Air India Airbus 319 Suspected Triple Hydraulic Failure
On A319. Assume A320 is same in this area, although there are some odd little variations.
The rudder trim control is electrically signalled. An electric actuator installed in the tail area drives a trim screwjack via a rotary shaft and universal joints. The actuator is manually controlled via the FACs (Ref. ATA 22) from the control panel located on the center pedestal, at a constant speed.
Last edited by compressor stall; 16th Jul 2012 at 11:19.
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Once again, FCOM 1-27-10:
Trim is electrically demanded but Hydraulically actuated.
in addition the following:
The electrical actuators effectively 'reposition' the cetre point of the Hydraulic actuator thus providing trim. This can be seen by the line ' In addition to limitation by TLU, if rudder trim is applied, maximum rudder deflection may be reduced in the opposite direction.' which demonstrates how the rudder trim is achieved by offsetting the neutral position.
Upshot? Rudder trim is not available in a total hydraulic loss. Back to differential thrust I'm afraid.
Trim is electrically demanded but Hydraulically actuated.
Yaw axis
Rudder = Mechanical, however control for yaw damping, turn coordination and trim
is electrical.
Rudder = Mechanical, however control for yaw damping, turn coordination and trim
is electrical.
RUDDER TRIM
The two electric motors that position the artificial feel unit also trim the rudder. In normal
operation, motor N 1, controlled by FAC1, drives the trim, and FAC2 with motor N 2 remains
synchronized as back-up.
In manual flight, the pilot can apply rudder trim with the rotary RUD TRIM switch on the
pedestal.
– Maximum deflection is ± 25.
– Rudder trim speed is one degree per second.
– In addition to limitation by TLU, if rudder trim is applied, maximum rudder deflection may
be reduced in the opposite direction.
The pilot can use a button on the RUD TRIM panel to reset the rudder trim to zero.
Note: With the autopilot engaged, the FMGC computes the rudder trim orders. The rudder
trim rotary switch and the rudder trim reset pushbutton are not active.
The two electric motors that position the artificial feel unit also trim the rudder. In normal
operation, motor N 1, controlled by FAC1, drives the trim, and FAC2 with motor N 2 remains
synchronized as back-up.
In manual flight, the pilot can apply rudder trim with the rotary RUD TRIM switch on the
pedestal.
– Maximum deflection is ± 25.
– Rudder trim speed is one degree per second.
– In addition to limitation by TLU, if rudder trim is applied, maximum rudder deflection may
be reduced in the opposite direction.
The pilot can use a button on the RUD TRIM panel to reset the rudder trim to zero.
Note: With the autopilot engaged, the FMGC computes the rudder trim orders. The rudder
trim rotary switch and the rudder trim reset pushbutton are not active.
Upshot? Rudder trim is not available in a total hydraulic loss. Back to differential thrust I'm afraid.
Last edited by Wirbelsturm; 16th Jul 2012 at 15:06.
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ok folks...ALL primary flight control surfaces on ANY 318.319,320,321,330,340......are hydraulically actuated....no hydraulics...no move....some MAY be electrically or mechanically controlled, but all require hydraulic pressure to move......simple
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Wot he above said!
Electically controlled, hydraulically actuated.
Anyway, according to airbus Politicians will be upfront and honest before a triple hydraulic failure occurs. So we're all safe!
Electically controlled, hydraulically actuated.
Anyway, according to airbus Politicians will be upfront and honest before a triple hydraulic failure occurs. So we're all safe!
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No, no residual pressure. Why would the digital indicator move but not the surface? I admit that all I saw move was the trim on the FLT CTL page.
An additional method on the A320 is to use the electric rudder trim to control laterally - it requires no hydraulics.
Rudder is hydraulical actuated. There is now mechanical or electrical back-up for that Hydraulic-Actuators!!!
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Thanks to Wirbelstrum and ironbutt57 for your helpful, unpatronising inputs. As for the likes of LandASAP, your response is why you are no doubt not a trainer. Learning/ making mistakes with the oversight of more experienced pilots is how I've instilled some of my firmest knowledge.
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After a life on Boeings, one wise Airbus person gave me words to live by..."when it's all working it's fantastic, when it goes wrong it REALLY goes wrong".....how very very true...
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Originally Posted by BlackandBrown
Why would the digital indicator move but not the surface?
Worth remembering that the same applies to all Boeing models after the 737 which was the last design to have true "manual reversion" in the elevator and aileron controls. It could be flown and landed, with effort and planning, with no hydraulic power.
I have had a go at thrust only control in a 320 sim and it can be flown around the sky without too much trouble after a bit of practice but I found a "walk away from" landing was impossible to achieve if starting clean with the gear up. If you failed everything with gear down and some flap out it was possible to arrive on the ground in about the right place, not pretty but survivable. My respect for the few who have pulled it off in real life is immense.
I have had a go at thrust only control in a 320 sim and it can be flown around the sky without too much trouble after a bit of practice but I found a "walk away from" landing was impossible to achieve if starting clean with the gear up. If you failed everything with gear down and some flap out it was possible to arrive on the ground in about the right place, not pretty but survivable. My respect for the few who have pulled it off in real life is immense.
LandASAP
There was a time pilots got "hands on" explanation of the mechanical parts of planes, how they functioned, what the inputs were and so on. Now, it's all, "if you can't fix or touch it, you don't need to know it" which is quite incomplete.
There was a time pilots got "hands on" explanation of the mechanical parts of planes, how they functioned, what the inputs were and so on. Now, it's all, "if you can't fix or touch it, you don't need to know it" which is quite incomplete.
