Standpipe
A pipe sticking up in a tank or reservoir that allows part of the tank to be used as a reserve, or standby, source of fluid.
Aviation Maintenance Technician Handbook — Airframe, p. G-33
Also defined in 1 more source
A pipe which protrudes upward from the base of an oil tank and through which oil used for normal engine lubrication is drawn. In the event of a catastrophic leak when all oil available to the engine-driven pump is lost overboard, enough oil is available from an outlet below the standpipe to feather the propeller.
Aviation Maintenance Technician Handbook — Powerplant, p. G-26