Image Number 2 for United States Patent #4086670.
This invention relates to an aircraft toilet drain assembly of the type utilizing a drain plug, intended to prevent a maintenance operator from failing to replace the drain plug at the completion of after-flight servicing. The assembly is installed at the end of an outlet tube from a toilet holding tank in a position adjacent an access opening in the aircraft, which is closed in flight by an access panel. The assembly includes an outlet nipple, secured to the outlet tube, and a releasable cover mountable on the end of the nipple. A handle mounted on the cover is selectively movable between an extended position in which it obstructs the access opening to prevent the access panel from being closed and a depressed condition in which the access panel can be closed. An interlock responsive to the presence of the drain plug in the nipple locks the handle in its extended position unless a drain plug is present. The toilet drain assembly thus ensures that the aircraft access panel cannot be closed and the aircraft cleared for flight, unless a drain plug has been installed.