Engine Startup and PTU sound (Only sound)
Why Aviation Stack Exchange recommends it
Aviation Stack Exchange users link it as a reference recording of the A320's "barking dog" PTU sound when explaining mystery noises passengers hear on Airbus aircraft.
Recommended by 0 people across 0 different months, 2014 to 2017.
What it is
A 1.5-minute audio-only recording made on a Lufthansa Airbus A320 flight from Manchester to Frankfurt. It captures the engine startup, the flaps extending, and the distinctive PTU (Power Transfer Unit) noise.
What people said
Cites ravingraven · 2014-04 · Aviation Stack Exchange · on “What noises can you hear as a passenger?”
An interesting noise you can hear is the sound of the PTU (Power Transfer Unit) during the A320 startup. It sounds like a cross between a dog barking and someone dragging a wet finger across glass. [this video] What happens is that the PTU is transfering pressure from one hydraulics system to the other to equalize them. Since the pressure is not always unequal between the hydraulics systems, this is not audible during every startup.
Cites Ludovic C. · 2014-05 · Aviation Stack Exchange · on “What is this sound from Airbus aircraft before take off?”
It's definitely the PTU as you can hear on this video [LINK] or this other one [this video] . And I also do remember hearing this sound at the point just before the acceleration for take off.
Cites user3780731 · 2015-01 · Aviation Stack Exchange · on “What is the scratching sound produced by aircraft on the ground (taxi-in/taxi-out)?”
Yes indeed! I just found the sound in this video I found on the other post. [this video] It is the PTU, I needed to know. Thank you very much. @SentryRaven
Cites PerlDuck · 2017-01 · Aviation Stack Exchange · on “Taxiing with one engine: Is engine #1 always used or do they switch?”
I recently travelled with an A320 and an A321 from FRA (Frankfurt) to TXL (Berlin) and back again. On this and on previous flights I already noticed a whining sound, much louder than other sounds, while we were still at the gate or soon after leaving the gate and starting taxiing. I cannot remember exactly. My research showed that this was the PTU's sound (aka “barking dog” [this video] ), typical for an A320 and its sisters. One of my references was this post [LINK] . The author said: [The PTU can be heard] At the gate, especially if we taxi in on one engine. During the taxi, the left engine is running and pressurizing the green system. This led me to this question: When taxiing with one only en
Cites PerlDuck · 2017-03 · Aviation Stack Exchange · on “What could cause a noise like a hammer on an A320 in flight?”
@JustSid Right. That's what the PTU is designed for (as I learned here :-)). But wouldn't it make the typical “barking dog” [this video] sound the A320 is famous for?