[Code of Federal Regulations] [Title 14, Volume 2] [Revised as of January 1, 2008] From the U.S. Government Printing Office via GPO Access [CITE: 14CFR125.115] [Page 990] TITLE 14--AERONAUTICS AND SPACE CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PART 125_CERTIFICATION AND OPERATIONS: AIRPLANES HAVING A SEATING CAPACITY OF Subpart E_Special Airworthiness Requirements Sec. 125.115 Internal doors. In any case where internal doors are equipped with louvres or other ventilating means, there must be a means convenient to the crew for closing the flow of air through the door when necessary.