Mini-X Installation, Setup & User Manual GRT Avionics
Revision A9 33
4.9 Full Altimeter Calibration – Using Air Data Test Set
This calibration adjusts the relationship between the altitude display and the barometric pressure
setting using an Altimeter Test Set.
1. Turn on the Mini and allow at least 5 minutes to elapse before continuing.
2. Connect test set to the pitot AND static ports of the Mini.
3. Set the test set to sea level (0').
4. From the PFD page, use the knob to adjust the baroset to 29.92 on the Mini.
5. Access Set Menu > Altimeter Calibration.
6. Verify the baroset is 29.92.
7. Use the knob to highlight the Bias setting. Temporarily adjust the Bias setting until the altimeter
reads 0 feet.
8. Set the altimeter test set to 30,000 ft and note the Mini altimeter reading.
9. Calculate the scale factor as follows:
Calculate the Altitude Error as:
Altitude_Error
= GRT Sport_Altimeter_Reading with test set at 30,000 ft.
�
If the Mini altitude is less than 30000 ft, the
Altitude Error
is negative.
�
Calculate the
Pressure Error
by multiplying the
Altitude Error
by 0.819. The result will be a
negative number.
�
If the Mini altitude is greater than 30000 ft, the
Altitude Error
is Positive.
�
Calculate the
Pressure Error
by multiplying the
Altitude Error
by 0.795. The result will be a
positive number.
The scale factor is then calculated as follows:
�
Alt Scale Factor
= 42012 / (42012 +
Pressure Error
)
�
The result should be a number greater than 0.9744, and less than 1.0255
�
Set the
Alt Scale Factor
as calculated.
(Current Mini software may show
ERROR
next to
Calibrate
. This can be ignored.)