StacksVerified U.S. regulatory reference

14 CFR §121.245

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
Each engine, auxiliary power unit, fuel-burning heater, or other item of combustion equipment that is intended for operation in flight must be isolated from the rest of the airplane by means of firewalls or shrouds, or by other equivalent means.