Control of engine rotation.
CFR · 2024-01-01 · US · Title 14
(a) Except as provided in paragraph (b) of this section, each airplane must have a means of individually stopping and restarting the rotation of any engine in flight. (b) In the case of turbine engine installations, a means of stopping the rotation need be provided only if the Administrator finds that rotation could jeopardize the safety of the airplane.
official document · source cfr-2024 · id 14:§ 121.279