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BWIAirport
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A320 family aileron droop

Mon May 07, 2018 10:33 pm

Recently I have noticed A319, A320, and A321 aircraft's ailerons do not "droop" when parked at a gate or when the engines are shut off. Right now I'm at BWI and I can see an NK A320, A319, and WW A321. The A320 and A321 have sharklets and their ailerons are not drooping. The A319 has the old fences and they are drooping. Is that just a coincidence, or does either the wingtip device or aircraft model determine whether the ailerons droop?
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AirKevin
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Re: A320 family aileron droop

Mon May 07, 2018 10:37 pm

Pretty sure it's just a matter of whether the hydraulics are turned on or not.
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Antarius
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Re: A320 family aileron droop

Mon May 07, 2018 10:38 pm

I doubt the sharklets matter. Especially given they are a bolt on option for existing aircraft.

The droop is due to the hydraulic pumps being off. Is it possible that on some (the non drooping) the engines or APU were on?
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sixtyseven
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Re: A320 family aileron droop

Mon May 07, 2018 10:43 pm

No hydraulics equals droop. After engine shut down it takes a bit for the hydraulic pressure to dissipate and the ailerons will sag. You see it on Big Boeings as well the inboard ailerons will sag after hydraulics are removed post engine shut down.

APU does not supply hydraulic power. Only electrical and pneumatic.
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BWIAirport
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Re: A320 family aileron droop

Mon May 07, 2018 11:14 pm

Thank you for your answers
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thepinkmachine
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Re: A320 family aileron droop

Mon May 07, 2018 11:19 pm

I have noticed older airframes droop the ailerons earlier - perhaps seals getting worn, or something
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nws2002
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Re: A320 family aileron droop

Mon May 07, 2018 11:26 pm

sixtyseven wrote:
No hydraulics equals droop. After engine shut down it takes a bit for the hydraulic pressure to dissipate and the ailerons will sag. You see it on Big Boeings as well the inboard ailerons will sag after hydraulics are removed post engine shut down.

APU does not supply hydraulic power. Only electrical and pneumatic.


Dumb question maybe, but don't the cargo doors require hydraulic power? Or is that a completely separate system that uses an electric pump?

I've never had to ask for hydraulic power on the A320 series. We used to lower the aft stairs on the MD-80s though and then we'd frequently have to ask the flight deck for hydraulics to raise them again towards the end of the turn.
 
windy95
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Re: A320 family aileron droop

Mon May 07, 2018 11:30 pm

The ailerons are used for the Load Alleviation Function ( LAF) and when on the ground and not pressurized they may droop down to the servocontrol stop depending on wear.
 
windy95
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Re: A320 family aileron droop

Mon May 07, 2018 11:32 pm

nws2002 wrote:
sixtyseven wrote:
No hydraulics equals droop. After engine shut down it takes a bit for the hydraulic pressure to dissipate and the ailerons will sag. You see it on Big Boeings as well the inboard ailerons will sag after hydraulics are removed post engine shut down.

APU does not supply hydraulic power. Only electrical and pneumatic.


Dumb question maybe, but don't the cargo doors require hydraulic power? Or is that a completely separate system that uses an electric pump?

I've never had to ask for hydraulic power on the A320 series. We used to lower the aft stairs on the MD-80s though and then we'd frequently have to ask the flight deck for hydraulics to raise them again towards the end of the turn.


Yes the Cargo doors operate on a closed system and only pressurize when actuated.
 
sixtyseven
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Re: A320 family aileron droop

Tue May 08, 2018 12:16 am

nws2002 wrote:
sixtyseven wrote:
No hydraulics equals droop. After engine shut down it takes a bit for the hydraulic pressure to dissipate and the ailerons will sag. You see it on Big Boeings as well the inboard ailerons will sag after hydraulics are removed post engine shut down.

APU does not supply hydraulic power. Only electrical and pneumatic.


Dumb question maybe, but don't the cargo doors require hydraulic power? Or is that a completely separate system that uses an electric pump?

I've never had to ask for hydraulic power on the A320 series. We used to lower the aft stairs on the MD-80s though and then we'd frequently have to ask the flight deck for hydraulics to raise them again towards the end of the turn.


The cargo doors are powered by the yellow hydraulic system, and Is energized When the ground crew utilize the switch irrespective of whether the pump is powered by the flight deck controls. If the yellow system pump is inop the doors can be moved by a crank.
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Starlionblue
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Re: A320 family aileron droop

Tue May 08, 2018 1:11 am

Adding to the cargo door discussion, on the 330 they are also on the yellow system. With the engine driven pump off, the electric pump provides pressure when the cargo doors are operated. In order to isolate the cargo doors from the rest of the yellow system, thus ensuring the related flight controls are not powered, the yellow system leak measurement valve closes. If electric power is off, a hand crank can be used.
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