rib tail mod

[tx_swordguy]

Guys I realize this is an avid flyer not a kitfox but was hoping you could help me out. I have made an aluminum angle plate that was attached to both sides of my rib tail to reinforce the tails. The aluminum is .032 and I riveted it with 3 , 3/16" blind pop rivets as I understood the Kitfox sb9 to require blind rivets but didn't see a call for a particular type. I didn't know the difference in rivets and just got open end pop rivets that break the mandrel off inside the rivet. They are already installed and bonded with adhesive. My question is with my condition inspection coming up in the next 2 months do I need to drill all that out and start with closed end rivets for the extra stregnth of the mandrel? or will an A+P be ok with what I have on the plane as is? Sorry the pics got rotated when downloading to the site. The 1/4" angle that goes out from the rib is on the bottom of the rib just for clarity. Thanks guys
ps after I did all that and it really stiffened up the ribs I started getting nervous about it affecting a clean inspection. Its my first plane and first conditional coming up.

[rv9ralph]

If those pull rivets are aluminum, they are not structural. You need structural pull rivets, they are available from Aircraft Spruce.

I would not trust those rivets, without retaining the mandrel, the rivet will with time be compressed from the sides making it loose in the hole and working loose altogether.

Ralph

[PapuaPilot]

Here are a couple of options. You could replace them with solid aircraft rivets. You could do it with AN screws, nuts and washers just like the ones in the picture. Both of these would be acceptable, but bucking 3/16" rivets would be challenging. Personally I would replace them with some AN526 structural screws.

[avidflyer]

Here is my take on it. In reality, the ribs were strong enough as they were provided they weren't rotted or hit with something. Not saying that you shouldn't have put the stiffeners on them though. Secondly, the glue if done well and correctly will probably be plenty strong without the rivets. Thirdly, no real reason to tie up a 5 lb dog with a 3/4" diameter rope. How much force will ever be put against the rivets? Very little or none if the glue is doing it's job. I wouldn't worry about the AnP's inspection. Don't mention the stiffeners at all. He probably will walk right by them and not notice. JImChuk

[David47]

I agree with Jim Chuck. Also bear this in mind: pop type rivets, including those we use in Kitfox, have mandrels that are held in by friction. Over time and with vibration, structural movements etc, mandrels don't necessarily stay in place, ie they can work loose and fall out. But your instal has adhesive as well so, as long as your surface prep was good, the adhesive will do the job.

[HighWing]

One more agree with Jim. By coincidence I have an Avid Mk 4 resting in front of my hangar and inspecting it my thinking is you wI'll be fine with your mod as it is. As suggested, don't point anything out to the AP and let him go his own way. Regarding the rivets. It has been my experience when riveting to enhance or secure a glued joint, enough adhesive will be on the nub of the rivet to glue the mandrel in place - shouldn't work loose.