49 CFR §193.2517
Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
When necessary for safety, components that could accumulate significant amounts of combustible mixtures must be purged in accordance with a procedure which meets the provisions of the “Purging Principles and Practices (incorporated by reference, see § 193.2013)” after being taken out of service and before being returned to service.