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4.5 Dynamic Calibration Adjustment Procedure using the ECP-100
Reference: FAR 91.217; FAA Advisory Circular 43-6B
FAR 91.423; FAR 43-Appendix E and F
FAA TSO-C88a, EASA ETSO-C88a, SAE AS8003
This procedure will allow adjustment to the calibration curve of the SSD120-(XX)N-RS5 or
SSD120-(XX)NE-RS5 using the ECP-100 as an aide in matching the digitizer output to a primary
flight altimeter or NIST traceable pressure standard. This procedure differs significantly from the
Span Adjust Procedure described in §4.4. The Dynamic Calibration Procedure makes
adjustments to the altitude data stored in the digitizer's EEPROM. The technician may make
adjustments to the digitizer error curve in 1000 foot increments, over the entire operating range
with the single exception of the –1000 foot mark. The technician will make the adjustments at the 0
or whole altitude mark,
digitizer will automatically adjust the ICAO parallel altitude data to transition 50 feet prior to the 0
mark. (i.e. the digitizer's ICAO parallel altitude code will transition from 900 to 1000 feet while the
serial altitude data is transmitting 950 feet.)
1. Connect the digitizer, ECP-100, NIST standard or flight altimeter as shown in the Figure 2
and apply power.
2. Slide the ECP-100 CAL. PROGRAM selector to the leftmost PROGRAM position.
3. Apply power to the altitude digitizer and slide the ECP-100 power switch to the on position.
4. Set the altimeter barometric input to 29.92In.Hg. (1013MB). Adjust the static system
pressure and stabilize at the first altitude to be calibrated. The first possible correction for
Trans-Cal digitizers is at 0 feet. All adjustments to the digitizer calibration curve occur at
1000-foot intervals. Use the ALTITUDE UP and ALTITUDE DOWN buttons to adjust the
ECP-100 to the current pressure altitude prior to pushing the INITIATE PROGRAM
pushbutton.
5. Press the INITIATE PROGRAM pushbutton once. THE ECP-100 will enter a digital
correction into the digitizer's EEPROM at the current pressure altitude.
6. Adjust the input pressure to the next 1000-foot increment and adjust the ECP-100 to the
next 1000-foot increment and repeat step 5. Continue repeating throughout the operating
range of the altitude digitizer.
7. Exercise the aircraft's static system over the operating range of the altitude digitizer and,
with increasing and decreasing pressure, verify at a minimum of ten test points that the
altitude digitizer and primary flight altimeter correspond within the ±125 foot tolerance.
Lightly tap the altimeter before each reading to eliminate friction. If correspondence is not
achieved at any test point, the altimeter may require calibration.
8. Verify that the digitizer's output is disabled when the transponder is not in mode "C", or
when the "Altitude Disable" switch is in the off position.
NOTE: If an error is entered into the digitizer, adjust the pressure to the correct altitude and re-enter the correction. To
clear ALL the corrections to the digitizer error curve press the ALTITUDE UP PROGRAM pushbutton once. Then
press and hold the ALTITUDE DOWN button for two seconds.
If the digitizer and flight altimeter are within the ±125-foot requirement then no correction is required.
DO NOT adjust the digitizer high and low potentiometers during or after this procedure.
at the parallel data's nominal transition point. See Figure 1. The
NOT
Page 18 of 57
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