Abstract: The present invention is a folding protective cover primarily for openings which are generally circular in shape, particularly the air inlet and exhaust ducts of a stopped turbo-engine as used by aircraft. The invention is comprised of a generally circular ring shaped frame which is made up of four arc shaped sections of approximately 90 degrees each. Three hinges are mounted between the sections in such a manner that the frame may be folded into an arc of approximately 90 degrees. Affixed to the outer edge of the frame is a resilient gasket and affixed across the center of the frame is a waterproof fabric panel.

Abstract: A residential digital logic circuit telephone system is provided for internal voice communications and digital interfaces control which enables two or more conventional twelve button touch-tone telephone devices to be used as a voice intercommunication system utilizing a single bidirectional conductor and for selectively actuating and controlling the operation of other electrical and electronic devices connected to the system from multiple remote locations. In a preferred embodiment of the system, two to five touch-tone telephones inside a residence may be actuated selectively by means of a ringing signal from any one of said telephones to another or all the other telephones by means of a single conductor bidirectional voice communication circuit arrangement which has been established between a calling telephone and a responding telephone. The intercom ringing system is distinct from the normal ringing signal from an incoming outside call.