a. The air is a perfect dry gas;
b The temperature at sea-level is 15°C;
c. The pressure at sea-level is 1.013250 x 105 Pa (29.92 in Hg) (1013.2 mbar);
d. The temperature gradient from sea-level to the altitude at which the temperature becomes
–56.5°C is 3.25°C per 500 m (1.98°C/1000 ft);
e. The density at sea level ρο , under the above conditions is 1.2250 kg/m3 (0.002378 slugs/ft3); for
the density at altitudes up to 15 000 m (50 000 ft) see Table 1.
NOTE: ρ is the density appropriate to the altitude and ρ/ρ ο the relative density is indicated by σ .
‘Authority’ means the competent body responsible for the safety regulation of Civil Aviation. (See IEM 1.1, Authority).
*‘Autorotation’ means a rotorcraft flight condition in which the lifting rotor is driven entirely by action of the air when the rotorcraft is in motion.
Auxiliary Power Units:–
Definitions applicable to auxiliary power units:–
a.
‘Accessory drives’ means any drive shaft or utility mounting pad, furnished as a part of the auxiliary power unit, that is used for the extraction of power to drive accessories, components, or controls essential to the operation of the auxiliary power unit or any of its associated systems.
b.
‘Auxiliary Power Unit (APU)’ means any gas turbine-powered unit delivering rotating shaft power, compressor air, or both which is not intended for direct propulsion of an aircraft.
c.
‘Blade’ means an energy transforming element of the compressor or turbine rotors whether integral or attached design.
d.
‘Compressor air’ means compressed air that is provided by the APU to do work whether it is extracted or bled from any point of the compressor section of the gas turbine engine or produced from a compressor driven by the APU.
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