14 C.F.R. § 25.943 Negative acceleration.
Title 14 - Aeronautics and Space
No hazardous malfunction of an engine, an auxiliary power unit approved for use in flight, or any component or system associated with the powerplant or auxiliary power unit may occur when the airplane is operated at the negative accelerations within the flight envelopes prescribed in §25.333. This must be shown for the greatest duration expected for the acceleration. [Amdt. 25–40, 42 FR 15043, Mar. 17, 1977]
Title 14: Aeronautics and Space
PART 25—AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES
Subpart E—Powerplant
General
§ 25.943 Negative acceleration.