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Aft flap skin - RV-8

Webb

Well Known Member
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The bottom aft flap skin looks like the wind would catch and lift it which could potentially bend the skin.

Plans show no rivet near edge to prevent wind from lifting the skin. I’m getting ready to mix some Proseal for another use and while I have a batched mixed, why not glue the skins together so the wind can’t lift it.

Is this the way to go or is there something better to do?
 
The bottom aft flap skin looks like the wind would catch and lift it which could potentially bend the skin.

Plans show no rivet near edge to prevent wind from lifting the skin. I’m getting ready to mix some Proseal for another use and while I have a batched mixed, why not glue the skins together so the wind can’t lift it.

Is this the way to go or is there something better to do?

Or just follow the assembly instructions and not try to fix a problem that doesn't exist.
 
Yup - 1612 RV-8’s flying, and I have never heard of anyone with a problem with the flap design…..

However, I would change the flap push rods to the hexagonal version used in the RV-9. Also use a CM-4M rod end bearing with appropriate bolts/washers instead of the CM-4S. I also might consider changing out the hinge type to MS200001 instead of MS20257 (AN257)...

...but that's about it... ;)
 
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Since. This is a pre-owned kit, I am going over every inch and rivet.
According to the plans, the more aft layer lays on top and what is here agrees with the plan drawings.

Could this be a problem if wind gets under the skin which it quite possible. I’m looking at what could be a potential problem.
 

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You are going to trim this overhang during final assembly when you fit the flap to the wings. The overhang is the extra stuff that will be trimmed off per the plan. Don’t over think it because a few thousands RVs can fly just right
 
Understand the top gets trimmed. Unless I missed it, bottom does not look like it does, and potential for air lifting the bottom skin seems possible.

Not trying to over think it. Just will have an extra dab of Proseal and looks like a good place to put it and make sure skin can’t lift up when flaps deployed.
 
This is the other side. Sure looks like a good use to keep the skins together.

This isn’t my work. I’m just the repairman.
 

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You're right to be concerned.

The attached photos show a crack in the lower skin of my right hand flap that originated at the inboard most rivet that ties the two skins together on the bottom of the flap. I first noticed it a few weeks ago after almost a year and 100 hrs since my 8 first flew. I believe the airflow was separating the lap joint in flight and causing the top skin (that's on the bottom of the lap joint) to flex repeatedly, causing it to crack.

Van's support told me to stop drill the end of the crack but that would mean drilling into the inboard rib so I did what you suggested and applied some adhesive inside the lap joint. I also installed two additional rivets in the lap joint inboard of the crack to prevent it from flexing in the future. I did this on both flaps.
 

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