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Airbus sound question

great cornholio

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I was commuting in on an Airbus tonight and the pax next to me asked me what a sound was. I told them I had no idea what it was since I have no idea what it is. Anyways I hear it on the Airbus pretty often seems to happen right before or during push and then again pulling into or right after blocking into the gate. Best way to describe the sound is that it sounds like a midget with a hacksaw under the floor. Seems to be louder over the wings. Anyways have been asked a few times over the years and have even wondered myself, but tonight was the first night I was bored enough to ask about it here.
 

kf4amu

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I was wondering the same thing. Sounds like a very loud pump turning on and off randomly.
 

ImbracableCrunk

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I always think of a barking dog. RUH Ruh ruh. RUH Ruh ruh.

Where's Click & Clack when we need em?
 

UALjan15

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Hydraulic power transfer unit (PTU) runs during single engine ops to keep dead side hydraulic pressure up. It can be turned off, but I don't know how many airlines do so in their procedures.
 

i fly boxes

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I always tell passengers they are sawing of the wing cause its due for replacement. Thats what it sounds like
 

Volasl

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The PTU is a reversible motor-pump located between the Green and Yellow hydraulic systems. It enables the green system to pressurize the yellow system, and vice versa, without fluid transfer. The PTU is automatically activated when the differential pump pressure output between the green and yellow systems exceeds a predetermined value (500 PSI). On the ground, when the engines are not running, the PTU enables the yellow system electric pump to pressurize the green system. Operation of the PTU is displayed on the ECAM page and also indicated via an ECAM memo.

PTU operation is inhibited when the:

  • <Nosewheel steering in the towing position
  • First engine is being started (PTU operation is automatically tested during second engine start)
  • Cargo doors are operated and for 40 seconds after the end of cargo door operation
  • Parking brake is ON and only one ENG MASTER switch is ON
  • PTU pb is OFF
 
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SpauldingSmails

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It's a fat lady in corduroy pants walking around.
 

freeflyer14

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Funny this thread should come up, I was deadheading on a UA bus the other day, and this sound started. These passengers around me (obviously not the most well seasoned travelers) started to freak out. I then got to listen to a 15 minute dissertation about how this airplane was a piece of junk, was dangerous, old (this was actually a newer looking A319), too loud, unsafe, etc etc.
 

great cornholio

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The PTU is a reversible motor-pump located between the Green and Yellow hydraulic systems. It enables the green system to pressurize the yellow system, and vice versa, without fluid transfer. The PTU is automatically activated when the differential pump pressure output between the green and yellow systems exceeds a predetermined value (500 PSI). On the ground, when the engines are not running, the PTU enables the yellow system electric pump to pressurize the green system. Operation of the PTU is displayed on the ECAM page and also indicated via an ECAM memo.

PTU operation is inhibited when the:
  • <Nosewheel steering in the towing position
  • First engine is being started (PTU operation is automatically tested during second engine start)
  • Cargo doors are operated and for 40 seconds after the end of cargo door operation
  • Parking brake is ON and only one ENG MASTER switch is ON
  • PTU pb is OFF


Thanks for the info. I always thought it was something related to the HYD sys.
 

great cornholio

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NEDude

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If you turn on the yellow electric pump you never have that noise..

I am amazed at how few airlines seem to not turn it on during single engine taxi. I was riding in the back of a United A319 a few weeks ago during a long taxi in ORD and the PTU ran for 40 minutes before they started the other engine.
 
Last edited:

flyn96

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Heard a pax say how it sounded like a barking dog down in cargo and how the airline was so bad that they couldn't even treat a dog with respect. Pretty funny stuff.
 

Bringupthebird

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I am amazed at how few airlines seem to not turn it on during single engine taxi. I was riding in the back of a United A319 a few weeks ago during a long taxi in ORD and the PTU ran for 40 minutes before they started the other engine.
If you're taxiing on No. 2 then running the electric pump doesn't do any good (eng2 is driving the yellow pump anyhow). If you're taxiing on No.1, you have the yellow electric pump operating in the unlikely event you shuck the green pump. Moral of the story: SE taxi on eng 1 only (if you can ). Also the electric pump can overheat.


I had a passenger get off the airplane saying "I thought you'd never git that motor started with that dead batt'ry. She just cranked and cranked and cranked."
 
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