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, <EOS>