What is the weird noise they make when they get to the gate and before the push back? It's almost like pump? Or a tightening noise? Anyone know what I mean?
Full Version: Airbus A319 Noise
QUOTE(cshine877 @ Mar 30 2009, 12:03 PM) 
What is the weird noise they make when they get to the gate and before the push back? It's almost like pump? Or a tightening noise? Anyone know what I mean?
Quoting one of the famous and wise 27driver phrases, "that's the industry sucking you dry"
Most propable it is the Power Transfer Unit (PTU)
From Wikipedia :
" The purpose of the Power Transfer Unit (PTU) is to produce hydraulic pressure in the left hydraulic system in the event of a left hydraulic system engine-driven pump failure.
The PTU is used when there is right hydraulic system pressure but no left hydraulic system pressure. It transfers hydraulic power from the right hydraulic system to the left hydraulic system. There is no intermixing of hydraulic fluid between the left and right hydraulic systems during PTU operation. The PTU is able to operate the hydraulic motor generator during all phases of flight.
On the Airbus A320 family of aircraft, during engine startup or shutdown, a distinctive noise (sometimes known as the "barking" noise, because the noise resembles a dog barking) can be heard inside the aircraft when the PTU is used."
Listen at the sound in the beginning of this video :
http://www.youtube.com/watch?v=grd5eJjJcL4
From Wikipedia :
" The purpose of the Power Transfer Unit (PTU) is to produce hydraulic pressure in the left hydraulic system in the event of a left hydraulic system engine-driven pump failure.
The PTU is used when there is right hydraulic system pressure but no left hydraulic system pressure. It transfers hydraulic power from the right hydraulic system to the left hydraulic system. There is no intermixing of hydraulic fluid between the left and right hydraulic systems during PTU operation. The PTU is able to operate the hydraulic motor generator during all phases of flight.
On the Airbus A320 family of aircraft, during engine startup or shutdown, a distinctive noise (sometimes known as the "barking" noise, because the noise resembles a dog barking) can be heard inside the aircraft when the PTU is used."
Listen at the sound in the beginning of this video :
http://www.youtube.com/watch?v=grd5eJjJcL4
That must be the one. Interestingly, the one I last flew on decided to bark continuously for about 1-2 minutes after we stopped at our stand. That's a loud one too...
QUOTE(Kilrah @ Mar 31 2009, 02:28 PM)
That must be the one. Interestingly, the one I last flew on decided to bark continuously for about 1-2 minutes after we stopped at our stand. That's a loud one too...
It could also be the cargo door on the right which is operated by the yellow system, being hydraulically operated but with an electrical pump for the yellow (right) hydraulic system. . . . pump. (nearly!)
Or, the PTU.
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I just had a listen, to the vid. To be honest, it must be Trim. It is obviously not the cargo door as you are already pushing back. It has got to be trim - if not it is one helluva big dog in the hold!
Whadda you pilots say. . ?
I recently flew several times during the past week, lots of flights with easyJet on A319's (Also got an ex GB Airways A320! G-TTOF) I heard the noise during every startup, and on the A320, it went continously for a fair few minutes after arrival at the gate.
I always though it was hydraulics being switched on/off. Pilot, probably engineer would be able to answer better.
I always though it was hydraulics being switched on/off. Pilot, probably engineer would be able to answer better.
Yeah- I always remember hearing it on a US Airways A321 that I was on a few years back.
THERE IS NEVER AN ENGINEER AROUND WHEN YOU NEED ONE!!!!!
Well, don`t strain yourseleves!!!
Well, don`t strain yourseleves!!!
Yes, it is the PTU.
I am no longer 100% sure how it works but if memory serves me right, this is how it is:
During start-up of the second engine (Engine 1 when it is a normal automatic start), the PTU makes a self-test that lasts about 10 seconds IIRC.
After engine shutdown the PTU is de-energized which makes the "barking" noise slow down because both green and yellow systems slowly depressurize.
When you activate the Yellow Electric Pump from the overhead panel (or when a cargo door is opened from down under), the sound of the pump is actually a loud and high-pitched noise.
You cannot hear both noises from the cockpit, but you'll most likely hear them in the cabin, especially if your sitting near the overwing emergency exits.
When dead-heading in the passenger cabin, we would sometimes tell curious passengers (as a joke of course) that there was carpenter in the cargo compartment opening the cargo doors with a saw.
Hope this helps.
I am no longer 100% sure how it works but if memory serves me right, this is how it is:
During start-up of the second engine (Engine 1 when it is a normal automatic start), the PTU makes a self-test that lasts about 10 seconds IIRC.
After engine shutdown the PTU is de-energized which makes the "barking" noise slow down because both green and yellow systems slowly depressurize.
When you activate the Yellow Electric Pump from the overhead panel (or when a cargo door is opened from down under), the sound of the pump is actually a loud and high-pitched noise.
You cannot hear both noises from the cockpit, but you'll most likely hear them in the cabin, especially if your sitting near the overwing emergency exits.
When dead-heading in the passenger cabin, we would sometimes tell curious passengers (as a joke of course) that there was carpenter in the cargo compartment opening the cargo doors with a saw.
Hope this helps.
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