Mechanical accessory horsepower
Mechanical accessory horsepower means the sum of mechanical horsepower generated by an engine to supply accessories. Mechanical accessory horsepower does not include power supplied to the main alternator or generator, power used to circulate engine coolant or engine lubricant, or power used to supply fuel to the engine.
40 CFR § 92.2
The definitions of this section apply to this subpart. They also apply to all subparts of this part, except where noted otherwise.