MYSTERIOUS BARKING SOUND on AIRBUS? All about the PTU explained by "Captain"Joe

  • Published on Mar 2, 2017
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    Dear Friends and Followers!
    What is that barking sound coming from below the cabin floor as soon as we reach the gate position? Have you ever wondered what is going on in the cargo compartment where this very strange noise is coming from. Many people refer to this as the "Airbus Barking Dog Sound".
    This strange barking sound emits from the PTU, the Power Transfer Unit which is a substantial part of the Airbus hydraulic system. I explain in further detail when the PTU is being operated and it´s purpose.
    Now the Airbus A320 hydraulics consist of three independent system, named in colours, green, blue and yellow and one of their highest priorities is to pressure the actuators to move the flight controls.
    the green system is powered by an engine driven hydraulic pump, engine number 1, so in flying direction the engine to your left hand side and the yellow system is powered by engine number 2 but can also be powered by an electric backup pump.
    The blue system is powered by an electric pump only but isn´t associated with the PTU. It does, however, have its own unique backup mechanism, the Ram Air Turbine, but that´s a whole another video.
    So imagine the PTU as a reversible motor pump located between the green and yellow systems. Hydraulic fluid from either system can drive the pump to pressurise the other hydraulic system. But the fluids only drive the pump so the remain isolated from each other, meaning they don´t mix
    Each hydraulic system normally operates at 3000psi and if the difference between the green and yellow system exceeds 500psi, the system energises the PTU to pressurise the low system. In other words, the green or yellow hydraulic pump has failed and is being pressurised from the other system through the PTU.
    What the video for more information :)
    Thanks for your time and see you next thursday. Make sure to stop by my Instagram account at "flywithcaptainjoe" and subscribe my channel for more upcoming video.
    All the best, Your "Captain" Joe
    ONE MISTAKE IN VIDEO, you preferably start engine number 2 first and then engine number 1, in that sequence! Sorry about that !
  • Science & TechnologyScience & Technology

Comments • 1 527

  • Amit Parmar
    Amit Parmar 4 days ago

    No dogs were hurt during takeoff

  • Haziel Soberal
    Haziel Soberal 5 days ago +1


  • п
    п 14 days ago +2

    Sounds more like a window-cleaning noise to me

  • Mas Rifqi
    Mas Rifqi 17 days ago

    I adore his laugh

  • Paulie Walnuts
    Paulie Walnuts 19 days ago

    Serious question - I’d love to know more about your accent when speaking English. The German intonation sounds so soft and not like any other German I’ve heard speaking English!

  • Airplaneair Gameplays
    Airplaneair Gameplays 20 days ago

    that sound keeps annoying me whenever I'm on that a320 because it scares me

  • Mico Carlo Adrian Ruiz

    Cebu Pacific A320 is on the gate
    Passengers: wha??
    A320: *does it again*
    Passenger: is there a freaking dog here?

  • Jesus Gutierrez
    Jesus Gutierrez 28 days ago

    Captain Joe what is that sound when the landing gear goes up/down? Is it the PTU?

  • Charles Magrin
    Charles Magrin Month ago

    "during engine start, engine 2 is not yet running" aren't you supposed yo start engine 2 first on an Airbus?


    I heard this sound for the first time on a JetBlue flight from LBG to ATX for the entire flight. It that normal??

  • Panzerkampfwagen VI Ausf Tiger I E

    I heard it on my flight

  • imaad shaikh
    imaad shaikh Month ago


  • Tatyana I
    Tatyana I Month ago

    that sucked

  • katelilymilly
    katelilymilly Month ago

    Yep definitely a dog 🐶 😈

  • Komrade BigTex sucks

    Yeah... I've actually never been on am airbus, only Boeing and Bombardier planes. This is depute me having flown more than 50 times in just the last 10 years.

  • Lee Zinke
    Lee Zinke Month ago

    Is there a dog on the plane? lol

  • Ray Espinoza
    Ray Espinoza Month ago

    Ok thats a good one cap joe always have a safe fligth God bless airlines

  • Matthew Lo
    Matthew Lo Month ago

    I thought this was something related with the Dog of Wisdom video...

  • Franchisemae Castillo

    I actually thought that the cabin doors are closing,,hmm

  • NebNalon
    NebNalon Month ago

    We had this on a flight last week. They were doing pre flight startup etc and the noise went on longer than expected. They did this numerous times then declared a fault and called an engineer. 2.5 hours later we took on more fuel and clear to takeoff. Halfway into climbing the barking started, I panicked as I thought this only happened on the ground? Ironically on approach on the return leg using a different plane, the barking started when coming into land - is this usual? I've never heard this in the air before?! New BA procedures?

  • Daniel Haslam
    Daniel Haslam Month ago

    Terrain Terrain. Woof Woof! Pull Up! Woof Woof! Pull Up! Woof Woof! Pull up!

  • Ethan H
    Ethan H Month ago

    Ooh! I got a Embraer E2 ad!

  • Senor eggnogs
    Senor eggnogs Month ago

    he err....he did the german three

  • list the gamer
    list the gamer Month ago

    Ive been in a a320 a321 a319 A319

  • Taylor Duskwalker
    Taylor Duskwalker Month ago

    My little paranoid ass used to think some asshole terrorist tried to cut a wing off using a wood saw. Thank you for the clarification.

  • RFI-Crypto Lab
    RFI-Crypto Lab Month ago

    My mom who hasn't flown in decades thought it was a dog.
    Everytime we are taxiing on an A320 I like to listen to people's comments when that pump kicks on.
    Some are curious and a few are always slightly alarmed. If you aren't familiar it does sound like some motor is trying to start but cant.

  • Znek
    Znek Month ago

    I heard this on a a319 from Brussels airlines

  • Major League Gamer
    Major League Gamer Month ago

    For me it sounds like someone is rubbing a towel on a squeaky clean window

  • sosichan
    sosichan Month ago

    I always wondered about the barking!!! Thanks for clearing this up for me 😁

  • Yohannes Sulistyo
    Yohannes Sulistyo Month ago

    It can be heard as well during: landing gear retracting or deploying, or when wheel brakes are applied. On older planes, during extreme turbulence and when the plane is constantly trimming. Then in one of my experience, when the flaps is extended. The scariest part is when I heard it continuously barking during landing gear extension (we were at approach), but then there was no loud wind noises to indicate the gear doors opening and a "thump", I was like "OMG, landing gear fail". But then, 5 seconds later I heard that comforting loud wind noises from below the floor. At this point I'm assuming that anything that requires hydraulic power, will trigger the noise. The older the system, the louder and the laggier the noise and effects.
    You can feel the "lag" too, they bark first and then the action commences. In Airbus A330, the PTU noise is different, but also give the same effect, you will heard a gas nozzle and a thump, then you'll feel the brakes decelerating the plane. Sitting in the middle section (overwing) is the best place if you want to hear these noises. But man, I feel that Airbus needs to insulate their planes better from all sorts of distracting mechanical noises.

  • K9-1000
    K9-1000 Month ago

    LOL I always thought it was the walking tunnels being disconnected.

  • man of the woods
    man of the woods Month ago

    Lol i never thought of it as a dog. I just panic for my life thinking one of the engines dont start 😅

  • Murilo C. de Souza
    Murilo C. de Souza Month ago

    I just thought it was a saw, simple.

  • Dave Hagen
    Dave Hagen Month ago

    I flown with Aer Lingus A320 and I didn't hear that sound

  • Fernan Aquino
    Fernan Aquino Month ago

    Haha. That sound. I hear that before the plane backs up and go taxing. Scoot airbus a320

  • wash beezy
    wash beezy Month ago

    Ok, before watching this video I think I know what that sound is. Or at least I have a good idea. I'll let you know if I was right after I watch the video. I'll be honest.

    • wash beezy
      wash beezy Month ago

      Yup!! I was waaaaaay off. To be honest though I never associated that noise as a barking dog though.

  • Νικόλαος Βόρδος

    So should I be worried that I hear it during descending?

  • Nicholas Hartzler
    Nicholas Hartzler Month ago

    So what does Boeing do different?

  • SkyCharger001
    SkyCharger001 Month ago

    AFAIK in the rare case that nose-steering (or even worse, all internal taxiing) is lost, the nose-gear assembly must be able to take the stresses of being towed by a pullback as well as being pushed. (even if only long enough to be towed out of the runway.)

  • Nel Alonto
    Nel Alonto Month ago

    One time after pushback a pax reported to the purser he heard a strange barking noise... the purser reported to the capt.. they decided to go back to the gate.. a needless delay but we had a good laugh..

  • Leandro Araujo
    Leandro Araujo Month ago

    Superb explanation!! Thank you, captain!

  • Ryan Larrieux
    Ryan Larrieux Month ago

    I learn from you

  • Fa Api
    Fa Api Month ago +1

    Hey joe
    How are you?
    Once I saw smoke in a cabin while take off in summer I was panicked but my husband relaxed me .What was that?

  • Spy Agency
    Spy Agency 2 months ago

    By the way I’ve traveled in a A320 and I never heard it but now I know Incase I’ve heard it

  • RRareGaming
    RRareGaming 2 months ago

    I didn't here it

  • Borislav Baychev
    Borislav Baychev 2 months ago

    Joe.. with all my respect.. although.. I'm pretty sure there is a dog inside each A320. So kinly explain in you next video how exactly the dog works :D

    DAVEMAN YT 2 months ago

    I heard that sound at A380 😊

  • Sai Praveen
    Sai Praveen 2 months ago

    Love from India - Wish I could board a plane when you are a First Officer in the same plane :-

  • Carly Beatz
    Carly Beatz 2 months ago

    Captain Joe, your videos are bloody amazing! Sitting here for hours watching these hahah :-D

  • Ozan
    Ozan 2 months ago +3

    Damn even the hydraulics are RGB! xD

  • Diptangshu Santra
    Diptangshu Santra 2 months ago

    You really took away one of my fears, that may be one of engines has got some fault :D
    Thanks a lot !

    RYAN_ STARALLIANCE 2 months ago

    Does this apply for Airbus 318/19/20/21's with both CFM56 and or IAE-V2500's? I've heard this sound on Airbus's with both types of engines

  • Jason B
    Jason B 2 months ago

    Too put more simple.. The airplane manufacturer got CHEAP... They don't have to hear it as a passenger soooo "let's not reduce the noise". Oh yea the those "college degree engineers" aren't allowed to design a pressure regulator etc. Its just more design flaws to save a buck and little weight. Oh yea speaking Engineering those guys want lower fuel and no additional weight? Take every gear and bearing in the engine and drive units. Go get it coated. The coating is extremely thin and practically indestructible (it's made for racing cars).
    Oh yea I guess I dumb because I don't have a "degree" 😂. Well I say without certainty nearly every Engineer working for a firm is merely a robot..🤖 (must follow commands) from sales and marketing department.🤑
    Well besides my rant I enjoyed the explanation of the below deck barking dog.

  • AMR Sports
    AMR Sports 2 months ago

    I was wondering about this.. Thank you sir

  • Jan Raid
    Jan Raid 2 months ago

    I heard that noise while descending

  • Daniel Peixoto Martins
    Daniel Peixoto Martins 2 months ago

    Captain Joe and when the barking sound is really a barking dog? Last time I flew to Frankfurt on an A321 there was actually a real dog barking from boarding till we were unbordaded. It never ever stopped barking!

  • DMSDrummer
    DMSDrummer 2 months ago

    Every time I’m on an A320.... I finally know

  • sean rollins
    sean rollins 2 months ago

    Gotta love 1987 technology 😒 I'm surprised it doesn't start playing Men Without Hats or Depeche Mode.

  • VocaloidI ZumeK
    VocaloidI ZumeK 2 months ago

    Hmm, I only hear that sound after we start getting ready to leave the gate. And I've never thought of it as a dog barking either. Ahah

  • Mark Fosseth
    Mark Fosseth 2 months ago

    And if there was a real barking dog in the cargo ? 😁

  • Soham Bandyopadhyay
    Soham Bandyopadhyay 2 months ago

    So captain joe is German....😉😊

  • David Crossey
    David Crossey 2 months ago

    Finally understand what this noise is! Thanks Captain Joe!!

  • [Error]
    [Error] 2 months ago +2

    I heard this on Airbus A321-200

  • LaSer St
    LaSer St 2 months ago

    Hi Captian, don't know where should I ask you a question but talking about the sound of Airbus, I found some of 330s making sounds like rudder smashed to max. position (chi-dong) when taixing. Could u explain what is this? Thanks a lot.

  • Kenroi Ondap
    Kenroi Ondap 2 months ago

    I heard this duribg taxi, during takeoff It sounds weird:(

  • Nika Adeishvili
    Nika Adeishvili 2 months ago

    HAHA funny :D

  • vince ha
    vince ha 2 months ago

    I love your videos Captain Joe

  • Thomas Gaming
    Thomas Gaming 2 months ago

    I’ve herd this before but it sounds like a saw to me

  • Pak Aviator
    Pak Aviator 2 months ago

    Nice video very good for extra Knowledge. I fly planes to but haven’t reached to the Airbus A380 yet 😞

  • Robert Rogers
    Robert Rogers 2 months ago

    ive never heard that sound before

  • ken vuong
    ken vuong 2 months ago

    What was that propeller under the plane?

    REAL LOUISE 2 months ago +1

    Can i ask a question.. whats inside a tires of an airplane?

  • Devansh Tiwari
    Devansh Tiwari 2 months ago

    What is a yaw damper?

  • Alex zander
    Alex zander 2 months ago

    The dog is a pet in a crate in the hold

  • chels L
    chels L 2 months ago

    I thought it was an actual dog...

  • Daniel Price
    Daniel Price 2 months ago

    E A S Y J E T

  • Sidath Buddika
    Sidath Buddika 2 months ago

    Are you pilot or engineer .you are best teacher.i like you

  • R R
    R R 2 months ago

    I heard it in mid flight

  • Max Smale
    Max Smale 3 months ago +1

    Can planes fly backwards???

    • erikk77
      erikk77 Month ago +1

      Only above 500,000 feet.

    • Moishy Ok
      Moishy Ok 3 months ago +1

      What a stupid question 😂, you made my day

  • Lalit Dhingra
    Lalit Dhingra 3 months ago

    In one of my hopping flights on Indigo (India), I heard this noise on the ground, post take off, preparing to land and post landing. It was scary hearing it mid air. Was that some kind of failure?

  • yo soy myself
    yo soy myself 3 months ago +1

    *Sometimes everything you talk goes all above my head*

  • Dantm's Guest
    Dantm's Guest 3 months ago


  • Henrik Roback
    Henrik Roback 3 months ago

    Thanks I have always wondered. Once I heard this sound directly after take off, is this normal though!?

  • Jaimichu9
    Jaimichu9 3 months ago

    Hi captain! Dont know if you will be still active on this year old video but Ill still throw in my question anyways :). So you mentioned that while one engine taxi procedures the yellow electric pump is turned on to pressure the system. My question is why turn the electric pump on when you can just leave the ptu pressurize the systems? Thanks in advanced.

  • CX001
    CX001 3 months ago

    I heard it yesterday on an a319

  • Nitish Kasavaraj
    Nitish Kasavaraj 3 months ago

    Greetings Joe, It did solve one of my mysteries as I used to think it was a problem with the Engine. However I don't find this sound in most of the Boeing aircrafts. Could you explain what's different there? Thank you Captain

  • EstSailor
    EstSailor 3 months ago

    I thought first time that it was immigrant cutting himself out

  • AnnasStorybox
    AnnasStorybox 3 months ago

    The sound reminds me of the chain chomps in Super Mario...

  • The Mining Nightcraft Studio !!!

    The sound is a sticky vaulve im guessing

  • Jimmy Fork
    Jimmy Fork 3 months ago

    It sounds alot less like a dog and more like a long squeak imo

  • Infinite Tuber
    Infinite Tuber 4 months ago

    What is that pointy thing at the edge of the flaps? (my dad ask me that question and I have no idea what is that for)

  • Marco Belicchi
    Marco Belicchi 4 months ago

    Just heard it a few days ago on a BA A321, it's really loud!

  • Jimm Playz134
    Jimm Playz134 4 months ago

    You need infinite subs Captain Joe xD.

  • jacksepticeye sean
    jacksepticeye sean 4 months ago

    Subscribe to menture pilot

  • Jane Grant
    Jane Grant 4 months ago

    I didn't understand a word I'm afraid but I suppose it was vaguely reassuring.... but have heard that noise after take off on a A319. Does that mean only one engine was working?

  • sharaj naidu
    sharaj naidu 4 months ago

    I'm about to finish my engineering degree(2019) and I want to start getting my pilot license to be able to fly.I've always wanted to be a pilot, but family pressure really pushed me to engineering(no hate :)) so what do I do now?

  • Chet Patel
    Chet Patel 4 months ago

    and i thought it was the flaps

  • Chet Patel
    Chet Patel 4 months ago

    LOL! = Laugh Out Loud

  • FNaNothing
    FNaNothing 4 months ago

    They kinda sound like the windshield wipers

  • MidnightVisions
    MidnightVisions 4 months ago

    The PTU sounds like a sick cow during maintenance of the aircraft and flap lowering.