Abstract: An aircraft fluid line coupling assembly includes: an inner tube; an outer tube assembly having an outer tube, the inner tube extending into the outer tube, and having first connector element of a twist-to-connect joint disposed on a front end of the outer tube; a retention member having second connector element of the twist-to-connect joint, the first and the second connector elements being detachably mated to releasably interconnect the retention member and the outer tube with each other, the retention member being arranged outwardly around a longitudinal portion the inner tube so as to prevent detachment of the inner tube from the outer tube when the twist-to-connect joint is in a connected position, and so as to allow detachment of the inner tube from the outer tube when the twist-to-connect joint is in an unconnected position; and a locking mechanism for locking the twist-to-connect joint.