koopas
Aerospace
- Aug 24, 2002
- 106
Hello again,
Here's the repair scenario involving a 2-inch long "T" section extrusion made from 7075-T6511, 0.100" thick.
The horizontal flanges of the "T" are attached to the airplane belly skin with two Hi-Loks on each side of the vertical flange. So, all four Hi-Loks are loaded in tension.
Now, the vertical leg of the "T" has two protruding head Titanium tension Hi-Loks loaded in shear that hold part of the lower wing-to-body fillet fairing. Both Hi-Lok holes possess the factory 2D+0.06 ED, and the holes are intact. However, corrosion was found AROUND one of holes on the extrusion's surface, between the hole and the leg's edge. In other words, corrosion was found in the edge distance "area" of one of the fastener holes. The local thickness remaining around that hole after blending out the corrosion is now 0.070".
Can you justify using the part as-is, or would you scrap the part and order a new one? What would be your methodology and substantiation in disposing of this discrepancy?
My main concern is that the bearing allowable of that Hi-Lok in the 7075 extrusion just plummeted since the bearing thickness was reduced by 30%. How can one still show this condition acceptable for strength? Or is it a lost cause?
Alex
Here's the repair scenario involving a 2-inch long "T" section extrusion made from 7075-T6511, 0.100" thick.
The horizontal flanges of the "T" are attached to the airplane belly skin with two Hi-Loks on each side of the vertical flange. So, all four Hi-Loks are loaded in tension.
Now, the vertical leg of the "T" has two protruding head Titanium tension Hi-Loks loaded in shear that hold part of the lower wing-to-body fillet fairing. Both Hi-Lok holes possess the factory 2D+0.06 ED, and the holes are intact. However, corrosion was found AROUND one of holes on the extrusion's surface, between the hole and the leg's edge. In other words, corrosion was found in the edge distance "area" of one of the fastener holes. The local thickness remaining around that hole after blending out the corrosion is now 0.070".
Can you justify using the part as-is, or would you scrap the part and order a new one? What would be your methodology and substantiation in disposing of this discrepancy?
My main concern is that the bearing allowable of that Hi-Lok in the 7075 extrusion just plummeted since the bearing thickness was reduced by 30%. How can one still show this condition acceptable for strength? Or is it a lost cause?
Alex