Aviation Mechanic - General, Airframe, and Powerplant › II. Airframe › Task H. Aircraft Instrument Systems

AM.II.H.K9

Knowledge

Instrument vacuum and pneumatic systems.

Study note

Get a short, cited explanation of this element written from the FAA handbooks: the core idea, the numbers that matter, common test traps, and a quick self-check.

From the FAA library

Instrument Flying Handbook p. 5-17
Chapter 5: Flight Instruments › Gyroscopic Systems › Pneumatic Systems
obtained by evacuating the instrument case with a vacuum source and allowing filtered air to flow into the case through a nozzle to spin the wheel. Venturi Tube Systems Aircraft that do not have a pneumatic pump to evacuate ... instruments through filters built into the instrument cases. In this system, ice can clog the venturi tube and stop the instruments when they are most needed. Figure 5-27. A venturi tube system that provides necessary vacuum to operate…
Instrument Flying Handbook p. 5-17
Chapter 5: Flight Instruments › Gyroscopic Systems › Electrical Systems
instrument failure. Direct current (D.C.) electrical instruments are available in 14- or 28-volt models, depending upon the electrical system in the aircraft. A.C. is used to operate some attitude gyros and autopilots. Aircraft with only D.C. electrical systems ... instruments via installation of a solid-state D.C. to A.C. inverter, which changes 14 or 28 volts D.C. into three-phase 115-volt, 400-Hz A.C. Figure 5-28. Single-engine instrument vacuum system using a steel-vane, wet-type…
Instrument Flying Handbook p. 5-17
Chapter 5: Flight Instruments › Gyroscopic Systems › Vacuum Pump Systems
Steel vanes sliding in a steel housing need to be lubricated, but…