Advisory of Transportation U.S. Department Circular Federal Aviation Administration Subject: FUEL DRAIN VALVES Date: 2/7/83 AC No: 20-119 Initiated by: AWS-130 Change:
1. PURPOSE: This advisory circular provides an acceptable means, but not the only means, of compliance with the requirements of the Federal Aviation Regulations (FAR) for positive locking of fuel drain valves in the closed position.
2. BACKGROUND. FAR Sections 23.999(b), 25.999(b), 27.999(b), and 29.999(b) require, in part: Each drain. must have manual or automatic means for positive locking in the closed position. . . ." This requirement refers to the required drain valves. The purpose of this advisory circular is to respond to the question as to whether a spring loaded valve in the closed position could be considered a "positive locking valve."
3. GUIDANCE. Spring loaded fuel drain valves conforming to MIL-V-25023B or TSO-C76 or equivalent may be approved for those installations where the person operating the valve can visually confirm that the valve is closed, provided the applicant has shown that the valve will not open inadvertently under any foreseeable operating condition.
M. C. Beard Director of Airworthiness