C-130H FS 477 Ext. Skin in C-130 Technical Posted October 31, 2017 Those look like drill chuck marks from when the holes were initially drilled in the structure. Structure technicians not paying attention and/or not using drill stops when drilling holes...just punching holes. Sad to say, not uncommon to see but typically of little concern unless in primary structure, i.e. longerons, end fittings etc where stress is high. In my 30 years experience as structural technician, I would not be too concerned about it, possibly blend out the deeper ones but that would be the extent of it, no straps etc. However, I don't work for your company and I'm not your engineer.