In this experiment we will measure the residual stress fields around two crack tips in 7xxx series aluminium alloy fracture specimens, along with the corresponding stress field prior to introduction of the cracks. The measurements will be used to verify a numerical method for calculating an upper bound for the stress intensity at a crack in an object containing an unknown distribution of residual stress. This method enables more accurate prediction of fracture for internally-loaded structures, and is broadly applicable in structural integrity assessment. The measurements made using SALSA will be compared with upper bound estimates of the stress intensity factor for this specimen geometry, which should provide experimental verification for the upper bound method.