PITOT-STATIC/AIR DATA STANDBY INSTRUMENTS -STANDBY AIR DATA MODULE
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PITOT-STATIC/AIR DATA STANDBY INSTRUMENTS -STANDBY AIRSPEED INDICATOR/ALTIMETER
Purpose
The standby airspeed indicator (SASI) and the standby altimeter (SALT) show airspeed and altitude. The standby airspeed indicator and the standby altimeter receive airspeed and altitude information from the standby air data modules (SADMs) through ARINC 429 buses.
Program Pin Configuration
The standby airspeed indicator and the standby altimeter are interchangeable. Program pins determine the function of the air data standby instruments. Install the air data standby instrument in the standby airspeed indicator location to show the standby airspeed indicator format. Install the air data standby instrument in the standby altimeter location to show the standby altimeter format.
The standby airspeed indicator and the standby altimeter can be put in the standby attitude indicator (SAI) position. However, the push button and knob (selector) used on the standby airspeed indicator and standby altimeter have no function when you install the standby instrument in the SAI position. When you put the SAI in the standby altimeter position PROGRAM PIN ERROR shows. When you put the SAI in the standby airspeed indicator position, the airspeed indication shows, but the standby airspeed bug does not show.
Standby Airspeed Bug
Use the standby airspeed bug selector to move the standby airspeed bug. Push the selector to select the airspeed bug on or off. The airspeed bug is off at electrical power-up.
Standby Airspeed Indicator
The standby airspeed indicator range is from 30 to 450 knots. This is the resolution of the indicator:
*
30 to 80 knots in 10 knot increments
*
80 to 250 knots in 5 knot increments
*
250 to 450 knots in 10 knot increments.
Standby Airspeed Indicator NCD
If the standby airspeed indicator detects a no computed data (NCD) condition, the indication is an airspeed of 30 knots. This can occur when the airplane is on the ground and not moving.
Standby Airspeed Indicator Fail
If the standby airspeed indicator or the air data input fails, the indicator goes blank and a fail flag shows in the center of the display. The fail flag is an amber outline box with SPD inside of the box.
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PITOT-STATIC/AIR DATA STANDBY INSTRUMENTS -STANDBY AIRSPEED INDICATOR/ALTIMETER
Integral Light Sensor
There is an integral light sensor at the lower center of each instrument. The integral light sensor measures the amount of light on the front of the standby instrument. The standby instruments adjust the display brightness to the amount of light available.
The standby instruments send brightness data to each other to adjust their brightness.
Remote Light Sensors
Remote light sensors on the P7 glareshield panel supply brightness signals to the standby instruments. The standby instruments use the average of the integral light sensors and remote light sensors values to adjust the display brightness to the amount of light available.
Standby Altimeter
The standby altimeter shows barometric altitude from 250 to 60000 feet in 100 foot major numerical increments, and 20 foot minor graduation marks. A green hatched box shows in the 10000s digit location for altitude below 10000 feet.
Barometric Reference
The barometric selector makes corrections to the barometric indication in inches of mercury (HG) and Hectopascal (HPA). The push button toggles the barometric reference between standard barometric pressure (29.92 in. Hg) and the last setting.
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