(a) Prior to December 1, 2020, you must be in compliance with the emission limitation that applies to you at all times, except during periods of startup, shutdown, or malfunction (SSM) of your control device or associated monitoring equipment. On and after December 1, 2020, you must be in compliance with the applicable emission limitation at all times.

(b) If you must comply with the emission limitation, you must operate and maintain your engine test cell/stand, air pollution control equipment, and monitoring equipment in a manner consistent with safety and good air pollution control practices for minimizing emissions at all times. The general duty to minimize emissions does not require the owner or operator to make any further efforts to reduce emissions if levels required by the applicable standard have been achieved. Determination of whether a source is operating in compliance with operation and maintenance requirements will be based on information available to the Administrator that may include, but is not limited to, monitoring results, review of operation and maintenance procedures, review of operation and maintenance records, and inspection of the affected source.

(c) For affected sources prior to December 1, 2020, you must develop a written SSM plan (SSMP) for emission control devices and associated monitoring equipment according to the provisions in § 63.6(e)(3). The plan will apply only to emission control devices, and not to engine test cells/stands.