42 moves the stairway assembly 37 within the service bay from an access position indicated in solid lines to a non use stored position as shown in broken lines a collapsible stair handrail assembly 44 has a pair of spindles 45 a and 45 b pivotally secured to the stringer 39 and to a rail 45 referring now to fig5 and 6 of the drawings a tensioning and release mechanism 46 inner engages the stair spindle 45 b having a central hub 47 with a pair of annularly offset engagement arms 48 and 49 extending therefrom an elongated coil spring 50 extends from a bracket 51 on the bay floor 13 around the hub 47 within a spring guard 52 to a link 53 that pivotally extends from the end of the hereinbefore described engagement arm 48 a deployment cable 54 is adjustably secured to the end wall 14 of the service bay 10 and to a link 55 pivoted to the engagement arm 49 with the stair assembly in open access position the spring 50 is expanded applying tension to the engagement arm 48 and against the deployment cable 54 as the piston and cylinder assembly 43 pushes the stairway back to its stored position shown in broken lines tension on the cable 54 releases and the spring 50 rotates the hub 47 via the engagement arm 48 pivoting the stair spindle 45 b in a clockwise direction as.