Crack in flange on nose rib

[parish]

I have not been on much lately with the change of employment but progress has been progressing slowly. I have completed all my flap, aileron, and back ribs. Also completed all the aileron pocket and nose ribs and flap nose ribs. No problems there.

I began flanging the nose ribs and I noticed last night that 4 or 5 of them developed a crack in the flange on the top side. It is not full thickness and with substantial time (7 -10 min) I am able to buff it out on the scotchbright wheel. I am assuming this is happening when I put too much bend before the flutes get put in. Most of these "cracks" are very close to where the rivet will go to hold the skin to the rib. One fell in the flute.

In the picture below, the bottom rib is without making any changes, the top one is after a few min on the scotchbright wheel. I was able to completely buff it out flat after a few more minutes.

So the question to the group, should I scrap these and redo them or am I safe to simply buff them out. m

[jaredyates]

In the picture it's hard to tell which marks are bothering you- is it the ones that are parallel to the flutes?

[Dlarabee]

In my opinion if you have any doubt that it will fail it is better to just remake the part for your own piece of mind.

[parish]

yes Jared, the marks that are parallel to the flutes

[S Lathrop]

Is there a chance that the fluting pliers are causing the cracks?

[Chris In Milwaukee]

And is it actually a crack (I have cracked ribs), or is it just a mark from the fluting pliers?

[DRLPatrol]

If it is real crack how can you buff it out?

Doug

[parish]

It is not from the fluting pliers. The "mark" comes after I flange the outside edge before putting in the flutes. It is not a full thickness crack but appears to be the top 10% or so of the material. obviously deep enough for me to get a nail into. There is no evidence on the bottom side that there is anything going on above. I did honest to goodness crack a lightning hole on a flap rib and that was full thickness and I tossed that one out obviously.

Using the engineering side of my brain, I ask myself what are the loads being applied? during flight in this particular area. The answer is downward vectors about 30-45 degrees of the spar. I think as long as I clean them up real good, they will be ok assuming a rivet is not going directly through the mark area. These are also the 1/8" shortened ribs so they are way out towards the end of the wing and it will be 2 on each side (there are 4 of them that developed this issue).

Thanks for the replies guys

[Chris In Milwaukee]

My fluting pliers did the same thing: put a mark on the outside of the rib in that same spot. I do plan to scotchbrite them down before priming, I think I'll also grind down the surface of the fluting pliers, too, to minimize that from happening again.

[parish]

DISASTER AVERTED!!!!

I figured out what was causing it. When I flanged the top first, then flipped them over in the vice, the top was making contact with a sharp point on the jaw of my vice. My jaws are not that deep so it was easy for this to happen.....whew, buff it out and off I go!