New ACS - Cessna Wing Spar

[Skymaster337B]

I own an Eddy Current machine that is specified in the Cessna Service Bulletin, which the AD refers to. There's a few problems not addressed either before or now. First, it is important that Cessna provide a sample that the machine can be calibrated against; there is no reference to this, nor does Cessna have a part number for the required calibration sample. Additionally, most of the bolt holes in the front spare caps are threaded, making the inspection some what subjective.