IRImplementing rule
CS 25.991Fuel pumps
(a)Main pumps. Each fuel pump required for proper engine operation, or required to meet the fuel system requirements of this Subpart (other than those in sub-paragraph (b) of this paragraph), is a main pump. For each main pump, provision must be made to allow the bypass of each positive displacement fuel pump other than a fuel injection pump approved as part of the engine.
(b)Emergency pumps. There must be emergency pumps or another main pump to feed each engine immediately after failure of any main pump.
[Amdt 25/5]
IR · CS 25.991 — CS-25 · ED Decision 2008/006/R · CS-25 Easy Access Rules · EAR revision 26 Jan 2023