A propulsion unit for an aircraft, comprising a nacelle and a turbojet engine, said propulsion unit comprising: - a stationary unit, - at least one cowl pivotally mounted on an axis substantially collinear with a longitudinal axis of the propulsion unit, between an operation position and a maintenance position enabling access to the turbojet engine for regular maintenance operations and non-regular maintenance operations, said non-regular maintenance operations requiring an opening angle of said cowl, relative to its operation position, larger than the opening angle of said cowl required to carry out regular maintenance operations, - at least one cylinder secured to the movable cowl and secured to the stationary unit by means of a main fitting mounted on the stationary unit, when said cowl is in the operation position and in the maintenance position enabling access to the turbojet engine for regular maintenance operations, - at least one safety connecting rod secured to the movable cowl and secured to the stationary unit by means of said main fitting, when said cowl is in the operation position and in the maintenance position enabling access to the turbojet engine for regular maintenance operations, wherein: - the cylinder is sized to enable an alternative passage of the cowl between an operation position and a maintenance position enabling access to the turbojet engine for regular maintenance operations only, - the safety connecting rod is sized to hold the cowl in the maintenance position enabling access to the turbojet engine for regular maintenance operations only, - the main fitting is sized to enable regular maintenance operations only, and in that it comprises a secondary fitting to be mounted on the main fitting for non-regular maintenance operations only, said secondary fitting being sized to enable non-regular maintenance operations and supporting said cylinder disconnected from the main fitting and said safety connecting rod disconnected from the main fitting when the cowl is in a maintenance position enabling access to the turbojet engine for non-regular maintenance operations. - a stationary unit, - at least one cowl pivotally mounted on an axis substantially collinear with a longitudinal axis of the propulsion unit, between an operation position and a maintenance position enabling access to the turbojet engine for regular maintenance operations and non-regular maintenance operations, said non-regular maintenance operations requiring an opening angle of said cowl, relative to its operation position, larger than the opening angle of said cowl required to carry out regular maintenance operations, - at least one cylinder secured to the movable cowl and secured to the stationary unit by means of a main fitting mounted on the stationary unit, when said cowl is in the operation position and in the maintenance position enabling access to the turbojet engine for regular maintenance operations, - at least one safety connecting rod secured to the movable cowl and secured to the stationary unit by means of said main fitting, when said cowl is in the operation position and in the maintenance position enabling access to the turbojet engine for regular maintenance operations, - the cylinder is sized to enable an alternative passage of the cowl between an operation position and a maintenance position enabling access to the turbojet engine for regular maintenance operations only, - the safety connecting rod is sized to hold the cowl in the maintenance position enabling access to the turbojet engine for regular maintenance operations only, - the main fitting is sized to enable regular maintenance operations only,