Repower means replacement of the engine in a previously used locomotive with a freshly manufactured locomotive engine. Replacing a locomotive engine with a freshly manufactured locomotive engine in a locomotive that has a refurbished or reconditioned chassis such that less than 25 percent of the parts of the locomotive were previously used (as weighted by dollar value) is not repowering.
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.