gear legs as a direct result of the foam trapping moisture. He was able to salvage the gear but it was very close to ruining them.
I did glue my cowling hinges with surplus Beoing epoxy. Cant remember but dont think i did on my gear leg fairings. ProSeal also works very well. Still, not an issue that I have heard of on gear leg fairings.

[osxuser]

I third it, foam is the easy solution, but trouble down the road. Proseal and riveting should keep the the rivets from working in the glass. Also use soft (A) rivets instead of AD, they will have less tendency to crack the matrix of the glass because they take less pressure to set.