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A320 PTU Question  
User currently offlineHorizonGirl From Canada, joined Mar 2005, 807 posts, RR: 15
Posted (9 years 6 months 3 weeks 4 days 19 hours ago) and read 14295 times:

Hello everyone!

I am sorry if this topic has been previously discussed,
but I did a forum search and nothing turned up. I tried asking this
in an other thread, but it was soon after locked.
My question is why dose the A320 PTU "Bark?"
I know how it works, what it is, and that some people get
quite nervous when they hear it.
But what is it exactly that makes it make those impossible to ignore barks?  Yeah sure
Thank you for any help that you may be able to provide.

Devon


Flying high on the Wings of the Great Northwest!
22 replies: All unread, jump to last
 
User currently offlineGOCAPS16 From Japan, joined Jan 2000, 4347 posts, RR: 21
Reply 1, posted (9 years 6 months 3 weeks 4 days 19 hours ago) and read 14288 times:

A PTU is like a dog...for some reason it just barks  Smile

Kevin



SIX T'S!......TURN. TIME. TWIST. THROTTLE. TALK. TRACK.
User currently offlineHorizonGirl From Canada, joined Mar 2005, 807 posts, RR: 15
Reply 2, posted (9 years 6 months 3 weeks 3 days 22 hours ago) and read 14033 times:

LOL, They should recognize the PTU as an official breed!


Devon



Flying high on the Wings of the Great Northwest!
User currently offlineCactusTECH From , joined Dec 1969, posts, RR:
Reply 3, posted (9 years 6 months 1 week 4 days 13 hours ago) and read 13890 times:

The PTU is mechanical pump that links the yellow and the green hydraulic systems. It is energized when either system has been turned off( ex: one engine off) it produces a loud high frequency noise when it turns and produces 3000 psi hydraulic pressure for oppsosite system.

User currently offlineTroubleshooter From Germany, joined Feb 2005, 423 posts, RR: 5
Reply 4, posted (9 years 6 months 1 week 3 days 21 hours ago) and read 13844 times:

I think, the noise is produced by the fast moving (rotating) mechanical components inside the PTU. This leads to high frequency vibrations which are translated by the attached plumbing and PTU mounts.
All PTUs I know can be recognized by a loud "barking" sound. So I assume the noise is related to the PTU design and not only a A320 specific noise.



This job sucks!!! I love this job!!!
User currently offlineKlaus From Germany, joined Jul 2001, 21484 posts, RR: 53
Reply 5, posted (9 years 6 months 1 week 3 days 15 hours ago) and read 13826 times:

One forum member has once explained that Airbus explicitly wanted to have the PTU sound clearly audible to make troubleshooting on the ground easier. I don´t know if that´s exactly correct, but it might be an explanation. Newer versions are reported to be somewhat less noticeable (also from earlier threads).

User currently offlineFadec From United States of America, joined Jun 2004, 45 posts, RR: 0
Reply 6, posted (9 years 6 months 1 week 3 days 15 hours ago) and read 13826 times:

The reason it "barks" is because it switches on and off so quickly. As pressure drops it comes on just long enough to build the pressure back to 3000 psi. Once that is done it shuts off until the pressure drops again... in about 5-15 second intervals normally, depending on how good the pressure bleed down rate is on that particular aircraft.

If you lower the flaps for instance the barking will stop and you will hear the pump run continuously (which is also quite loud) until the pressure is built back up after system demand has stopped.

I believe the A320/319 is the only aircraft you can hear the PTU so distinctly during normal operations. The 757/767 ETOPS for instance, it is heard only with a system failure. I've personally only heard it during maint. test's. Most non-ETOPS aircraft don't even have a PTU.


User currently offlineUAL Bagsmasher From United States of America, joined Sep 1999, 2147 posts, RR: 10
Reply 7, posted (9 years 6 months 1 week 3 days 15 hours ago) and read 13823 times:

The BAE-146 also "barks" quite loud, at least in the hangar.

User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 68
Reply 8, posted (9 years 6 months 1 week 3 days 12 hours ago) and read 13812 times:

Quoting UAL Bagsmasher (Reply 7):
The BAE-146 also "barks" quite loud, at least in the hangar.

Ahhh, but that is because the BAe-146 is a dog.



Happiness is not seeing another trite Ste. Maarten photo all week long.
User currently onlineMD11Engineer From Azerbaijan, joined Oct 2003, 14060 posts, RR: 62
Reply 9, posted (9 years 6 months 1 week 3 days 7 hours ago) and read 13776 times:

All hydraulic pumps make noise, on engine driven pumps it is usually drowned by the engine noise, but did anybody in here ever stick his head into the "B" system compartment of a 727? You´ll need ear protection because of the racket the two electric driven pumps make. The same applies to the R/H wheel well of a MD-11.

Jan


User currently offlineHorizonGirl From Canada, joined Mar 2005, 807 posts, RR: 15
Reply 10, posted (9 years 6 months 1 week 3 days 6 hours ago) and read 13768 times:

Thank you everyone so much.
Figured it had to do with the pressure but wasn't 100% sure.
Now that I know for sure I can go back to talking at my
friends about this.
Devon



Flying high on the Wings of the Great Northwest!
User currently offlineUAL Bagsmasher From United States of America, joined Sep 1999, 2147 posts, RR: 10
Reply 11, posted (9 years 6 months 1 week 3 days 1 hour ago) and read 13727 times:

Slamclick, we actually call it the "Pig". But either way, it's an animal that will turn around and bite you in the a** as soon as you let your guard down. (From an A&P's view at least Wink)

User currently offlineGOCAPS16 From Japan, joined Jan 2000, 4347 posts, RR: 21
Reply 12, posted (9 years 6 months 1 week 3 days ago) and read 13717 times:

LOL, are your friends interested in the "barking" sound of the PTU?

Kevin



SIX T'S!......TURN. TIME. TWIST. THROTTLE. TALK. TRACK.
User currently offlineLHB727230Adv From Germany, joined Mar 2005, 255 posts, RR: 0
Reply 13, posted (9 years 6 months 1 week 2 days 21 hours ago) and read 13702 times:

I know this is a stupid question coming from me, but what exactly is a PTU and what is it used for?

Cheers,
Alex  bigthumbsup 


User currently offlineNKP S2 From United States of America, joined Dec 1999, 1714 posts, RR: 5
Reply 14, posted (9 years 6 months 1 week 2 days 14 hours ago) and read 13692 times:

Quoting LHB727230Adv (Reply 13):
I know this is a stupid question coming from me, but what exactly is a PTU and what is it used for?

Stupid? No. Lazy, maybe. Read the 3rd reply. See also other recent thread: http://www.airliners.net/discussions/tech_ops/read.main/93654/

Some good info amongst all the "fan" fluff. That and multitudinous other posts in multiple other threads discussing same.


User currently offlineLHB727230Adv From Germany, joined Mar 2005, 255 posts, RR: 0
Reply 15, posted (9 years 6 months 1 week 2 days 13 hours ago) and read 13680 times:

Thanks, NKP S2, I must have missed reply 3.  banghead 
Wierd, I never noticed the A320 barked, I've flown on it dozens of times and never heard a barking sound.

Cheers,
Alex  bigthumbsup 


User currently offlineHorizonGirl From Canada, joined Mar 2005, 807 posts, RR: 15
Reply 16, posted (9 years 6 months 1 week 2 days ago) and read 13659 times:

You would have to be sitting around the wing area in
order to hear it.

Devon



Flying high on the Wings of the Great Northwest!
User currently offlineLHB727230Adv From Germany, joined Mar 2005, 255 posts, RR: 0
Reply 17, posted (9 years 6 months 1 week 1 day 19 hours ago) and read 13653 times:

Quoting HorizonGirl (Reply 16):
You would have to be sitting around the wing area in
order to hear it.

Thanks, I'll keep that in mind for next time I fly the A320

Cheers,
Alex  bigthumbsup 


User currently offlineHorizonGirl From Canada, joined Mar 2005, 807 posts, RR: 15
Reply 18, posted (9 years 6 months 1 week 3 hours ago) and read 13603 times:

Quoting GOCAPS16 (Reply 12):
LOL, are your friends interested in the "barking" sound of the PTU?

I teach a fear of flying class, but aside from that,
I would say not. laughing 


Devon



Flying high on the Wings of the Great Northwest!
User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 19, posted (9 years 6 months 6 days 22 hours ago) and read 13586 times:

Any Audio of this "Barking" sound.On the A320 that is  Smile
regds
MEL



Think of the brighter side!
User currently offlineF-WWAI From Andorra, joined Dec 1999, 131 posts, RR: 0
Reply 20, posted (9 years 5 months 4 weeks 1 day 5 hours ago) and read 13510 times:

the PTU is there to transfer hydraulic power from Green to Yellow or from Yellow to Green hydraulic system, but without exchange of hydraulic fluid.
It's a motor/pump power reversal configuration.
While normal system pressure is 3000 psi, the Power Transfer Unit cuts in when the receiving system pressure falls below 2500 psi. If there is high consumption of hydraulic power on the receiving system, then the PTU operation is continuous.
If there is only system leakage flow, then the PTU barks coming ON and OFF. The ops is normally inhibited on ground when the parking brake is set for standard engine starting at departure. But for any single engine pushback or taxi ops the PTU will wake up.
have fun,
watch airbus,
fw


User currently offlineHorizonGirl From Canada, joined Mar 2005, 807 posts, RR: 15
Reply 21, posted (9 years 5 months 1 week 1 hour ago) and read 13352 times:

Thank you so much!!!!!!!!!!

I started this thread and brought up all the old PTU threads
for a school project I was doing on the A320.
I did very well, and I couldn't have done it with out
you all. Special thanks to everyone who gave me extra material and info.  bigthumbsup 
Once again, thank you.

Devon



Flying high on the Wings of the Great Northwest!
User currently offlineVC-10 From United Kingdom, joined Oct 1999, 3702 posts, RR: 34
Reply 22, posted (9 years 5 months 6 days 22 hours ago) and read 13344 times:
Support Airliners.net - become a First Class Member!

Quoting Klaus (Reply 5):
One forum member has once explained that Airbus explicitly wanted to have the PTU sound clearly audible to make troubleshooting on the ground easier. I don´t know if that´s exactly correct, but it might be an explanation. Newer versions are reported to be somewhat less noticeable (also from earlier threads).

It's a novel idea. I would have thought a look at the hyd pressure being generated by the PTU on ECAM would have been a more positive way of trouble shooting  Smile


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