View all text of Subpart J [§ 121.211 - § 121.295]
§ 121.251 - Engine accessory section diaphragm.
Unless equivalent protection can be shown by other means, a diaphragm that complies with § 121.247 must be provided on air-cooled engines to isolate the engine power section and all parts of the exhaust system from the engine accessory compartment.