I found that buying a new foot-pound Kobalt torque wrench at Lowe's each spring is the cheapest and quickest way to comply with AC43.13-1B. The wrench comes with a certificate of calibration and saves me the time and hassle of shipping it off for re calibration. As a reminder:AC 43.13-1B, 7-40. TORQUES
The importance of correct torque application cannot be overemphasized. Undertorque can result in unnecessary wear of nuts and bolts, as well as the parts they secure. Overtorque can cause failure of a bolt or nut from overstressing the threaded areas. Uneven or additional loads that are applied to the assembly may result in wear or premature failure. The following are a few simple, but important procedures, that should be followed to ensure that correct torque is applied. …
Calibrate the torque wrench at least once a year, or immediately after it has been abused or dropped, to ensure continued accuracy.
Although the regulation only requires “accepted industry practices” be used, the advisory circular explains that the FAA interprets that to mean that all torque wrenches, force gauges, and other tools should be calibrated annually.