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A330 Hyd. Transfer  
User currently offlineA10WARTHOG From United States of America, joined Jul 2004, 325 posts, RR: 0
Posted (5 years 9 months 1 week 1 day 12 hours ago) and read 5084 times:

I was reading on a Website Smart Cockpit, that the A330 has no way that there can be hydraulic transfer from one system to another. The aircraft I have worked on said the same, but the reality is that you do get transfer of hydraulic fluid through the brake system (shuttle valves). Is this the reality with the A330 or any other of the Airbus models?

I have never worked on an Airbus before and I know that the website may not be 100% correct.

22 replies: All unread, jump to last
 
User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 68
Reply 1, posted (5 years 9 months 1 week 1 day 12 hours ago) and read 5075 times:

I've heard that statement regarding other jets as well, though I cannot think of any specific examples. It is kind of a 'gee whiz' factiod and the amount is not sufficient to change anything. It is therefore, pretty well ignored. Groundschools rarely even mention such minutiae anymore. It is not quite up there with "how far aft does the speed of flight shift the light from the logo light on the tail?" but it is certainly not a legitimate oral question.


Happiness is not seeing another trite Ste. Maarten photo all week long.
User currently offlineA10WARTHOG From United States of America, joined Jul 2004, 325 posts, RR: 0
Reply 2, posted (5 years 9 months 1 week 1 day 11 hours ago) and read 5061 times:



Quoting SlamClick (Reply 1):
It is kind of a 'gee whiz' factiod and the amount is not sufficient to change anything. It is therefore, pretty well ignored. Groundschools rarely even mention such minutiae anymore.

For pilot maybe they would not care, but as a mechanic if it transferred one way, you can bring it back the other. It can be the difference between over serviced system and normal and the difference between needing a service cart or not. The EMB-145 and 777 both will transfer hyd. fluid.


User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 3, posted (5 years 9 months 1 week 1 day 11 hours ago) and read 5055 times:

If there are any hydraulic components that are powered by more then one system, fluid transfer is always possible. Example, if a servo (aileron, rudder, etc) is powered by two or more hydraulic systems can leak internally, transferring fluid from one system to another.

User currently offlineA10WARTHOG From United States of America, joined Jul 2004, 325 posts, RR: 0
Reply 4, posted (5 years 9 months 1 week 1 day 10 hours ago) and read 5036 times:

I understand that, I was just curious if what the website say, which the information looks like it can from a Airbus flight crew training manual, is reality or not. I would suspect that if you operate the system in a certain way you would get transfer.

User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 79
Reply 5, posted (5 years 9 months 1 week 1 day 4 hours ago) and read 4960 times:



Quoting 474218 (Reply 3):
If there are any hydraulic components that are powered by more then one system, fluid transfer is always possible. Example, if a servo (aileron, rudder, etc) is powered by two or more hydraulic systems can leak internally, transferring fluid from one system to another.

The key there is if they can leak internally...there are some designs that can't. As understand the OP's question, we're talking about when everything is working normally.

Tom.


User currently offlineBuckFifty From Canada, joined Oct 2001, 1316 posts, RR: 19
Reply 6, posted (5 years 9 months 1 week 1 day 2 hours ago) and read 4943 times:

As I understand it, the A330 braking system are run off separate hydraulic systems for each individual braking pot/cylinder, fed from individual hydraulic lines. If the green system is powering the brakes, only certain cylinders will activate under all conditions. If the alternate (blue) systems is active (either park brake or alternate braking), then the other cylinders will operate. Neither system will share any braking components together, so I don't think it's possible.

User currently offlineZeke From Hong Kong, joined Dec 2006, 9109 posts, RR: 75
Reply 7, posted (5 years 9 months 1 week 1 day 1 hour ago) and read 4938 times:



Quoting A10WARTHOG (Thread starter):
The aircraft I have worked on said the same, but the reality is that you do get transfer of hydraulic fluid through the brake system (shuttle valves). Is this the reality with the A330 or any other of the Airbus models?

I do not think is possible on the 330/340, but what you describe is possible on the 320 and was used if they overfilled one system.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineA10WARTHOG From United States of America, joined Jul 2004, 325 posts, RR: 0
Reply 8, posted (5 years 9 months 1 week 1 day ago) and read 4936 times:



Quoting BuckFifty (Reply 6):
As I understand it, the A330 braking system are run off separate hydraulic systems for each individual braking pot/cylinder, fed from individual hydraulic lines. If the green system is powering the brakes, only certain cylinders will activate under all conditions. If the alternate (blue) systems is active (either park brake or alternate braking), then the other cylinders will operate.

That would be the difference between the 2 aircraft I used as an example. Thanks for the info


User currently offlineJetMech From Australia, joined Mar 2006, 2699 posts, RR: 53
Reply 9, posted (5 years 9 months 1 week 19 hours ago) and read 4914 times:



Quoting BuckFifty (Reply 6):

Yep. IIRC, every alternate piston on an A330 brake unit is powered by one of two hydraulic systems. I don't think there is any interconnection

Quoting A10WARTHOG (Thread starter):

We used to transfer fluid through the brakes on the 767.

Regards, JetMech



JetMech split the back of his pants. He can feel the wind in his hair.
User currently offlineBoeing767mech From United States of America, joined Dec 2000, 1027 posts, RR: 3
Reply 10, posted (5 years 9 months 1 week 19 hours ago) and read 4911 times:



Quoting JetMech (Reply 9):
We used to transfer fluid through the brakes on the 767.

Regards, JetMech

Same with the 757's

David



Never under-estimate the predictably of stupidty
User currently offlineTristarSteve From Sweden, joined Nov 2005, 4009 posts, RR: 33
Reply 11, posted (5 years 9 months 1 week 18 hours ago) and read 4898 times:



Quoting Zeke (Reply 7):
Quoting A10WARTHOG (Thread starter):
The aircraft I have worked on said the same, but the reality is that you do get transfer of hydraulic fluid through the brake system (shuttle valves). Is this the reality with the A330 or any other of the Airbus models?

I do not think is possible on the 330/340, but what you describe is possible on the 320 and was used if they overfilled one system.

The A320 also has double sets of brake pistons. All Airbus brakes I have seen are the same. separate sets of pistons for each brake system, and no shuttle valves.
All Boeings I have worked on B737 B757 B767 B747 B777 have a single set of pistons, and shuttle valves.
Because of the design of the park brake system, Boeing park brake pressure decays quite fast. After 8 hours it will be down at acc pressure (1000psi). As the pressure drops the fluid returns to the tank. The first hyd pump that is turned on will fill up the parking system. So to avoid transfer you have to train pilots to turn on the park brake sys hyd pump first.
Because the B757 and B767 have similar cockpits, the same crews, but different braking systems, fluid transfer is very prevalant on the B757.

Airbus park brake system does not transfer fluid, and it keeps its pressure. If the park brake pressure on an A320 has decayed overnight, there is a defect.


User currently offlineZeke From Hong Kong, joined Dec 2006, 9109 posts, RR: 75
Reply 12, posted (5 years 9 months 1 week 14 hours ago) and read 4843 times:



Quoting TristarSteve (Reply 11):
The A320 also has double sets of brake pistons. All Airbus brakes I have seen are the same. separate sets of pistons for each brake system, and no shuttle valves.

If it a 320 with NWS on yellow, it will not have a shuttle valve (would also have the Alternate Braking Control Unit installed), if the NWS is on the green, it does have a shuttle valve and no ABCU.

I think it is standard now on new builds not to have a shuttle valve, the mod was introduced not that long back, maybe 2-3 years ago.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineTristarSteve From Sweden, joined Nov 2005, 4009 posts, RR: 33
Reply 13, posted (5 years 9 months 1 week 13 hours ago) and read 4824 times:

We have both. In fact we have A320 from 1988 and Dec 2008.
But although the older A320 has a shuttle valve it is fundamentally different from the Boeing shuttle valve. the A320 shuttle valve is kept closed by green sys pressure, and opens when that pressure falls, allowing yellow pressure into the alt braking system. This alt braking system is totally independent with its own return lines.
On the Boeing, the shuttle valve when open ports alt brake sys fluid into the normal brake lines and pistons. This then returns to the normal sys reservoir.


User currently offlineZeke From Hong Kong, joined Dec 2006, 9109 posts, RR: 75
Reply 14, posted (5 years 9 months 1 week 12 hours ago) and read 4801 times:



Quoting TristarSteve (Reply 13):
But although the older A320 has a shuttle valve it is fundamentally different from the Boeing shuttle valve. the A320 shuttle valve is kept closed by green sys pressure, and opens when that pressure falls, allowing yellow pressure into the alt braking system. This alt braking system is totally independent with its own return lines.

I seem to recall a way of transferring fluid from one yellow to green by pumping the brakes when the park brake off when the aircraft was chocked at the gate, I remember the mechanics doing that when they overfilled the yellow. Seem to recall this would not work normally due to engine bleed pressure closing a valve. Remember having to do the pre flight alternate brake checks etc on them had something to do with this as well.

What do you do if you overfill the yellow ?

Forgive me for being sketchy, I have not flown the 320 for well over a decade.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineTristarSteve From Sweden, joined Nov 2005, 4009 posts, RR: 33
Reply 15, posted (5 years 9 months 1 week 10 hours ago) and read 4781 times:



Quoting Zeke (Reply 14):
I seem to recall a way of transferring fluid from one yellow to green by pumping the brakes when the park brake off when the aircraft was chocked at the gate

I have not heard of that, will ask around at work next week.
We do it all the time on Boeings, but I have never had to on an A320.
I can't remember an A320 transferring fluid.


User currently offlineA10WARTHOG From United States of America, joined Jul 2004, 325 posts, RR: 0
Reply 16, posted (5 years 9 months 6 days 6 hours ago) and read 4631 times:

Guys thanks for the responses. You cured my curiosity for the day. It was interesting to learn how the brakes are designed on the Airbus. Like I said never have worked on them.

User currently offlineRoseFlyer From United States of America, joined Feb 2004, 9649 posts, RR: 52
Reply 17, posted (5 years 9 months 6 days 1 hour ago) and read 4601 times:



Quoting TristarSteve (Reply 11):
The first hyd pump that is turned on will fill up the parking system. So to avoid transfer you have to train pilots to turn on the park brake sys hyd pump first.

On the 737, only the B system can pressurize the accumulator which can pressurize the parking brake when the hydraulic pumps are off.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineVAAengineer From United States of America, joined Jul 2007, 90 posts, RR: 0
Reply 18, posted (5 years 9 months 5 days 1 hour ago) and read 4489 times:

No Hyd fluid transfers on ANY Airbus is possible.


God's Gift To Aviation
User currently offlineAC320tech From Canada, joined Jul 2006, 197 posts, RR: 1
Reply 19, posted (5 years 8 months 3 weeks 3 days 23 hours ago) and read 4215 times:



Quoting VAAengineer (Reply 18):
No Hyd fluid transfers on ANY Airbus is possible.

What about Power Transfer (PTU)?


User currently offlineLarshjort From Denmark, joined Dec 2007, 1475 posts, RR: 0
Reply 20, posted (5 years 8 months 3 weeks 3 days 21 hours ago) and read 4195 times:



Quoting AC320tech (Reply 19):

What about Power Transfer (PTU)?

Doesn't transfer hud fluid, only presuure

/Lars



139, 306, 319, 320, 321, 332, 34A, AN2, AT4, AT5, AT7, 733, 735, 73G, 738, 739, 146, AR1, BH2, CN1, CR2, DH1, DH3, DH4,
User currently offlineCelticMech From Ireland, joined Oct 2008, 216 posts, RR: 3
Reply 21, posted (5 years 8 months 2 weeks 6 days 16 hours ago) and read 3959 times:

No Hydrulic Fluid transfer is possible on the A330/A340 aircraft. For info the Brakes comprise of 14 separate cylinders...7 of them powered by Green Sys (normal braking) and 7 by the Blue (alternate and parking brake). If you even look at the brake sys schematics you will see its not possible for a tx of fluid.
Some people are asking about the PTU...maybe they are confusing this in the sense that the PTU can transfer Power (i.e. energy) but it doesnt actually transfer the Fluid. I.e. on the 320/321 the Yellow and green system and on the 737NG's the A and B systems.. IF i remember correctly from Ch 29, the PTU comprises of a Pump and a Motor...B sys connects on the Pump side and A on the Motor side....any ideas anyone??


User currently offlinePart147 From Ireland, joined Dec 2008, 499 posts, RR: 0
Reply 22, posted (5 years 8 months 2 weeks 5 days 20 hours ago) and read 3871 times:

A PTU has two rotating elements connected by a single shaft... On the 'powered' or 'driving' side, there is a 'turbine' which spins due to the pressurised hydraulic flow - on the other side, a type of 'compressor' (It's not a compressor though!!!!) drives the secondary system by causing the fluid to flow. A clever and simple solution!

This means you get a 'power' transfer - but NO fluid flow from one system to the other!

Just to clarify one other point mentioned above - a simple shuttle valve design does not allow fluid transfer from one system to the other. They link two separate hydraulic supply systems to one service, such as brakes, and only allow the system with the highest pressure to supply that service. It's like two non-return valves (check valves) that share a common exit pipeline, keeping 'normal' and 'emergency' systems separate.



It's better to ask a stupid question during training, rather than make a REALLY stupid mistake later on!
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