Text in force at CS25-28: from CS25-0, effective 17 Oct 2003.
No hazardous malfunction of an engine or any component or system associated with the powerplant may occur when the aeroplane is operated at the negative accelerations within the flight envelopes prescribed in CS 25.333. This must be shown for the greatest duration expected for the acceleration. (See also CS 25.1315.)
ED Decision 2003/002/RM · Source