flaperon rib tail reinforcement ?

[tx_swordguy 20]

Guys,

I am in the process of trying to reinforce the rib tail/ flaperon hanger. I am using .032 aluminum with a 1/4" 90 degree  angle bent on the bottom side. The repair will have the angle on the bottom of the rib tail instead of on the top like the kitfox is done. I am doing it that way because my avid (don't know about others) has a scalloped top side and a straight bottom to the rib tail. Anyway, my question is in doing this mod I have increased the width of the end of the rib by .064" and I currently have 5mm screws with an unthreaded grip length of about .346" and would like to find a 5mm screw with an unthreaded grip length of .400-.450" and cannot find any thing like that at any online suppliers (cant even find my original screws anywhere). Here is my question. My 3 options are 1. use original screws WITHOUT washers. 2. Use standard all thread type screws.. 3 drill a bigger hole and use 8mm screws with the proper grip that I can find. If I do not use washers I will have the steel flaperon hanger on the outside of the aluminum plates so the screw head and nut will be against the steel hanger. ( not fond of the lack of washers but....) If I use the standard all thread screws I can use the washers but I am not fond of the idea of the thread chewing up any material between the screw head and the nut. Option 3 drilling a bigger hole concerns me (maybe overly so) because in trying to reinforce the ribs I would be taking material away. Maybe I am overly cautious since this plane has been flying as is for over 20 yrs.

[akflyer 1427]

I am not sure why you have metric on there.  The ones for the Avid are all standard and can be purchased from Spruce. 

http://www.aircraftspruce.com/catalog/hapages/an525.php

 

This is what I have in mine, pretty sure they are 10/32.

 

[tx_swordguy 20]

thanks. I think I may have figured it out with the nas623 screw. Dang these specs are confusing when they just don't give dimensions . Went ahead and made a second order with the ones you suggested just to be safe. Thanks again AK

 

Edited 15 May 2017 by tx_swordguy

[tx_swordguy 20]

while we are on this subject I bought some bonderite 1201 (used to be alodine 1201) to put on the aluminum to help with the epoxy adhesion to the rib along with the rivets. It says you can just paint right on top of it as if it were a regular primer (thinking that is for enamel or paint designed for composites/metal airframes. I am reading that poly tone has issues on aluminum. Has anyone put polytone over the bonderite coating? Should I put an additional primer on prior to painting the polytone?  I have used self etching primer on aluminum followed by enamel in the past and worked fine. Problem is the polytone is not enamel and I want this to match the rest of the plane. How did everyone else paint their aluminum rib reinforcements?

[LSaupe 123]

I used aerothane with no problems.

[1avidflyer 1983]

Poly fiber says to use an epoxy, and just as the epoxy is getting tacky, shoot the poly tone.  They also sell enamel that is supposed to match poly tone colors.  JImChuk