Thread by @chainsawrocks

The engine idle speed control is used to prevent stall during idle. The goal-to idle at as ⬇️ RPM as possible yet keep it from running rough/stalling when power-consuming accessories - air conditioning and alternators, turn on
Q. How many engine idle’s are there for CFM56 #A320 ?

• Reverse Idle ( approx.70% N2 )
= Approach Idle + 1000 RPM FADEC sets the engine speed at reverse idle when the throttle is set in the reverse idle detent position.

• Approach idle (approx.70% N2)varies as a function of Total Air Temperature (TAT and altitude)
This idle speed is selected to ensure sufficiently short acceleration time to go around thrust & is set when the a/c is in an approach configuration. (Flap Lever Position -" NOT UP")

• Minimum idle (58.8 % N2 ) is corrected for ambient temp >30°C Then the N2 will increase. The minimum idle should never be below 58.3% N2

• Bleed Idle = Bleed demand.
Bleed Idle command will set the fuel flow requested for ensuring correct aircraft ECS system pressurisation ,wing anti ice and engine anti ice pressurisation (Pb-"ON" or valves not closed)

IDG Idle Bias (Min Idle - Approach Idle) = The min idle speed will increase to maintain the engine oil temperature within max limits( in flight only ),when the engine oil temperature reach > 106 deg C (signal from TEO sensor).The speed can increase up to approach idle.

• Weather Idle Speed-On the ECU software P28/P15 (SB 73-131) .This eliminates the FCOM requirement that the 🧑‍✈️ must manually select Nacelle AntiIce prior to penetrating moderate to heavy precipitation wx conditions in order to establish the min idle to 45% N1(reduces🧑‍✈️work load)