FAA AMT (Aviation Maintenance Technician) Airframe Practice Exam

A pressure reducer valve is used to lower the high pressure from the oxygen cylinder to a safe and usable level for the system. Option B, an oxygen concentrator, is not used to reduce pressure but rather to produce oxygen from ambient air. Option C, a pressure control regulator, helps maintain a steady pressure in the system but does not reduce the high cylinder pressure. Option D, an oxygen distributor, is responsible for delivering oxygen to different parts of the system and does not play a role in reducing pressure. Therefore, the correct answer is A, pressure reducer valve.