XVII Emergency Locator Transmitter (ELT)..................11-65 Long Range Aid to Navigation System  (LORAN) ...............................................................11-67 Global Positioning System (GPS) ..........................11-69 Wide Area Augmentation System (WAAS).......11-70 Inertial Navigation System (INS)/Inertial  Reference System (IRS).............................................11-71 Installation of Communication and Navigation  Equipment ..................................................................11-72 Approval of New Avionics Equipment  Installations ............................................................11-72 Considerations ........................................................11-72 Cooling and Moisture.............................................11-73 Vibration Isolation..................................................11-73 Reducing Radio Interference .....................................11-74 Shielding.................................................................11-74 Isolation ..................................................................11-74 Bonding ..................................................................11-74 Static Discharge Wicks ..........................................11-74 Installation of Aircraft Antenna Systems...................11-75 Transmission Lines ................................................11-76 Maintenance Procedure ..........................................11-76 Hydraulic and Pneumatic Power Systems......12-1 Aircraft Hydraulic Systems..........................................12-1 Hydraulic Fluid ............................................................12-2 Viscosity...................................................................12-2 Chemical Stability ....................................................12-2 Flash Point................................................................12-3 Fire Point ..................................................................12-3 Types of Hydraulic Fluids ...........................................12-3 Mineral-Based Fluids ...............................................12-3 Polyalphaolefin-Based Fluids...................................12-3 Phosphate Ester-Based Fluid....................................12-3 Intermixing of Fluids................................................12-3 Compatibility with Aircraft Materials......................12-4 Hydraulic Fluid Contamination................................12-4 Contamination Check ...........................................12-4 Contamination Control .........................................12-5 Hydraulic System Flushing ......................................12-5 Health and Handling.................................................12-6 Basic Hydraulic Systems .............................................12-6 Open Center Hydraulic Systems ..............................12-6 Closed-Center Hydraulic Systems............................12-7 Hydraulic Power Systems ............................................12-7 Evolution of Hydraulic Systems...............................12-7 Hydraulic Power Pack System .................................12-7 Hydraulic System Components ................................12-8 Reservoirs .............................................................12-8 Chapter 12 Filters......................................................................12-13 Micron-Type Filters............................................12-14 Maintenance of Filters ........................................12-14 Filter Bypass Valve ............................................12-14 Filter Differential Pressure Indicators ................12-14 Pumps .....................................................................12-15 Hand Pumps ...........................................................12-15 Power-Driven Pumps .............................................12-16 Classification of Pumps ......................................12-16 Constant-Displacement Pumps...........................12-17 Gear-Type Power Pump .....................................12-17 Gerotor Pump......................................................12-17 Piston Pump ........................................................12-17 Vane Pump..........................................................12-20 Variable-Displacement Pump.............................12-20 Valves.....................................................................12-22 Flow Control Valves...........................................12-22 Pressure Control Valves .....................................12-27 Shuttle Valves.....................................................12-30 Accumulators..........................................................12-31 Types of Accumulators.......................................12-31 Heat Exchangers.....................................................12-32 Actuators ................................................................12-33 Linear Actuators .................................................12-33 Rotary Actuators.................................................12-34 Hydraulic Motor .................................................12-34 Ram Air Turbine (RAT).........................................12-34 Power Transfer Unit (PTU)....................................12-35 Hydraulic Motor-Driven Generator (HMDG)........12-35 Seals .......................................................................12-35 V-Ring Packings.................................................12-36 U-Ring ................................................................12-36 O-Rings...............................................................12-36 Backup Rings......................................................12-37 Gaskets................................................................12-37 Seal Materials .....................................................12-38 O-Ring Installation .............................................12-38 Wipers.................................................................12-38 Large Aircraft Hydraulic Systems .............................12-38 Boeing 737 Next Generation Hydraulic System ....12-38 Reservoirs ...........................................................12-38 Pumps .................................................................12-40 Filter Units ..........................................................12-40 Power Transfer Unit (PTU) ................................12-40 Landing Gear Transfer Unit................................12-42 Standby Hydraulic System .................................12-42 Indications...........................................................12-42