jaradtke
Well Known Member
I painstakingly drilled out 310 rivets on my outboard upper wing skin, (don?t ask me why) using the procedure outlined by Walt Aronow , drill the head, break the head off, pop the rivet tail out. I didn?t even remove the tails until the skin was removed. It was easy enough to just pull them out from the backside. I?m thinking ?That wasn?t so bad.?
Ok?here is the dilemma I?m faced with. According to MIL-R-47196A, 3.2.1.3. Hole size. Hole size for rivets shall conform to Table I unless otherwise specified on the engineering drawing or specification. Table 1 calls out the min/max for a 3/32 rivet as .093/.103 respectively.
I used a #37 drill bit with a diameter of .104 as a no go gage, I figured if it fit through the hole I f?ed up and would have to use a NAS1097 rivet. The first thing I did was check all 75 of the machine counter sunk holes on the wing spar flange. The #37 drill bit didn?t fit in any of them, yea for me. Next I checked the dimpled rib holes and, son of a!@#$ , it went through every single one of them.
Contemplating the horror in front of me, I got to thinking, sometime that?s a bad thing, what?s the size of a newly dimpled #40 hole? So I grabbed some scrap .025, the same thickness as the ribs, and drilled a nice crisp #40 hole and dimpled it with spring back dimple dies. Low and behold the #37 passed right through.
3.4.1. Oversize rivet holes. When rivet holes are enlarged beyond specified tolerances, the next larger rivet size (diameter) may be used provided the row spacing, pitch and edge margin minimum are maintained and the requirements of paragraph 3.4.3 are not exceeded?.
I call an A&P I know and explained my dilemma. He said I was overthinking the issue. And told me to use NAS1097 rivet if I was concerned. However Section 3.4.3. Repair limitations. The combined oversize rivet hole repairs and oversize countersink repairs shall be limited to a maximum of 20 percent of the rivets, or 10 rivets in a single rivet pattern, whichever is less. Repairs to more than two adjacent oversize rivets, or replacing more than half the rivets with oversize rivets in any 10 inch length of pattern is prohibited.
That many reduced rivet head on the low pressure side of the wing causes me pause.
Am I overthinking this?
Ok?here is the dilemma I?m faced with. According to MIL-R-47196A, 3.2.1.3. Hole size. Hole size for rivets shall conform to Table I unless otherwise specified on the engineering drawing or specification. Table 1 calls out the min/max for a 3/32 rivet as .093/.103 respectively.
I used a #37 drill bit with a diameter of .104 as a no go gage, I figured if it fit through the hole I f?ed up and would have to use a NAS1097 rivet. The first thing I did was check all 75 of the machine counter sunk holes on the wing spar flange. The #37 drill bit didn?t fit in any of them, yea for me. Next I checked the dimpled rib holes and, son of a!@#$ , it went through every single one of them.
Contemplating the horror in front of me, I got to thinking, sometime that?s a bad thing, what?s the size of a newly dimpled #40 hole? So I grabbed some scrap .025, the same thickness as the ribs, and drilled a nice crisp #40 hole and dimpled it with spring back dimple dies. Low and behold the #37 passed right through.
3.4.1. Oversize rivet holes. When rivet holes are enlarged beyond specified tolerances, the next larger rivet size (diameter) may be used provided the row spacing, pitch and edge margin minimum are maintained and the requirements of paragraph 3.4.3 are not exceeded?.
I call an A&P I know and explained my dilemma. He said I was overthinking the issue. And told me to use NAS1097 rivet if I was concerned. However Section 3.4.3. Repair limitations. The combined oversize rivet hole repairs and oversize countersink repairs shall be limited to a maximum of 20 percent of the rivets, or 10 rivets in a single rivet pattern, whichever is less. Repairs to more than two adjacent oversize rivets, or replacing more than half the rivets with oversize rivets in any 10 inch length of pattern is prohibited.
That many reduced rivet head on the low pressure side of the wing causes me pause.
Am I overthinking this?