Sec. 23.959 - Unusable fuel supply.
(a) The unusable fuel supply for
each tank must be established as not less than that quantity at which
the first evidence of malfunctioning occurs under the most adverse
fuel feed condition occurring under each intended operation and flight
maneuver involving that tank. Fuel system component failures need not
(b) The effect on the usable fuel
quantity as a result of a failure of any pump shall be determined.
[Amdt. 23-7, 34 FR 13093, Aug. 13, 1969, as
amended by Amdt. 23-18, 42 FR 15041, Mar. 17, 1977; Amdt. 23-51, 61 FR
5136, Feb. 9, 1996]