Diamond DA 40 Flight Manual page 260

Airplane
Description
b) Long Range Tank
Fuel Tanks
Each of the two wing tanks consists of two (standard tank) or three (long range tank)
aluminum chambers which are joined by a piece of flexible hose and two independent
vent hoses. There are two separate vents per tank. The hose terminations are situated
on the underside of the wing, approx. 2 meter (7 ft) from the wing tip. One vent acts as
a capillary, both to equalize the air pressure, and to provide a safety factor in the event
of a failure of the other vent. The second vent is a check valve, to allow air to enter the
tank, but prevent flow to the outside.
Page 7 - 34 Rev. 8 01-Dec-2010
DA 40 AFM
Doc. # 6.01.01-E