CFR > Title 14 - Aeronautics and Space > CHAPTER I—FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION > SUBCHAPTER C—AIRCRAFT (parts 21 to 50) > PART 33—AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES > SUBPART C—Design and Construction; Reciprocating Aircraft Engines (§33.31 to §33.39) > 33.37—Ignition system.

33.37—Ignition system.

Each spark ignition engine must have a dual ignition system with at least two spark plugs for each cylinder and two separate electric circuits with separate sources of electrical energy, or have an ignition system of equivalent in-flight reliability.