This AIR is intended to assist in evaluating the serviceability of damaged hydraulic tubing lines. The performance requirements are outlined to which the defect samples were tested. Test methods and data are described and summarized to assist in further work toward establishing limits for defects in aircraft hydraulic tubing. Permissible defect limits are listed for 6061T6 aluminum return lines, 3000-psi hydraulic tubing of 21Cr-6Ni-9Mn as well as 304 1/8 hard corrosion resistant steel (CRES), and 3Al-2.5V cold-worked (CW) titanium.