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A320 APU

Old 22nd Sep 2021, 15:27
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Join Date: Mar 2013
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A320 APU

Why this change in N% (Honeywell 131-9)

The ECB always sets the APU speed to 100 % except for air conditioning demand, if the ambient temperature is between -18 C and 35 C. In this case, the ECB sets the APU speed to 99 %. For all other ambient temperatures (less than -18 C or more than 35 C), the ECB sets the APU speed to 100 %.


On the APS3200



In the case of an automatic, non-emergency shutdown, the air inlet flap closes 15 min after the APU speed is lower than 7%. If an automatic, non-emergency shutdown happens on ground, the 15 min countdown starts after liftoff.

Why the delay ?
B737NG_Pilot is offline  
Old 23rd Sep 2021, 21:25
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I have no experience with A320, but just from the general principles, flap closure may be delayed to let the APU turbine cool down properly.
Ultranomad is offline  
Old 25th Sep 2021, 06:44
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Join Date: Mar 2021
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737NG Pilot, never seen that delay on ground on A320. There is max 2 min cooldown cycle before APU shuts down (depends on bleed usage). Inlet flap closes immediately after APU rpm is less that 7%. Where did you find information about 15 minutes delay and could you please insert a quote from a document here? Could you also tell what do you mean under automatic shutdown? There is no automatic shutdowns on APU - it is either normal, protective or emergency.
Acie is offline  

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