A320: Hyd G + Y system low pressure
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A320: Hyd G + Y system low pressure
I am still learning this machine....
I was going through the HYD G + Y LO PR SUMMARY in the eQRH and got stuck at this:
When in CONF3 and VAPP:
Stabilize at VAPP before L/G down, to be trimmed for approach:
To me that insinuates that trimming is possible, but the THS is moved by hydraulic motors driven by G and Y sys. The very two systems that are not operating!? As we're (likely) in alternate law I would have thought the F/CTL system is now maintaining Load Factor demand with elevator only through the operative B system. The THS is stuck in the last position where G or Y hydraulics was available. As we select L/G down and go into direct law (direct stick to elevator relationship), that will likely result in an out of trim condition.
Am I right in reasoning? If so, use of the words trimmed for approach sounds misleading.
Any ideas are welcome.
I was going through the HYD G + Y LO PR SUMMARY in the eQRH and got stuck at this:
When in CONF3 and VAPP:
Stabilize at VAPP before L/G down, to be trimmed for approach:
To me that insinuates that trimming is possible, but the THS is moved by hydraulic motors driven by G and Y sys. The very two systems that are not operating!? As we're (likely) in alternate law I would have thought the F/CTL system is now maintaining Load Factor demand with elevator only through the operative B system. The THS is stuck in the last position where G or Y hydraulics was available. As we select L/G down and go into direct law (direct stick to elevator relationship), that will likely result in an out of trim condition.
Am I right in reasoning? If so, use of the words trimmed for approach sounds misleading.
Any ideas are welcome.
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The trimming is done through the elevator only.
It's described in the FCTM. Search for Dual Hydraulic failures.
Look at note 1 of the remaining systems.
Hope that helps.
It's described in the FCTM. Search for Dual Hydraulic failures.
Look at note 1 of the remaining systems.
Hope that helps.
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Thanks Field In Sight, the part about the system memorizing elevator position cleared it up for me!!
For anyone interested, this is note 1:
The stabilizer is lost. In alternate law, the auto trim function is provided through the elevators. At landing gear extension, switching to direct law, the auto trim function is lost. However, the mean elevator position at that time is memorized, and becomes the reference for centered sidestick position. This is why, in order to ensure proper centered sidestick position for approach and landing, the procedure requires to wait for stabilization at VAPP, before landing gear extension.If this procedure is missed, the flare and pitch control in case of go-around may be difficult.
For anyone interested, this is note 1:
The stabilizer is lost. In alternate law, the auto trim function is provided through the elevators. At landing gear extension, switching to direct law, the auto trim function is lost. However, the mean elevator position at that time is memorized, and becomes the reference for centered sidestick position. This is why, in order to ensure proper centered sidestick position for approach and landing, the procedure requires to wait for stabilization at VAPP, before landing gear extension.If this procedure is missed, the flare and pitch control in case of go-around may be difficult.
