1.  General
_______
 A.  The flight instrument switching relays are mounted with screws in the flight instrument switching relay panel (P73) in the main equipment center.
 B.  Open flight instrument switching circuit breakers on the electronic circuit breaker panel (P7) before disconnecting a relay and removing it from relay panel. Close circuit breakers after installing relay.
 C.  After installing a relay, ensure its proper operation by performing an MHRS operational test (refer to 34-21-00, MHRS - Adjustment/Test) and observe that magnetic heading signals are properly displayed on captain's and first officer's horizontal situation indicators and radio magnetic indicators.
 EFFECTIVITY

 

 ALL  01 Page 401  Oct 10/7334-21-05
 RADIO MAGNETIC INDICATOR - REMOVAL/INSTALLATION
_______________________________________________

 1.  General
_______
 A.  Four radio magnetic indicators are installed in the airplane, one VOR and one ADF RMI on each pilot's instrument panel. Each instrument mounts in an individual instrument clamp attached to the rear of the flight instrument panel behind the panel cutout. The RMI slips through the cutout and into the clamp from the front of the panel. The clamp constricts around the instrument, holding it in place, as clamp adjusting screws on the front of the panel are tightened.
 B.  After installing RMI, perform radio magnetic indicator test.
 EFFECTIVITY

 

 ALL  11 Page 401  Oct 10/7334-21-06
 RADIO MAGNETIC INDICATOR - ADJUSTMENT/TEST
__________________________________________

 1. Radio Magnetic Indicator Test
_____________________________
 A. Referenced Procedures
 (1)  
21-58-00, Adjustment/Test (Operational Test)

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

 (3)  
34-21-00, Adjustment/Test (Operational Test)

 (4)  
34-41-00, Adjustment/Test (Operational Test)

 B. Prepare for Test
 (1)  
Provide electrical power (Ref 24-22-00).

 (2)  
Supply equipment cooling to main equipment center shelves (Ref 21-58-00).

 CAUTION: IF OPERATED WITHOUT PROPER COOLING, DAMAGE TO ELECTRONIC
_______
 EQUIPMENT COULD RESULT.

 (3)  
Turn on inertial navigation systems No. 1 and No. 2. Ensure that they are operating in the NAV mode with present position inserted. Main power, platform heading and HSI circuit breakers must be closed (Ref 34-41-00).

 (4)  
Set both VOR/ILS-INS switches to VOR/ILS.

 (5)  
On ALL EXCEPT AT ALL,
 set captain's COMPASS switch to CAPT 1 - F/O 2.
 On AT ALL,
 set captain's COMPASS switch to NORM.

 (6)  
On ALL EXCEPT AT ALL, set captain's ATT/COMP STAB switch to CAPT 1 - F/O 2. On AT ALL, set captain's ATTITUDE switch to NORM.

 C. Test Radio Magnetic Indicator
 (1)  
Close all RMI circuit breakers and close magnetic heading reference systems No. 1 and No. 2 circuit breakers.

 (2)  
Allow systems to stabilize.

 (3)  
Observe that heading flag is out of view and compass card indicates present airplane magnetic heading in radio magnetic indicator.

 (4)  
Turn off inertial navigation systems if no longer required (Ref 34-41-00).

 (5)  
Remove equipment cooling if no longer required (Ref 21-58-00).

 (6)  
Remove electrical power if no longer required (Ref 24-22-00).

 EFFECTIVITY

 

 ALL  26 Page 501  Oct 25/8034-21-06
 DEMAGNETIZATION OF AIRPLANE STRUCTURE - MAINTENANCE PRACTICES
_____________________________________________________________

 1.  General
_______
 A.  Errors in the magnetic heading reference system readouts may be caused by magnetization of the leading edge outboard flap linkages. The linkages may become magnetized when the airplane has been exposed to heavy static charges, or has been struck by lightning. Only the three (3) most outboard linkages on each wing are capable of affecting MHRS information.
 B.  A hand-held compass may be used to detect the presence of such magnetic fields, when held in the proximity of the flap linkages with the leading edge outboard flaps extended. A field strength meter must be used to measure any detected magnetization.
 C.  The demagnetization procedure should be performed if the field strength exceeds 100 gauss, at any point on the three most outboard linkages, when the meter is held against and passed along the entire length of the flap linkages.
　
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