Planet carrier for a mechanical gearbox on an aircraft turbomachine

A planet carrier for a mechanical gearbox of a turbomachine for an aircraft, the planet carrier comprising:

• a main axis;
• a cage formed in a single piece, the cage comprising:
• a shaft portion centred on the main axis;
• first and second annular flasks extending around the main axis, the first flask being operably coupled to the shaft portion, and the second flask being operably coupled to the first flask by bridges of material distributed around the main axis, the bridges of material defining between them and with the first and second annular flasks;
• and
• housings configured to receive planet gears, the first and second flasks comprising, respectively, a plurality of first and second orifices for mounting the planet gears, each of which are oriented axially and which open into the housings,
• wherein the first flask comprises a thinning around each of the plurality of first orifices, the thinning defining a minimum thickness of material in the axial direction which is less than a minimum thickness of the second flask around each of the plurality of second orifices, and wherein the thinning comprises two or three coaxial gorges extending around each of the plurality of first orifices.