40 CFR 89.306 - Dynamometer specifications and calibration weights.
(a) Dynamometer specifications. The dynamometer test stand and other instruments for measurement of power output must meet the accuracy and calibration frequency requirements shown in table 3 in appendix A of this subpart. The dynamometer must be capable of performing the test cycle described in § 89.410.
(b) Dynamometer calibration weights. A minimum of six calibration weights for each range used are required. The weights must be spaced to reflect good engineering judgement such that they cover the range of weights required and must be traceable to within 0.5 percent of NIST weights. Laboratories located in foreign countries may certify calibration weights to local government bureau standards.