DA=PA+/-120T
The DENSITY altitude changes dependant upon the temperature. The density of the air I.e. the mass per cubic meter as the temperature climbs. Therefore if the pressure altitude is corrected for excessive temperature the density altitude will climb and make the power from the engine less.
A gas turbine is not interested in how high it is it is interested in the masss gas flow through the combustion chamber and the cooling. If the mass per cubic meter reduces then the amount of 'burnable' air reduces, the amount of air required for cooling reduces and therefore the available power reduces and the operating temperature of the engine increases. IRRESPECTIVE of the pressure altitude.
Please note that the operating data for helicopters, especially the bigger aircraft, are calculated on density altitude.
So thanks for pointing my 'error' out and get back in the books.
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The amount of intake required by a gas turbine engine is approximately 10 times that required by a reciprocating engine. The air entrance is designed to conduct incoming air to the compressor with minimum energy loss resulting from drag or ram pressure loss, that is, the flow of air into the compressor should be free of turbulence to achieve maximum operating efficiency. Proper design con-tributes materially to aircraft performance by increasing the ratio of compressor discharge pressure to duct inlet pressure.
The amount of air passing through the engine depends on the--
Speed of the compressor RPM.
Forward speed of the aircraft.
*****Density of the ambient air.*****
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