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Transfer of hydraulic fluid


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Question for you guys. I have a c130h transferring fluid from the aux system to the utility system. Ive replaced the Ground test valve and the utility system accumulator (which had a leak internally). Neither of those parts solved it and it is still happening. Thoughts on where to go from here? 

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First question is what year/model?  Yes it matters if its a B-model verse a mid 80s H-model.

Ground test valve commonly considered bad for transfers and to be honest it almost never is.

Check the rigging to the ground test valve.  It should be tighter on one cable verse the other so that the valve wants to pull to the closed position.  The incorrect rigging of the cable is much more common than a valve itself.

Check the brake shuttle valves.  These can transfer aux to utility and utility to aux when brakes are used.  They should not allow fluid to flow through them once they shift to other side of shuttle.

A strange one that I have seen is one of the brake selector valves not receiving power to close so both valves were open and causing util/aux brake pressure to fight at the shuttle valves.  Its easy to check.  They are powered close so when energency is selected, you should have 28 vdc on normal selector and opposited when normal is selected.

Nose landing gear uplock, NLG actuator and nose gear emergency selector valve can also cause this.  Not too common but I have seen it.

Do you have UARRSI, refuel pods or weapons systems?  If so, all of those can be points of transfer.

Emergency brake and normal brake accumulators should be checked for internal leakage as well.

Most common of all is a person not fully depleting brake pressure on BOTH normal/emergency before moving the ground test.  There is always some avionics or electrics guy that wants to help but doesnt know the details of running hydraulics.   I have seen people chase this ghost and come to find out the new guy was improperly trained on tying ground test.

 

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13 hours ago, Leakybirds said:

Question for you guys. I have a c130h transferring fluid from the aux system to the utility system. Ive replaced the Ground test valve and the utility system accumulator (which had a leak internally). Neither of those parts solved it and it is still happening. Thoughts on where to go from here? 

 

Please See S NEWV9N2.pdf

Munir Abbasi

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  • 2 months later...

Thanks for the replies guys. It is a 92 h model. Since my post I have replaced normal selector valve, utility accumulator and ground test valve. Still having issues. Looking into emergency selector valve and shuttle valve  During flight of 8 hours its transferring 2 quarts from aux to utility. 

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45 minutes ago, Leakybirds said:

Thanks for the replies guys. It is a 92 h model. Since my post I have replaced normal selector valve, utility accumulator and ground test valve. Still having issues. Looking into emergency selector valve and shuttle valve  During flight of 8 hours its transferring 2 quarts from aux to utility. 

Dear It seem to (perhaps) ,your  mechanic were doing wrong ways for depleting the aircraft brake pressure without  energizing DC buses.

Munir Abbasi

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