PIPER AIRCRAFT, INC.
PA-28-161, WARRIOR III
MAINTENANCE MANUAL
PAGE 16
Nov 30/06
3H16
34-20-00
(2) Magnetic Heading Compensation / Calibration
(PIR-PPS60191, Rev. New.)
W
ARNING: FAILURE TO CONSULT APPLICABLE VENDOR PUBLICATION(S), WHEN
SERVICING OR INSPECTING VENDOR EQUIPMENT INSTALLED IN PIPER
AIRCRAFT, MAY RENDER THE AIRCRAFT UNAIRWORTHY. (SEE
INTRODUCTION SUPPLEMENTARY PUBLICATIONS.)
Accuracy of the entire heading system is dependent on the location of the flux detector and
proper calibration. Accuracies of plus or minus one degree are possible when care is taken
during installation and calibration. To obtain such results:
The flux detector must be positioned so that it points in the direction of aircraft flight; and,
the north-south and east-west correctors must be adjusted to compensate for extraneous
magnetic fields near the location of the flux detector.
(a) Required Equipment
Instrument Flight Research Corp. RF signal generator NAV-40IL or equivalent.
Characteristics of the signal generator include: Frequency ranges 108 to 118 MHz, 117 to
136 Mhz, 328 to 336 MHz; +1/-0.01% accuracy, output level continuously adjustable from
1 .0uV to 0.1V into a 50 ohm load; 50 ohm output impedance; and internal adjustable or
stepped VOR, LOC, and GS modulation. The RF signal generator should be portable and
convenient for use while sitting in the aircraft cockpit.
(b) Procedure
1 Apply power to the Model ST-180 HSI System. Allow at least three (3) minutes for the
gyro to erect and synchronize.
2
Prior to actual alignment of the flux sensor, turn the aircraft to both north and east
headings. Apply power to electrical equipment such as navigation and beacon lights
and verify that the compass system is not affected.
3 Align the aircraft to an approximate magnetic north heading. On Chart 3, record the
actual magnetic heading and the HSI heading card reading.
4
Determine and record on Chart 3 the deviation between the actual magnetic heading
and the heading card heading. If the heading card reads high, the deviation is a plus.
5
Repeat steps 3
and 4
for east, south, and west headings. Record actual magnetic
headings, heading card readings, and deviations on Chart 3.
6
Plot deviations on the initial deviation graph in Figure 5.
7
Realign the aircraft to north. Adjust the north-south corrector on the Slaving Panel,
for one half of the difference between the north and south deviations. Record the new
deviation for north and south on the initial deviation graph in Figure 5.
8
Realign the aircraft to east. Adjust the east-west corrector on the Slaving Panel, for
one half the difference between the east and west deviations. Record the new
deviation for east and west on the initial deviation graph in Figure 5.
9 If the pattern is not centered around zero, rotate the flux sensor clockwise to correct
for minus deviations or counterclockwise for plus deviations. Plot final deviations on
the final deviation graph in Figure 5.
10 The deviations should now center around the zero reference line of the graph. If the
error exceeds the specified system error limits (± 3°), repeat the complete procedure.
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