It’s common to hear a loud, repetitive whirring sound emanating from the floorboards of Airbus planes. Sometimes it’s a high-pitched whine; other times it’s a stilted WOOF, WOOF, WOOF, like the noise a very agitated dog might make. This pertains to twin-engine Airbus models: the A320 series (includes the subvariants A319 and A321) and the larger A330. In the United States, the largest operators of these types are Delta, United, JetBlue, and US Airways. Almost every frequent flyer has encountered this sound at one time or another. Crews rarely make efforts to explain it, leaving passengers befuddled and sometimes worried. Because the noise is akin to a motor repeatedly trying-and failing-to start, there’s often the assumption that something is malfunctioning. What you hear is a device called the power transfer unit, or PTU, which is designed to ensure adequate hydraulic pressures during single-engine operations. To conserve fuel, it’s fairly routine for two-engine planes to taxi with an engine shut down. Each engine normally pressurizes its own hydraulic system, but with a motor not running, that leaves one system without a power source. That’s where the PTU comes in, helping left power the right, or right power the left. Since it is activated only when the pressure falls below a certain level, the PTU cycles on and off, on and off, on and off. Due to pressure fluctuations, the noise will sometimes continue even after both engines are up and running. It also does a self-test when the starboard engine is started, so you’ll hear it then as well. Some Boeing aircraft also employ a PTU, but the operation is slightly different and it doesn’t bark like a dog.
I have been on spirit airlines from LAX (Los Angeles) to Chicago O'Hare and it had the weird sound too, don't worry about the sound if you go on spirit, it happens often and its normal.
+Captain Overlord Omg it doesnt matter that its Spirit Airlines its the PTU hydraulic system wich compensate the hydraulic differences between the two hydraulic parts of the aircraft..its typic for the a320 familiy...doesnt matter what airline.
I think that we can hear the PTU during taxiing because the aircraft taxi on a single engine and the pilot must be switch on the yellow hydraulic system pump.
+Nathan Vermeulen yes one engine is on but the PTU is making that noise because it is failing then restarting then failing again, this is only because one engine is on but the PTU has to have to engine on
In aviation, a power transfer unit(PTU) is a device that transfershydraulic power from one of an aircraft's hydraulic systems to another in the event that second system has failed or been turned off.[1] Modern airliners have separate, independent hydraulic systems powered by engine-driven pumps. The PTU is used when, for example, there is right hydraulic system pressure but no left hydraulic system pressure. The PTU transfers hydraulic power from the right hydraulic system to the left hydraulic system; there is no intermixing of hydraulic fluidbetween the left and right hydraulic systems during PTU operation. The PTU is able to operate the hydraulic motor generator during all phases of flight. It cycles on whenever an engine is started, and may repeatedly cycle on and off whenever pressure in one system drops below a certain point. While it would engage in the event of a failure, in day-to-day operations it is commonly used during taxiing when one engine is shut down to conserve fuel. The PTU on the Airbus A320 family of aircraft makes a distinctive noise resembling a barking dog, and is quite audible from inside the cabin. Passengers on board A320-family aircraft are therefore very familiar with the sound of the PTU, but few know what it is
PTU is often applied when planes taxi with only one engine turned od (fuel saving reasons), that's why in this video we can hear the other engine starting at 6:03
I’ve flown spirit many times! It always makes that noise. You mostly hear it when your closer to the engines or before them. But if your after then you usually don’t hear it. And I’ve flown the white plane which did it but the yellow plane didn’t for some reason.
Its the PTU trying to equalize the pressure from the yellow hydraulic system to the green. When the hydraulic pump on engine 1 is started, the PTU is no longer forced to compensate the loss of pressure
MTVlogs It Does It Only On Low Cost Airlines Like Jetstar etc. But If It Is A High Cost Airlines Like Thai Airways It Doesnt Do It I Dont Freak Out When I Hear It Anyways
The Premium Gamer So untrue. That's called a PTU. It helps equalize the flow of hydraulics within the airplane. It is specific to Airbus (definitely with their narrowbodies, unsure about their widebodies)
PremiumGamerTV // PGTV Hahaha, are you implying that depending on whether the airline is high or low cost Airbus delivers different types of a320s with varying specs? It's the PTU system, all of the A320 family feature it. Depending on reservoir differences for the hydrualic levels the PTU may need to transfer pressure so in some cases you won't hear it very much and in other cases it will be very loud depending on the pressure demand. The most you would ever hear it is during single engine taxi operations because the pressure would constantly need to be transferred between reservoirs unless certain pumps are utilised (Y electrical for example) or other parts of the system logic are taken advantage of.
Pretty bad that the flight attendant can't remember the name of one of her co-workers or the type of aircraft she is on. She 1st said A319 and then corrected herself.
There is nothing wrong with this plane. Green system has its EDP running from Engine 1 and just before the flaps extend the EMDP for Yellow system comes on. You can hear just before the PTU intensifies the Yellow EMDP shut down. I think usually on a one engine taxi the PTU is disabled but in this case it must be on and therefore is constantly running because EMDPs are less powerful than EDPs.
The plane has 3 hydraulic systems. Ones driven by the 2 engines and an electrically powered one. When there is not enough pressure, the barking sound (Power Transfer Unit) runs to add pressure to the weaker electrical system.
jeff darnell it's not an issue. It's a procedure where the left and right hydraulic liquids are uneven, and the sound comes from balancing, standard on all a320-family planes (brutally simplified for the sake of humanity)
OMG, the flight attendand sounds very unprofessional. It's like she's out for a coffee "meh this plane here? I don't care, let's just get through this day". I've mostly flown on lufthansa regional flights, but they're very very professional and serious.
+Neal Ochoa they only say that so if there was an emergency on take off they can see out the windows easily this is also the same reason as to not have the blinds down
Neal Ochoa Not reall. it is natural at as stated by Julio Romeresto * There is nothing wrong with this plane. Green system has its EDP running from Engine 1 and just before the flaps extend the EMDP for Yellow system comes on. You can hear just before the PTU intensifies the Yellow EMDP shut down. I think usually on a one engine taxi the PTU is disabled but in this case it must be on and therefore is constantly running because EMDPs are less powerful than EDPs.*
+Neal Ochoa last time i heard that sound on a spirit airline flight it was from fort lauderdale to the bahamas i think . And the engine had shut off in mid air. The captain got it started thought.
It’s common to hear a loud, repetitive whirring sound emanating from the floorboards of Airbus planes. Sometimes it’s a high-pitched whine; other times it’s a stilted WOOF, WOOF, WOOF, like the noise a very agitated dog might make.
This pertains to twin-engine Airbus models: the A320 series (includes the subvariants A319 and A321) and the larger A330. In the United States, the largest operators of these types are Delta, United, JetBlue, and US Airways. Almost every frequent flyer has encountered this sound at one time or another. Crews rarely make efforts to explain it, leaving passengers befuddled and sometimes worried. Because the noise is akin to a motor repeatedly trying-and failing-to start, there’s often the assumption that something is malfunctioning.
What you hear is a device called the power transfer unit, or PTU, which is designed to ensure adequate hydraulic pressures during single-engine operations. To conserve fuel, it’s fairly routine for two-engine planes to taxi with an engine shut down. Each engine normally pressurizes its own hydraulic system, but with a motor not running, that leaves one system without a power source. That’s where the PTU comes in, helping left power the right, or right power the left. Since it is activated only when the pressure falls below a certain level, the PTU cycles on and off, on and off, on and off. Due to pressure fluctuations, the noise will sometimes continue even after both engines are up and running. It also does a self-test when the starboard engine is started, so you’ll hear it then as well. Some Boeing aircraft also employ a PTU, but the operation is slightly different and it doesn’t bark like a dog.
Oh I thought it was them locking the doors.
Going on vacation on Spirit tonight! I can say it's not that fancy but it's adorable and totally worth it.
I have been on spirit airlines from LAX (Los Angeles) to Chicago O'Hare and it had the weird sound too, don't worry about the sound if you go on spirit, it happens often and its normal.
For some reason every time I go on a spirit airlines plane with sharklets, I never hear the barking sound.
+Captain Overlord Omg it doesnt matter that its Spirit Airlines its the PTU hydraulic system wich compensate the hydraulic differences between the two hydraulic parts of the aircraft..its typic for the a320 familiy...doesnt matter what airline.
This is one of the best videos I think.
What a lovely day it is, above the clouds!
I think that we can hear the PTU during taxiing because the aircraft taxi on a single engine and the pilot must be switch on the yellow hydraulic system pump.
+Nathan Vermeulen yes one engine is on but the PTU is making that noise because it is failing then restarting then failing again, this is only because one engine is on but the PTU has to have to engine on
In aviation, a power transfer unit(PTU) is a device that transfershydraulic power from one of an aircraft's hydraulic systems to another in the event that second system has failed or been turned off.[1]
Modern airliners have separate, independent hydraulic systems powered by engine-driven pumps. The PTU is used when, for example, there is right hydraulic system pressure but no left hydraulic system pressure. The PTU transfers hydraulic power from the right hydraulic system to the left hydraulic system; there is no intermixing of hydraulic fluidbetween the left and right hydraulic systems during PTU operation.
The PTU is able to operate the hydraulic motor generator during all phases of flight. It cycles on whenever an engine is started, and may repeatedly cycle on and off whenever pressure in one system drops below a certain point. While it would engage in the event of a failure, in day-to-day operations it is commonly used during taxiing when one engine is shut down to conserve fuel.
The PTU on the Airbus A320 family of aircraft makes a distinctive noise resembling a barking dog, and is quite audible from inside the cabin. Passengers on board A320-family aircraft are therefore very familiar with the sound of the PTU, but few know what it is
PTU is often applied when planes taxi with only one engine turned od (fuel saving reasons), that's why in this video we can hear the other engine starting at 6:03
PTU starts at 3:05
I’ve flown spirit many times! It always makes that noise. You mostly hear it when your closer to the engines or before them. But if your after then you usually don’t hear it. And I’ve flown the white plane which did it but the yellow plane didn’t for some reason.
PTU is for the hydraulic system. Also, spirit is having a one engine taxi proceedure.
Sounds like that plane needs oil, nice video
The plane flies away @16:52
takes off
Is single engine taxi practiced based on airlines that choose to use it?
Well I hope i don't have any issues with them but I'll end up complaining anyway when I head to Boston in a month
Lol that noise wasn't a dog I've flown in spirit before and it always makes that annoying noise
Its the PTU, all airbus models have it
Its the PTU trying to equalize the pressure from the yellow hydraulic system to the green. When the hydraulic pump on engine 1 is started, the PTU is no longer forced to compensate the loss of pressure
Talynn Nicole one time I’ve been on an Airbus I didn’t hear it LOLOLOL
@@certifiedwebmer this noise on particular is only heard on the A320 series
@@certifiedwebmer and you could've been seated further from the engine
Damn it Airbus! Are passengers informed that there will be a normal "barking" noise? Because if they don't I bet some passengers would freak out.
MTVlogs It Does It Only On Low Cost Airlines Like Jetstar etc. But If It Is A High Cost Airlines Like Thai Airways It Doesnt Do It I Dont Freak Out When I Hear It Anyways
The Premium Gamer So untrue. That's called a PTU. It helps equalize the flow of hydraulics within the airplane. It is specific to Airbus (definitely with their narrowbodies, unsure about their widebodies)
PremiumGamerTV // PGTV Hahaha, are you implying that depending on whether the airline is high or low cost Airbus delivers different types of a320s with varying specs? It's the PTU system, all of the A320 family feature it. Depending on reservoir differences for the hydrualic levels the PTU may need to transfer pressure so in some cases you won't hear it very much and in other cases it will be very loud depending on the pressure demand. The most you would ever hear it is during single engine taxi operations because the pressure would constantly need to be transferred between reservoirs unless certain pumps are utilised (Y electrical for example) or other parts of the system logic are taken advantage of.
Only the aircraft with IAE engines have the PTU (power transfer unit) Most of the CFM engined aircraft do not have the PTU.
??? All a320s have PTU's, engines dont matter.
I was taking Spirit airlines from Fort Lauderdale too
Airbus a320s do make that noise sometimes i dont know why some people think Boeing 737s are louder
All you have to do is google strange barking sound from A320 and you find out what it is. That’s how most non aviation people came to their answers.
The PTU sounds like a broken german shepard
XD
Pretty bad that the flight attendant can't remember the name of one of her co-workers or the type of aircraft she is on. She 1st said A319 and then corrected herself.
There is nothing wrong with this plane. Green system has its EDP running from Engine 1 and just before the flaps extend the EMDP for Yellow system comes on. You can hear just before the PTU intensifies the Yellow EMDP shut down. I think usually on a one engine taxi the PTU is disabled but in this case it must be on and therefore is constantly running because EMDPs are less powerful than EDPs.
Did not understand a thing 😂😂😂
The plane has 3 hydraulic systems. Ones driven by the 2 engines and an electrically powered one. When there is not enough pressure, the barking sound (Power Transfer Unit) runs to add pressure to the weaker electrical system.
I just flew today and our Airbus A319 was also doing this, everyone was kinda looking around like "wtf?".
jeff darnell it's not an issue. It's a procedure where the left and right hydraulic liquids are uneven, and the sound comes from balancing, standard on all a320-family planes (brutally simplified for the sake of humanity)
Also the reason why the engine made weird sounds (PTU) is because they were taxiing with one engine to save fuel.
The pop can airplane makes the same noise
To hell with the flight attendant, you are the customer and these wanna be prison guards seem to forget that.
That;s just really annoying for passengers - poor souls
i love it
That sound PTU seems to happen on all A320 or A321s
that's true
That annoying sound like wtf 😒
woof woof woof woof woof woof
OMG, the flight attendand sounds very unprofessional. It's like she's out for a coffee "meh this plane here? I don't care, let's just get through this day". I've mostly flown on lufthansa regional flights, but they're very very professional and serious.
Well it's Spirit, it seems ever five years the have to rebrand.
No she doesnt if u fly southepwest it's exactly the same and southwest is much more professional
SergeantGhost she just sounded bored.
SergeantGhost well this is spirit
what camera did you use
i was thinking of using my gopro
+Neal Ochoa they only say that so if there was an emergency on take off they can see out the windows easily this is also the same reason as to not have the blinds down
Lol woof woof woof, does this plane have a dog in it.? Just kidding!!!!
Jesus...
wtf is that noise????
airplane
sounds like the APU was having trouble getting started
PTU
what are you talking?
Go home team FLL!
ti
Probably the longest barking I've ever heard...
Lol that sound waznt a dog
It's a mechanical issue not the airline
Neal Ochoa
Not reall. it is natural at as stated by Julio Romeresto *
There is nothing wrong with this plane. Green system has its EDP running from Engine 1 and just before the flaps extend the EMDP for Yellow system comes on. You can hear just before the PTU intensifies the Yellow EMDP shut down. I think usually on a one engine taxi the PTU is disabled but in this case it must be on and therefore is constantly running because EMDPs are less powerful than EDPs.*
+Neal Ochoa last time i heard that sound on a spirit airline flight it was from fort lauderdale to the bahamas i think . And the engine had shut off in mid air. The captain got it started thought.
+Slappingcreeper 121 Good guess, but wrong
🛫🛩✈️🛬🚝pta
🚃🚃🚃PTA