DHC8 mod 8-2781
11-23-2011, 07:19 AM
#1
omniairialist
Thread Starter
Joined APC: Mar 2011
Position: Pineapple Pilot
Posts: 13
DHC8 mod 8-2781
With this mod, DHC incorporated a ISO VLV in order to isolate the rudder from the rest of the hydraulic consumers.
The hydraulic Isolation Valve closes when there is a low quantity in the hydraulic reservoir, and the HYD ISO VLV caution light illuminates.
If the leak continues - the hydraulic reservoir will be emptied and the Engine driven pump will have no fluid to pump and the ENG HYD PUMP caution light will illuminate.
This is what I know.
My question is - does the HYD ISO VLV open again when the reservoir is completely empty?
The sim that I am in right now does that.
The checklist for complete hydraulic failure reads - ENG HYD PUMP and HYD ISO VLV illuminated - which leads me to believe that the HYD ISO VLV should be on.
Any ideas? References?
The hydraulic Isolation Valve closes when there is a low quantity in the hydraulic reservoir, and the HYD ISO VLV caution light illuminates.
If the leak continues - the hydraulic reservoir will be emptied and the Engine driven pump will have no fluid to pump and the ENG HYD PUMP caution light will illuminate.
This is what I know.
My question is - does the HYD ISO VLV open again when the reservoir is completely empty?
The sim that I am in right now does that.
The checklist for complete hydraulic failure reads - ENG HYD PUMP and HYD ISO VLV illuminated - which leads me to believe that the HYD ISO VLV should be on.
Any ideas? References?
11-23-2011, 08:02 AM
#2
Gets Weekends Off
Joined APC: Jan 2008
Posts: 408
Pardon me cause I'm typing from my phone, but with the illumination of the HYD ISO VLV light it means the valve has worked properly and you still have about a half quart of fluid in the system. The only thing that will still function on the respective system is the rudder actuator. If you had a complete HYD failure and the ISO valve fails I would not expect to see the HYD ISO VLV caution light and quantity would obviously read 0.
11-23-2011, 10:21 AM
#5
Gets Weekends Off
Joined APC: Jan 2008
Posts: 408
If you have a complete loss of fluid that means the ISO valves did not work and you will not see the HYD ISO VLV caution.. So to answer your question with complete loss.. You will only have ENG HYD PUMP.
If you see a HYD ISO VLV you do not have a complete loss only a partial loss.
If you see a HYD ISO VLV you do not have a complete loss only a partial loss.
11-23-2011, 11:17 AM
#8
omniairialist
Thread Starter
Joined APC: Mar 2011
Position: Pineapple Pilot
Posts: 13
Originally Posted by piper338
If you have a complete loss of fluid that means the ISO valves did not work and you will not see the HYD ISO VLV caution.. So to answer your question with complete loss.. You will only have ENG HYD PUMP.
If you see a HYD ISO VLV you do not have a complete loss only a partial loss.
If you see a HYD ISO VLV you do not have a complete loss only a partial loss.
Then the iso valve would close in response to the low fluid quantity, the leak would continue until all fluid is drained. Then the ENG HYD PUMP light would come on due to low output pressure from the EDP.
Would the ISO VLV stay closed in this instance?
Would the ISO VLV caution light stay on?
The sim responds with an initial ISO VLV light
then when the reservoir is empty the HYD PUMP light comes on and the ISO VLV extinguishes.
Is that correct.
I am mostly familiar with a Q400 and I know what that aircraft does, I am just wondering what the 100-300 will do/is intended to do?
It is a 100 simulator that I am working with.
11-23-2011, 11:50 AM
#9
Gets Weekends Off
Joined APC: Jan 2008
Posts: 408
That's just a bad day when that happens.... Honestly I don't know.
I think it would open and the light go out in that instance just because it is a float switch. Can't "float" with no fluid...
Just a guess, I'd go test it out but I might get into some trouble.
I think it would open and the light go out in that instance just because it is a float switch. Can't "float" with no fluid...
Just a guess, I'd go test it out but I might get into some trouble.
11-23-2011, 01:50 PM
#10
Don't need that HUD!
Joined APC: Mar 2008
Position: B777/B787 - Air Carrier Technical Pilot
Posts: 314
Originally Posted by omniair
what if the leak is in a rudder actuator?
Then the iso valve would close in response to the low fluid quantity, the leak would continue until all fluid is drained. Then the ENG HYD PUMP light would come on due to low output pressure from the EDP.
Would the ISO VLV stay closed in this instance?
Would the ISO VLV caution light stay on?
Then the iso valve would close in response to the low fluid quantity, the leak would continue until all fluid is drained. Then the ENG HYD PUMP light would come on due to low output pressure from the EDP.
Would the ISO VLV stay closed in this instance?
Would the ISO VLV caution light stay on?
If there is a leak in the rudder actuator, then when the float switch in the reservoir activates: 1) the ISO VLV stays closed. 2) the ISO VLV caution light remains illuminated. 3) the ENG HYD PUMP caution light illuminates due to low output pressure from the EDP. 4) other associated rudder caution lights will also illuminate and remain on such as RUD PRESS and RUD FULL PRESS.
Originally Posted by omniair
The sim responds with an initial ISO VLV light
then when the reservoir is empty the HYD PUMP light comes on and the ISO VLV extinguishes.
Is that correct.
then when the reservoir is empty the HYD PUMP light comes on and the ISO VLV extinguishes.
Is that correct.
Last edited by trent890; 11-23-2011 at 02:18 PM.
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