Abstract: A multi-position latch mechanism is provided for a subsurface aircraft ground servicing chamber formed by a pit having an upright interior wall and a pit lid seat disposed atop the pit. A pit lid is provided which, when closed, rests upon the pit lid seat. The latch mechanism includes a catch member depending from the pit lid adjacent the upright wall of the pit. The catch member is mounted to the pit lid for rotatable movement relative thereto. A latching member is mounted on the upright interior pit wall and has a plurality of vertically spaced teeth that face the catch member. The catch member has a hook facing the latching member. The hook is alternatively engageable with each of the teeth, depending upon the extent to which debris on the pit lid seat holds the pit lid off of its pit lid seat.

Abstract: A subsurface aircraft servicing pit is provided with a hold down assembly that secures a pit lid mounting frame in position on a bearing seat at the top of a prefabricated pit enclosure. A frame mount latch ring is suspended in spaced relation beneath the underside of the pit lid mounting frame and inwardly from the walls of the pit enclosure. At least a pair of frame mount latches are provided on opposite sides of the pit. The latches have bases secured to the pit walls and hooks that extend over the top of the frame mount latch ring. The frame mount latches are constructed so as to exert a downward force on the frame mount latch ring, thus holding the peripheral margin of the pit lid mounting frame tightly against a peripheral bearing seat surrounding the pit opening. The necessary force exerted by the frame mount latches may be provided by a coil spring located within the structure of each frame mount latch.

Abstract: An aircraft servicing pit is provided that has a pit lid set within a supporting frame and hinged for rotation relative to a pit access opening. However, the pit lid is also completely detachable from the surrounding frame once it opened. The pit lid support has a flat deck surface with an access opening surrounded by a supporting rim located beneath the deck surface. A hinge pocket is defined in the structure of the pit lid support. A pair of hinge axle end slots are formed on the opposite sides of the pit lid support frame and are inclined upwardly and outwardly. The pit lid has a hinge leaf with a pair of hinge axle ends projecting transversely therefrom in opposite directions. The hinge axle ends engage the hinge axle end slots and are entrapped therein when the pit lid is closed.

Abstract: A multi-position latch mechanism is provided for a subsurface aircraft ground servicing chamber formed by a pit having an upright interior wall and a pit lid seat disposed atop the pit. A pit lid is provided which, when closed, rests upon the pit lid seat. The latch mechanism includes a catch member depending from the pit lid adjacent the upright wall of the pit. The catch member is mounted to the pit lid for rotatable movement relative thereto. A latching member is mounted on the upright interior pit wall and has a plurality of vertically spaced teeth that face the catch member. The catch member has a hook facing the latching member. The hook is alternatively engageable with each of the teeth, depending upon the extent to which debris on the pit lid seat holds the pit lid off of its pit lid seat.

Abstract: A latch assembly is provided for an aircraft service pit having a lid frame formed with an access opening encompassed within an upwardly facing bearing ledge. The pit lid has a flat upper surface and is hinged at one edge at a horizontal axis of rotation relative to the lid frame. The pit lid has an opposite, latching edge. A latch mechanism is mounted on the latching edge of the pit remote from the horizontal axis of rotation and includes a latch mount embedded in the structure of the pit lid. The latch mount defines a latch guide path inclined downwardly from the flat upper surface of the pit lid and outwardly toward the latching edge thereof. A latch bolt, preferably having a T-shaped handle, is reciprocally mounted for movement in the latch guide path. The latch bolt preferably has a gripping end formed as a T-shaped handle that is accessible from the flat upper surface of the pit lid. The latch bolt also has an opposite, distal, bearing ledge-engaging end.

Abstract: A buried subsurface pit for use beneath a surface across which aircraft travel for servicing aircraft is provided with a pit latching mechanism for holding and releasing a pit lid mounted atop the buried pit. A shallow latch operating lever storage recess is defined in the upper surface of the pit lid. An actuator rod passageway is formed in the pit lid and extends between the latch operating lever storage recess and the undersurface of the pit lid. A catch is located in alignment with the actuator rod passageway at the undersurface of the pit lid. The catch is mounted for rotation about a horizontal axis of catch rotation. An actuator rod is disposed for longitudinal, reciprocal movement in the actuator rod passageway. A latch operating lever has opposing latch handle and actuator rod engaging ends.

Abstract: A pit lid assembly is formed for a subsurface aircraft servicing pit and includes a lid frame formed with a flat, upper deck, a pit access opening surrounded by the deck, and a hinge pocket defined in the structure of the frame. The hinge pocket extends radially outwardly from the pit access opening and defines mutually opposing and mutually parallel pocket side walls. The pocket has a floor and an end wall slopes upwardly from the pocket floor at an obtuse angle relative to the surrounding flat deck of the frame. A pit lid is seated in the frame upon a bearing ledge formed about the periphery of the access opening. The pit lid has a hinge leaf projecting outwardly away from the access opening. Straight, narrow, linear bores are defined through the structure of both the hinge frame and the hinge leaf.

Abstract: An improved access lid assembly is provided for a subsurface chamber used to service aircraft. A lift assembly is provided for elevating the lid upwardly from an opening in a surrounding mounting frame disposed atop the subsurface chamber while maintaining the lid in a horizontal disposition. A hinge assembly connects the lift assembly to the lid at a peripheral location thereon on the underside of the lid, without any connection to the peripheral edge of the lid. The hinge assembly allows the lid to rotate about a horizontal axis to an open position through an arc of at least ninety degrees. By avoiding any connection to the peripheral edges of the lid, an elastomeric, annular seal can be mounted to completely encircle the lid and provide a water-tight barrier about the access opening. The seal is mounted between the upper and lower surfaces of the lid within a groove, preferably with a dovetail connection, to securely grip and hold the seal upon the edge of the lid.

Abstract: A closure apparatus for a subsurface pit for servicing an aircraft located beneath an aircraft servicing surface across which aircraft travel is provided with an improved spring biasing arrangement. The system employs separate springs interposed between the hollow body of the pit and the lid so as to urge the pit lid from its horizontal seated position toward a fully raised position. Obstructions are provided for separately intercepting and disengaging the springs from acting against the pit lid as the pit lid is opened through intermediate angular positions between the horizontal seated position and the fully raised position. By sequentially isolating the pit lid from the action of each of the springs, one at a time, the moment of spring force opposing closure of the lid more closely follows the moment of the force of gravity tending to close the lid. This substantially reduces the maximum manual force that is thereby required to overcome gravity in opening the pit lid.

Abstract: A subsurface chamber formed by a pit and buried beneath a surface across which aircraft travel is provided with an effective sealing system at its opening. The opening to the chamber is formed by a mounting frame adapted to receive and seat a lid therewithin. The mounting frame is formed with a frustoconical wall tapering downwardly and inwardly toward the opening into the chamber. The lid is provided with a peripheral rim having a plurality of flexible, resilient, annular, water impervious sealing flaps that extend outwardly from the lid an which are vertically spaced from each other. As the lid is lowered into position, the sealing flaps do not scrape or slide against the frustoconical wall of the mounting frame. Rather, they establish contact with the frame only as the lid approaches to within one quarter inch of its fully seated position.

Abstract: An aircraft servicing pit located beneath a surface across which aircraft travel while on the ground is provided with a ladder and a pair of reciprocally retractable handrails on each side of the ladder. Each of the handrails has an inverted "J-shaped" configuration. With the lid open the handrails can be drawn up out of the pit and rotated so that their legs can rest upon the tarmac surface at the edge of the pit. Service personnel utilizing the pit are thereby provided with stabilizing hand grips which enhance their safety when entering and leaving the subsurface chamber within the pit. When the pit is to be closed the retractable handrails are lifted, rotated, and lowered to their fully retracted storage positions.