ADC inputs
Joined: Jun 2005
Posts: 954
Likes: 5
From: USA
Representative 2nd and 3rd generation EFIS digital ADC inputs/outputs:
(Various airplane types may combine functions or vary considerably.)
The Lear 60 Digital Air Data Computers utilize sensor inputs from:
-static pressure ports
-pitot pressure probes
-TAT probe
Each DADC provides the following outputs directly to it's respective DPU:
-airspeed/mach
-altitude
-vertical speed
-SAT
-TAS
-over/under speed cues
Air data is also used by FADECs, mach trim, pressurization controller, gear warning, XPDR and a number of other air data dependent systems. FMS can compute ADC inputs to calculate a number of other air data values as well.
In the 60, the AOA vanes and indicators are two completely separate systems independent of each other. An AOA indicator is installed at each pilot station. AOA inputs are used by the stall computers to generate stall warning and to display 1.3 Vs (green line) on the PFD airspeed indicators. Flap position signals are used to bias the indicated AOA, 1.3 Vs display and stall warning activation threshold. An ADC >18,100' signal triggers a 15 kt additive to account for high altitude IAS/EAS differential.
So in short no, the AOA is not an ADC input, but may be used along with air data for certain purposes such as stall warning/recognition.
Hope this info was helpful.
westhawk
(Various airplane types may combine functions or vary considerably.)
The Lear 60 Digital Air Data Computers utilize sensor inputs from:
-static pressure ports
-pitot pressure probes
-TAT probe
Each DADC provides the following outputs directly to it's respective DPU:
-airspeed/mach
-altitude
-vertical speed
-SAT
-TAS
-over/under speed cues
Air data is also used by FADECs, mach trim, pressurization controller, gear warning, XPDR and a number of other air data dependent systems. FMS can compute ADC inputs to calculate a number of other air data values as well.
In the 60, the AOA vanes and indicators are two completely separate systems independent of each other. An AOA indicator is installed at each pilot station. AOA inputs are used by the stall computers to generate stall warning and to display 1.3 Vs (green line) on the PFD airspeed indicators. Flap position signals are used to bias the indicated AOA, 1.3 Vs display and stall warning activation threshold. An ADC >18,100' signal triggers a 15 kt additive to account for high altitude IAS/EAS differential.
So in short no, the AOA is not an ADC input, but may be used along with air data for certain purposes such as stall warning/recognition.
Hope this info was helpful.
westhawk
Joined: Mar 2001
Posts: 4,563
Likes: 35
From: I wouldn't know.
The AoA vane input is used in the 737 ADC. A failure of said AoA will result in completely wrong speeds and altitudes. It even affects GS and W/V displays, all are wrong.
We had a few incidents (one causing a RWY overrun) due to stuck AoA vanes a couple years back. The above result was experienced in the real world situation, as well as being correctly simulated during simulator training.
We had a few incidents (one causing a RWY overrun) due to stuck AoA vanes a couple years back. The above result was experienced in the real world situation, as well as being correctly simulated during simulator training.
Joined: Feb 2004
Posts: 1,410
Likes: 37
From: Australia
In the 737NG the AOA sensor / alpha vane IS connected to the ADIRU, but according to the schematic NOT to the air data module subsystem.
