Abstract: An adapter for coupling connecting pipes for a commercial aircraft comprises an adapter top and an adapter bottom. The adapter bottom has a first adapter pipe that can be positioned within a recess in a floor of the aircraft. An attachment flange is formed to the external circumference of the first adapter pipe, through whose central flange opening the first adapter pipe is led, which attachment flange is positioned on the first adapter pipe end of the first adapter pipe and is attached by one flange side to a bottom floor region of the floor. The adapter top has a second adapter pipe to which a tubular supporting flange is joined. The pipe end region reinforced with said supporting flange of the second adapter pipe is inserted into the pipe cross section of the first adapter pipe.