(20)
 Calculate and record E-W single cycle error coefficient (B) for

______________________________________
 compass systems (B1, B2 and BS):
 B1 = E1 - W1_______ B2 = E2 - W2_______ BS = ES - WS
 2  2 2

 (21)
 To obtain a standby compass indication compensated for E-W single cycle error (CHWS COMP), adjust E-W compensation screw on standby compass to produce a reading equal to: (CHWS COMP) = CHWS - BS

 (22)
 Adjust E-W compensation screws on remote compensators of compass systems 1 and 2 to produce compensated heading indications equal to: (CHW1 COMP) = CHW1 - B1 (CHW2 COMP) = CHW2 - B2

 (23)
 Calculate index error coefficients (A) for compass systems (A1, A2

____________________________
 and AS):
 A1 = N1+S1+E1+W1___________ A2 = N2+S2+E2+W2___________ AS = NS+SS+ES+WS
 4 4  4

 (24) Remove index error of compass systems by realigning magnetic heading sensors (flux valves) to produce readings (CH1 and CH2) equal to: CH1 = (CHW1 COMP) + A1 CH2 = (CHW2 COMP) + A2
 NOTE: To maintain interchangeability of preindexed flux valves,

____ the index error must be removed by realigning the guide-rail alignment fixture on the flux valve mounting bracket. If loss of flux valve alignment should result from inadvertent loosening of the screws holding the flux valve to the indexing plate, the resulting compass system index error should be removed by realignment of the flux valve relative to the indexing plate; alignment of the guide-rail assembly must not be changed.
 B. Twelve-Point Residual Error Swing
 (1)  Perform a 12-point residual error swing, position airplane at 30-degree intervals (0, 30, 60 degrees, etc.). Calculate and record residual deviation error (R( )) for compass systems 1 and 2 (R( )1 and R( )2) and standby compass (R( )S) at each heading:
 R( )1 = MH( ) - CH( )1 R( )2 = MH( ) - CH( )2 R( )S = MH( ) - CH( )S
 EFFECTIVITY

 

 ALL  07 Page 205  Aug 25/9334-21-00
 (2)  Check that residual errors do not exceed 1.7 degrees at each
 heading for compass systems 1 and 2.  If residual errors are
 acceptable, measure and record (in space provided on the remote
 compensators and on aluminum foil marker located on the compensator
 installation bracket) the N-S and E-W compensating voltages set in
 the respective compensator units.  If residual errors exceed 1.7
 degrees, repeat compass swinging.
 (3)  Observe that standby magnetic compass maximum residual deviation
 does not exceed | 8 degrees on each 30-degree heading.
 (4)  Observe that the difference between maximum positive and maximum
 negative deviations for a complete swing does not exceed 10 degrees.
 NOTE:____ If residual deviation is excessive, realign INS and repeat
 compass compensating swing until residual error is within
 tolerance on all compass systems.
 XA  (5)  Attach Magnetic Compass Correction Card with new records to card
 XA  holder beneath standby magnetic compass (Ref Fig. 202).

 EFFECTIVITY

 

 ALL  04 Page 206  Oct 25/9634-21-00
 T33784

XA

RADIO RECEIVERS ON

Magnetic Compass Correction Card and Card Holder
Figure 202

EFFECTIVITYALL

7XA Page 207
34-21-00

Apr 25/80

 MAGNETIC HEADING REFERENCE SYSTEM - ADJUSTMENT/TEST
___________________________________________________

 1. Operational Test - Magnetic Heading Reference System
____________________________________________________
 A. General
 (1)  The MHRS is completely tested by performing an operational test. The only other adjustment/test procedures are a compass swing as required (refer to Maintenance Practices) and adjustment of the N-S and E-W potentiometers on the magnetic compensators when those units are replaced (Ref 34-21-02, Removal/Installation). No system test is necessary.
 B. Referenced Procedures
 (1)  
21-58-00, Adjustment/Test (Operational Test)

 (2)  
24-22-00, Maintenance Practices (Apply Power)

 (3)  
34-41-00, Adjustment/Test (Operational Test)

 C. Equipment and Materials
 (1)  Voltmeter - Simpson Model 260
 D. Prepare for Test
 (1)  
Determine airplane magnetic heading.

 (2)  
Provide electrical power (Ref 24-22-00).

 (3)  
Supply equipment cooling to main equipment center shelves (Ref 21-58-00).
　
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