PPRuNe Forums - Hydraulics

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not a fixed amount, depends on flight time, height and so on, like fuel

Complete bull!

It gets serviced, refilled to a limit and so on. It is not dependent on the variables above and in no way like fuel...

Nic

Admiral,

If you look at bumpys posts (all made today) there is not a lot of sense being made! :rolleyes:

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How much Hyd fluid do the jets carry?

I don't know exactly, but I have been told it's not a whole lot. Force is crosssection by pressure, and those 3000psi are doing the job - saves weight!

Nic

Max fill for an A319.

Green 14.5L, Yellow 12.5L & Blue 6.5L.

Amount reflects the amount of users each system has. Green sys powers landing gear retraction for example.

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Amount reflects the amount of users each system has.

It only reflects the amount in the resevoir, the system contains alot more.

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Max fill for an A319.

Green 14.5L, Yellow 12.5L & Blue 6.5L.

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It only reflects the amount in the resevoir, the system contains alot more.

The A320 series (318-319-320-321) hydraulic systems hold 235 Liters (62 Gallons) of fluid:

100 liters (26 gallons) in the Green system.

75 liters (20 gallons) in the Yellow system.

60 liters (16 gallons) in the Blue system.

Glhcarl & Muduckace,

Thanks for the info. You learn something new every day!!:ok:

Fluid cooling by fuel heat exchanger is a Boeing concept. Airbus uses fluid cooling by flow thru metal tubing exposed to outside air.

Thanks for that I did wonder about hyd fluid as a consumable.

Thanks for the data. Do Boeing types use more of the stuff for a similar sized aircraft?

And for the orginal OP on my type the hyd temp warning comes on at 90 deg C.

And large earnthmovers/diggers the operators have been known to cook chickens on the hyd tanks.

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Complete bull!

It gets serviced, refilled to a limit and so on. It is not dependent on the variables above and in no way like fuel...

Second the motion on the complete bull...wonder where some guys get these ideas?
As for total quantity, seem to remember 48 USGallons total hydraulic fluid capacity on the L1011.

From the 747 Maintenance Manual;

CAUTION:
DURING OPERATIONS INVOLVING HYDRAULIC SYSTEMS PRESSURIZATION, RELATED INSTRUMENTS AND INDICATING LIGHTS IN THE FLIGHT COMPARTMENT SHOULD BE CLOSELY MONITORED TO ASSURE SATISFACTORY OPERATION OF SYSTEM. IF HYDRAULIC FLUID OVERHEAT CONDITION OCCURS, SYSTEM OPERATION SHOULD BE DISCONTINUED.
DO NOT OPERATE TRAILING EDGE FLAPS MORE THAN TWO CYCLES IN A 15 MINUTE PERIOD. SYSTEM LOADING CONDITIONS CAN OVERHEAT HYDRAULIC FLUID.

Check for a minimum of 300 gallons (2000 pounds; 900 kilograms) of fuel in each No. 1 and 4 main fuel tanks, and 805 gallons (5400 pounds, 2450 kilograms) in each No. 2 and 3 main fuel tanks.
NOTE: If the applicable tank has the minimum amount of fuel, there is no time limit on the operation of the hydraulic pump. If there is less fuel than the minimum amount, the hydraulic pump operation is limited to 15 minutes.

CAUTION: TO PREVENT HYDRAULIC FLUID OVERHEAT, DO NOT OPERATE PUMPS AFTER OVERHEAT LIGHT COMES ON OR LONGER THAN 15 MINUTES WITHOUT MINIMUM QUANTITIES OF FUEL IN TANKS. ALLOW 20-MINUTE COOLING PERIOD AFTER 15-MINUTE OPERATION OR AFTER OVERHEAT LIGHT GOES OUT. WHEN AMBIENT TEMPERATURE EXCEEDS 100¡F, OPEN NACELLE STRUT FAIRING DOORS. EXTREME TEMPERATURES AND LOAD CONDITIONS CAN OVERHEAT HYDRAULIC FLUID.

The above outlines operations in the Maintenance environment and it would be extremely unlikely to encounter a hydraulic overheat and near to impossible in a "Flight" condition. But like anything in aviation, "It's possible"

:ok:
.

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some aircraft have heat exchangers in the fuel tanks requiring a minimum amount of fuel for cooling

Not all of the hydraulic fluid passes through the heat exchangers. Only the portion of the hydraulic fluid that circulates through the pumps for cooling and lubrication is passed through the heat exchangers.

Read "Fate is the Hunter" , "A hole" and Gann's memory of Ross and the matches.

After an excellent landing etc...

Another Troll alert

In my considered and learned opinion, bumpyflight is yet another in the outbreak of pests we have seen lately. Must be the warm weather. Best ignored?.

As I recall, AF recycled an A340 this way: Forgot to switch off the pump, towed her around CDG, overheat condition led to a/c fire which was damaged beyond repair and written off.

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Doesn't all the hydraulic fluid pass through the pump sooner or later?

5080 psi system on A380 requires more cooling.There are 2 double air-oil
heatexchangers with hyd motors driven fans (ground & low speed).As a
backup 2 fuel-oil heatexchangers are installed.

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Doesn't all the hydraulic fluid pass through the pump sooner or later?

Yes of course it does, however, within the pump, a small portion of the fluid is diverted to circulate around the pump for cooling and lubrication. If you happen to be standing around any Boeing and the engine cowlings are open, look at the hydraulic pump. You will see 3 lines. One is supply, one is pressure and the last one is marked case drain. This is the cooling and lubrication drain. That fluid is routed through the fuel tank heat exchanger before returning to the reservoir. The hydraulic fluid used to do the actual work returns directly to the reservoir and is cooled as it passes through the return lines.

It was that drain return which caused the incident I had with the base plate seperating from the pump body pulling the studs from the casting. A none return valve packed in and became a valve in the closed position q a whore of a lot of noise a big bang and tons of smoke. Our ginger was in the back as well when it blew. It was the most emotional and expressive I have ever seen him with a tech problem.