Flight and Navigation Equipment  Miscellaneous Requirements  Helicopter Instrument Flight Rule (IFR)  Certification  Stabilization and Automatic Flight Control  System (AFCS)  • Stability Augmentation Systems (SAS) provide  short-term rate damping control inputs to increase  helicopter stability. Like trim systems, SAS requires  “hands-on” flying.  • Trim systems provide a cyclic centering effect. These  systems typically involve a magnetic brake/spring  device and may be controlled by a four-way switch  on the cyclic. This system requires “hands on” flying  of the helicopter.  • Aerodynamic surfaces, which impart some stability  or control capability that generally is not found in  the basic VFR configuration.  • Thunderstorm lights (transport category helicopters)  • Alternate static source (single-pilot configuration)  • Adequate ice protection of IFR systems  • Instrument power source indicator  • Overvoltage disconnect  • Speed warning device (if required by 14 CFR Part 29)  • Non-tumbling gyroscopic bank and pitch (attitude)  indicator  • Stand-by bank and pitch (attitude) indicator  • Magnetic gyroscopic direction indicator  • Rate-of-climb (vertical speed) indicator  • Free-air temperature indicator  • Magnetic direction indicator  • Sensitive altimeter (A “sensitive” altimeter relates to  the instrument’s displayed change in altitude over  its range. For “Copter” Category (CAT) II operations,  the scale must be in 20-foot intervals.) adjustable  for barometric pressure.  • Airspeed indicator  • Clock  The basic installed flight and navigation equipment for  helicopter IFR operations is listed under 14 CFR Part 29, §  29.1303, with amendments and additions in Appendix B of  14 CFR Parts 27 and 29 under which they are certified. The  list includes:  Helicopter manufacturers normally use a combination  of a stabilization and/or AFCS in order to meet the IFR  stability requirements of 14 CFR Parts 27 and 29. These  systems include:  These requirements are broken down into the  following categories: flight and navigation equipment,  miscellaneous requirements, stability, helicopter flight  manual limitations, operations specifications, and  minimum equipment list (MEL).  It is very important that pilots be familiar with the IFR  requirements for their particular helicopter. Within the  same make, model, and series of helicopter, variations in  the installed avionics may change the required equipment  or the level of augmentation for a particular operation. The  Automatic Flight Control System/Autopilot/Flight Director  (AFCS/AP/FD) equipment installed in IFR helicopters can  be very complex. For some helicopters, the AFCS/AP/  FD complexity requires formal training in order for the  pilot(s) to obtain and maintain a high level of knowledge  of system operation, limitations, failure indications, and  reversionary modes. For a helicopter to be certified  to conduct operations in instrument meteorological  conditions (IMC), it must meet the design and installation  requirements of Title 14 Code of Federal Regulations (14  CFR) Part 27, Appendix B (Normal Category) and Part 29,  Appendix B (Transport Category), which is in addition to  the visual flight rule (VFR) requirements.  Figure 7-1. Icing tests. To safely provide an all-weather capability  and flight into known icing conditions that would otherwise delay  or cancel winter flight operations, the digital control of the S-92  Rotor Ice Protection System (RIPS) determines the temperature and  moisture content of the air and removes any ice buildup by heating the  main and tail rotor blades. The system is shown here during testing.  7-2 