Jet Blue A320 loses two hydraulic systems
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Fuel Dump
just to try to explain this fuel dump business/requirements.
Very few jets in domestic, medium range service need to have fuel dump/jettison capability.
the big thing is if you takeoff , lose an engine and have to return for landing...if your weight is too much to allow a safe go around on remaining engines, then you have a problem...and that problem is dealt with by dumping fuel.
landing overweight isn't so much the problem with the fuel dump requirement, it is the ability to do the go around after the engine out approach.
while there is a rare ability of some DC9's to dump fuel, the changeover in plane size is right around the 767...and some of the 767's DO NOT have fuel dump nor do they require it. but planes bigger than that (just a gudeline) usually have fuel dump capability.
Very few jets in domestic, medium range service need to have fuel dump/jettison capability.
the big thing is if you takeoff , lose an engine and have to return for landing...if your weight is too much to allow a safe go around on remaining engines, then you have a problem...and that problem is dealt with by dumping fuel.
landing overweight isn't so much the problem with the fuel dump requirement, it is the ability to do the go around after the engine out approach.
while there is a rare ability of some DC9's to dump fuel, the changeover in plane size is right around the 767...and some of the 767's DO NOT have fuel dump nor do they require it. but planes bigger than that (just a gudeline) usually have fuel dump capability.
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Airbus=total hydraulic failure=toast.
Pitothead, that`s rubbish. Look up OO-DLL hit by missile out of Baghdad. Left wing flap mangled beyond recognition, NO HYDRAULICS and landed on the runway with less than 2g recorded.
Pitothead, that`s rubbish. Look up OO-DLL hit by missile out of Baghdad. Left wing flap mangled beyond recognition, NO HYDRAULICS and landed on the runway with less than 2g recorded.
The Blue hyd system (elec pump + RAT backup) gives you control of the following:
Rudder
Elevators
Slats
Spoiler #3 L+R
Aileron L+R
If Yellow AND Green are gone you lose:
Trim control (yellow or green needed)
Yaw damper
Flaps
Stabilizer
NWS
Normal gear
Eng rev 1&2
Normal and Alt brakes
The latter is clearly (to me) the biggest problem - no brakes if both Green/Yellow are gone. All you have is any residual accumulator pressure. So my guess is that is why you'd what to get the aircraft as light as possible - all you've got are spoiler #3 both sides.
Rudder
Elevators
Slats
Spoiler #3 L+R
Aileron L+R
If Yellow AND Green are gone you lose:
Trim control (yellow or green needed)
Yaw damper
Flaps
Stabilizer
NWS
Normal gear
Eng rev 1&2
Normal and Alt brakes
The latter is clearly (to me) the biggest problem - no brakes if both Green/Yellow are gone. All you have is any residual accumulator pressure. So my guess is that is why you'd what to get the aircraft as light as possible - all you've got are spoiler #3 both sides.
Last edited by GarageYears; 20th Jun 2012 at 15:01. Reason: Originally had Flaps as available via Blue - incorrect. No flaps with only Blue.
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cptregjet
since you seem to know...is there any combination of two hydraulic failures that would leave the plane un controllable? is there a third standby?
and other than reducing weight, what reason could there be to hold for three hours...is resetting due to thermal problem possible.
I know in one jet I flew, we had a THERMAL CUT OUT OVER RIDE to use the hyd alternate system right away if needed.
since you seem to know...is there any combination of two hydraulic failures that would leave the plane un controllable? is there a third standby?
and other than reducing weight, what reason could there be to hold for three hours...is resetting due to thermal problem possible.
I know in one jet I flew, we had a THERMAL CUT OUT OVER RIDE to use the hyd alternate system right away if needed.
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GY,
Blue hydraulic can't drive the flaps,only the slats
Dual failure "only" can not lead to an uncontrolable aircraft....
Blue hydraulic can't drive the flaps,only the slats
Dual failure "only" can not lead to an uncontrolable aircraft....
Last edited by CptRegionalJet; 20th Jun 2012 at 14:06.
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captregional jet
so there is a yellow and green (eng?) and a blue system.
the blue system can give you normal aileron/spoiler, rudder and elevator?
there are reports that the plane was lurching about, with pax getting sick.
either the situation was worse than two hyd systems out, or real questions on three hour holding.
so there is a yellow and green (eng?) and a blue system.
the blue system can give you normal aileron/spoiler, rudder and elevator?
there are reports that the plane was lurching about, with pax getting sick.
either the situation was worse than two hyd systems out, or real questions on three hour holding.
@ CaptRegionalJet
Blue hydraulic can't drive the flaps,only the slats
FWIW Airbus test pilots have successfully landed the A320 family in manual backup multiple times during testing. That being said manual backup is designed to allow control of the a/c during systems recovery, not to perform a landing.
There is no double hydraulic failure that could lead to loss of control, and even a triple failure leaves the aircraft flyable. From memory the yellow system has an engine and electrical pump. The green has an engine pump and the two way ptu between the green and yellow. The blue has an electric pump and an auto deploying ram air turbine pump (that also supplies backup a/c electrics). There's plenty of redundancy, but a double failure is a red 'LAND ASAP' ECAM warning.
There is no double hydraulic failure that could lead to loss of control, and even a triple failure leaves the aircraft flyable. From memory the yellow system has an engine and electrical pump. The green has an engine pump and the two way ptu between the green and yellow. The blue has an electric pump and an auto deploying ram air turbine pump (that also supplies backup a/c electrics). There's plenty of redundancy, but a double failure is a red 'LAND ASAP' ECAM warning.
Fill your boots:
Well, so much for 5000 hours of Airbus experience, then. 
Mechanical back-up is rudder and trim - both need hydraulic pressure to work, so a triple hydraulic failure leaves you with NO flying controls (including trim). You have engine thrust, gear extension and passengers running forward and rearward for control - i.e. None.
(Mechanical back-up is designed to provide a minimum of control following a complete loss of electrical power (side sticks don't work!) - i.e. before you can get the RAT deployed, and the emergency generator up to speed.)
Originally Posted by Locked door
and even a triple failure leaves the aircraft flyable.
Mechanical back-up is rudder and trim - both need hydraulic pressure to work, so a triple hydraulic failure leaves you with NO flying controls (including trim). You have engine thrust, gear extension and passengers running forward and rearward for control - i.e. None.
(Mechanical back-up is designed to provide a minimum of control following a complete loss of electrical power (side sticks don't work!) - i.e. before you can get the RAT deployed, and the emergency generator up to speed.)
Last edited by Checkboard; 20th Jun 2012 at 16:19.
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FWIW Airbus test pilots have successfully landed the A320 family in manual backup multiple times during testing. That being said manual backup is designed to allow control of the a/c during systems recovery, not to perform a landing.
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Airbus=total hydraulic failure=toast.
Pitothead, that`s rubbish. Look up OO-DLL hit by missile out of Baghdad. Left wing flap mangled beyond recognition, NO HYDRAULICS and landed on the runway with less than 2g recorded.
Pitothead, that`s rubbish. Look up OO-DLL hit by missile out of Baghdad. Left wing flap mangled beyond recognition, NO HYDRAULICS and landed on the runway with less than 2g recorded.
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Thats true but it makes not one iota of difference if it`s fly-by-wire or not. The 320 is inherently a very stable airframe as shown by multiple manual landings during the flight test stage. Besides, your statement only said Airbus.
Dog Tired
I have seen (and done) many, many sim landings off the ILS - just for confidence building - in mechanical back-up. Power for pitch control by one pilot and rudder/pitch trim by the other.
Try it.
Try it.
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Thats true but it makes not one iota of difference if it`s fly-by-wire or not.