Protective device for the air intake of a jet engine

The device has a protection cover (32) with a main portion (34) to seal an inlet (14) of a fan case ducting (12) when the device is assembled on an air inlet structure (6) of a jet engine. The cover has a secondary portion integrated with the main portion, where the secondary portion has rigidifying unit and covers partially a hood (8) to seal a ventilation flap (20).