Instrument  Range marking Airspeed indicator White arc bottom Top Green arc bottom Top Blue radial line Yellow arc bottom top Red radial line Carburetor air temperature Green arc Yellow arc Red radial line Cylinder head temperature Green arc Yellow arc Red radial line Manifold pressure gauge Green arc Yellow arc Red radial line Fuel pressure gauge Green arc Yellow arc Red radial line Oil pressure gauge Green arc Yellow arc Red radial line Flap operating range Flaps-down stall speed Maximum airspeed for flaps-down flight Normal operating range Flaps-up stall speed Maximum airspeed for rough air Best single-engine rate-of-climb airspeed Structural warning area Maximum airspeed for rough air Never-exceed airspeed Never-exceed airspeed Normal operating range Range in which carburetor ice is most likely  to form Maximum allowable inlet air temperature Normal operating range Operation approved for limited time Never-exceed temperature Normal operating range Precautionary range Maximum permissible manifold absolute  pressure Normal operating range Precautionary range Maximum and/or minimum permissible fuel  pressure Normal operating range Precautionary range Maximum and/or minimum permissible oil  pressure Instrument  Range marking Oil temperature gauge Green arc Yellow arc Red radial line Tachometer (reciprocating engine) Green arc Yellow arc Red arc Red radial line Tachometer (turbine engine) Green arc Yellow arc Red radial line Tachometer (helicopter) Engine tachometer Green arc Yellow arc Red radial line Rotor tachometer Green arc Red radial line Torque indicator Green arc Yellow arc Red radial line Exhaust gas temperature indicator (turbine engine) Green arc Yellow arc Red radial line Gas producer N1 tachometer (turboshaft helicopter) Green arc Yellow arc Red radial line Normal operating range Precautionary range Maximum and/or minimum permissible oil temperature Normal operating range Precautionary range Restricted operating range Maximum permissible rotational speed Normal operating range Precautionary range Maximum permissible rotational speed Normal operating range Precautionary range Maximum permissible rotational speed Normal operating range Maximum and minimum rotor speed for power-off operational conditions Normal operating range Precautionary range Maximum permissible torque pressure Normal operating range Precautionary range Maximum permissible gas temperature Normal operating range Precautionary range Maximum permissible rotational speed Figure 10-136.  Instrument range markings.  Maintenance of Instruments and Instrument  Systems rating to know what maintenance is required and to access  the approved procedures for meeting those requirements.  In the following paragraphs, various maintenance and  servicing procedures and suggestions are given. The  discussion follows the order in which the various instruments  and instrument systems were presented throughout this  chapter. This is not meant to represent all of the maintenance  required by any of the instruments or instruments systems.  The aircraft manufacturer’s and instrument manufacturer’s  approved maintenance documents should always be consulted  for required maintenance and servicing instructions. FAA  regulations must also be observed.  An FAA airframe and powerplant (A&P) technician is not  qualified to do internal maintenance on instruments and  related line replaceable units discussed in this chapter. This  must be carried out at facilities equipped with the specialized  equipment needed to perform the maintenance properly.  Qualified technicians with specialized training and intimate  knowledge of instruments perform this type of work, usually  under repair station certification. However, certified airframe technicians and A&P technicians  are charged with a wide variety of maintenance functions  related to instruments and instrument systems. Installation,  removal, inspection, troubleshooting, and functional checks  are all performed in the field by certified personnel. It is also  a responsibility of the certified technician holding an airframe  When an aircraft is to be operated under IFR, an altimeter test  must have been performed within the previous 24 months.  Altimeter Tests 10-83