CFR > Title 40 - Protection of Environment > CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY > SUBCHAPTER C—AIR PROGRAMS (Parts 50–99) > PART 91—CONTROL OF EMISSIONS FROM MARINE SPARK-IGNITION ENGINES > SUBPART B—Emission Standards and Certification Provisions (§91.101 to §91.126) > 91.109—Requirement of certification—closed crankcase.

91.109—Requirement of certification—closed crankcase.

(a) An engine's crankcase must be closed.
(b) For purposes of this section, crankcase means the housing for the crankshaft and other related internal parts.