Carburetor air preheater design.
CFR · 2024-01-01 · US · Title 14
Each carburetor air preheater must be designed and constructed to— (a) Ensure ventilation of the preheater when the engine is operated in cold air; (b) Allow inspection of the exhaust manifold parts that it surrounds; and (c) Allow inspection of critical parts of the preheater itself.
official document · source cfr-2024 · id 14:§ 25.1101