Narco Avionics AR850 Installation And Operation Manual - page 25
INSTALLATION
SECTION 2
7/03
2-13
2.
Attach the vacuum/pressure pump system and set up the altitude
reporter/transponder test equipment.
3.
Adjust the altimeter barometric setting to 29.92 inches of mercury so
the altimeter hands correspond with the altitude reporter's data
output.
4.
Pump the altimeter and altitude reporter or static system between -500
and +7000 ft. Verify at several test points (chosen by checking
technician), after AR850 data transition, that the altimeter reads
within ±125 ft. of the reported altitude transmitted by the
transponder. If the altimeter correspondence exceeds 125 ft., altimeter
calibration should be suspected.
The zero foot calibration may be adjusted as follows:
NOTE : Low and high altitude adjustments are accessible thru marked
holes in the dust cover.
Pump the system such that the altimeter reads -50 feet. Adjust the low
ALT pot. until the reported code flickers between -100 and 0 feet
(codes 0660 & 0620). This adjustment affects the calibration at all
altitudes and must be done first.
5.
Pump the system between 7000 and 30,700 ft. Verify at several chosen
test altitudes, after transition, the altimeter reads within 125 feet
of the reported altitude. If the correspondence is acceptable, go to
steps 9 and 10; if not, go to step 6.
6.
Adjustment of correspondence above +7000 feet.
a. Pump the system to make the altimeter read 30,650 ft.
b. Adjust the High ALT to make the transponder read alternately
30,600 to 30,700 ft.
c. Check Correspondence at 10,050, 15,050 and 19,950 ft.
7.
Recheck the -50 ft. calibration and adjust if necessary.
8.
Repeat step 6. If correspondence is not acceptable, altimeter
calibration should be suspected.
9.
Turn transponder to Mode A only. Ensure there are only framing pulses
(F1 and F2) present.
10.
Conduct an aircraft static leak test at the conclusion of
correspondence tests.
11. Placard Placement and Alteration
a)
The placard should be prominently displayed on the aircraft
instrument panel.
b)
If the tested altitude is less than 30,700 feet, the placard
should be altered by inserting the altitude tested after
"OPERABLE TO".