Aircraft drainage valve, tool for checking the correct operation of said drainage valve and method for checking the operation of said drainage valve using said checking tool

A drainage valve comprising:

• a support configured to be fixed against an inner face of a wall in line with an orifice passing through the wall,
• a ring having a through hole and a seat around the through hole, configured to be positioned at the orifice,
• a shutter comprising an end face delimited by a peripheral edge, wherein the end face is proximate to the seat of the ring, said shutter being movable in a longitudinal direction between a first position in which the end face of the shutter is away from the seat of the ring and a second position in which the end face of the shutter is pressed against the seat of the ring and blocks the through hole,
• an elastic element configured to keep the shutter in the first position as long as a differential between pressures on either side of the wall is below a given threshold,
• wherein the shutter has a cylindrical body and a recess emerging on its through the end face of the shutter, said recess being spaced apart from the peripheral edge over an entire circumference of said peripheral edge, said recess comprising a lateral wall that is cylindrical and substantially coaxial to the cylindrical body of the shutter.