AM.II.H.S11

From the FAA library

• Aviation Maintenance Technician Handbook - Airframep. 10-50
  Chapter 10: Aircraft Systems › Sources of Power for Gyroscopic Instruments › Pressure-Driven Gyroscopic Instrument Systems

  Figure 10-91. A typical pump-driven vacuum system for powering gyroscopic instruments. A schematic of this twin-engine aircraft vacuum system is shown in Figure 10-92. Note the following components: two engine-driven pumps, two vacuum relief valves ... flapper type check valves, a vacuum manifold, a vacuum restrictor for each turn and bank indicator, an engine four-way selector valve, one vacuum gauge, and a turn-and-bank selector valve. Not shown are system and individual instrument filters…

• Aviation Maintenance Technician Handbook - Airframep. 10-49
  Chapter 10: Aircraft Systems › Vacuum Systems › Twin-Engine Aircraft Vacuum System Operation

  minus sign is usually not presented, as the importance is placed on the magnitude of the vacuum developed. In relation to an absolute vacuum (0 psi or 0 "Hg), instrument vacuum systems have positive pressure. Figure 10-91 shows ... typical engine-driven pump vacuum system containing the above components. A pump capacity of approximately 10 "Hg at engine speeds above 1,000 rpm is normal. Pump capacity and pump size vary in different aircraft, depending on the number…

• Aviation Maintenance Technician Handbook - Airframep. 10-45
  Chapter 10: Aircraft Systems › Sources of Power for Gyroscopic Instruments

  Sources of Power for Gyroscopic Instruments Gyroscopic instruments are essential instruments used on all aircraft. They provide the pilot with critical attitude and directional information and are particularly important while flying under IFR. The sources of power for these instruments ... vary. The main requirement is to spin the gyroscopes at a high rate of speed. Originally, gyroscopic instruments were strictly vacuum driven. A vacuum source pulled air across the gyro inside the instruments to make the gyros spin. Later, electricity…