787 APU on for takeoff?
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Join Date: Mar 2006
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787 APU on for takeoff?
Hi,
Why do the 787 crews seem to leave the APU on for takeoff? I've noticed it with AeroMexico, LAN and LOT.
http://www.airliners.net/photo/LOT--...ner/2470243/L/
Why do the 787 crews seem to leave the APU on for takeoff? I've noticed it with AeroMexico, LAN and LOT.
http://www.airliners.net/photo/LOT--...ner/2470243/L/
Join Date: Sep 2013
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After engine start APU is switched OFF, then 3 minutes after the APU switch to be in ON Position to allow APU Door to open to increase cooling, after takeoff APU switch to OFF.
Join Date: Aug 2007
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On the ground, when the APU inlet door is closed after APU shutdown, hot air can collect in the APU. The hot air can cause a rotor imbalance or bowed rotor. In rare cases, a bowed rotor can cause rotor rub that might lead to a hung start and APU damage.
To prevent a bowed rotor hung start on the ground, the APU door should be kept open for at least 40mins after APU shutdown. This prevents hit air from being trapped in the APU and allows the APU to be started at any time with no risk of a bowed rotor hung start.
If takeoff occurs during the 40min wait, the APU door can be closed at a convenient time after takeoff.
To prevent a bowed rotor hung start on the ground, the APU door should be kept open for at least 40mins after APU shutdown. This prevents hit air from being trapped in the APU and allows the APU to be started at any time with no risk of a bowed rotor hung start.
If takeoff occurs during the 40min wait, the APU door can be closed at a convenient time after takeoff.
Join Date: Jun 2001
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Could be APU-to Packs procedure.
Join Date: Sep 2013
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how ARE the batteries doing these days?
To prevent a bowed rotor hung start on the ground, the APU door should be kept open for at least 40mins after APU shutdown