[Code of Federal Regulations] [Title 14, Volume 2] [Revised as of January 1, 2003] From the U.S. Government Printing Office via GPO Access [CITE: 14CFR125.115] [Page 579] TITLE 14--AERONAUTICSAND SPACE CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PART 125--CERTIFICATION AND OPERATIONS: AIRPLANES HAVING A SEATING CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF 6,000 POUNDS OR MORE; AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT--Table of Contents 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.