(2)
Warning light on CIWS annunciator illuminates.
(3)
Erratic or erroneous heading displayed on compass cards.
(4)
Large heading difference between MHRS 1 and MHRS 2.
(5)
Compass cards drift slowly from airplane heading.
(6)
Compass controller annunciator does not remain aligned.
(7)
MHRS-1 will not operate if STANDBY IGNITION switch is not in the NORM position.
2. Prepare for Trouble Shooting
____________________________
A. Verify that all MHRS, PLATF HDG INS, HDG SYNC EXCIT, RMI, HSI, and FLT INST SW RELAYS COMP circuit breakers on panel P7 are closed.
B. Place panel switches as follows:
On ALL EXCEPT AT ALL,
Captain's ATTITUDE/COMP STAB switch to CAPT 1-F/O 2
Captain's COMPASS switch to CAPT 1-F/O 2
Captain's and first officer's VOR-ILS/INS switches to INS
On AT ALL,
Captain's ATTITUDE switch to NORM
Captain's COMPASS switch to NORM
Captain's and first officer's VOR-ILS/INS switches to INS
C. Provide electrical power (Ref 24-22-00, Maintenance Practices (Apply Power)).
D. Ensure that equipment cooling system is operating (21-58-00).
E. Ensure that the INS systems are operating in NAV mode (34-41-00,
Adjustment/Test).
F. Verify that the standby ignition switch on P5 panel is in NORM position and that the STBY IGN and MHRS circuit breakers on panel P6 are closed.
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PROCEDURE 1
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RAD/INS AND OR MAG/TRUE ANNUNCIATORS IN HSI DO NOT INDICATE RAD AND MAG - Operate RAD/INS switch to INS position and observe that compass card and pointers and annunciation shift to INS display. Place RAD/INS switch in RAD position. IF -
NO ANNUNCIATOR CHANGE BUT DISPLAY SHIFTS - Replace HSI (34-41-06) and perform specified test.
PROCEDURE 2
HEADING WARNING FLAG IN HSI AND RMI ARE NOT RETRACTED - If flag is in view on HSI or RMI replace HSI (34-41-06) or RMI (34-21-06) and perform specified test. If flag is in view on all compass indicators of one system, hold compass SYNC/ SLAVED switch in SYNC (DG) position. IF -
COMPASS FLAGS RETRACT WITH SYNC/SLAVED
SWITCH IN SYNC POSITION - CHECK MAGN.
FIELD SENSOR EXCIT. FUSE - IF NORMAL -
Replace in sequence and perform specified test.
1.
Compass Coupler (34-21-03)
2.
Magnetic Compensator (34-21-02)
3.
Magnetic Field Sensor (34-21-01)
FLAGS RETRACT WITH ATTITUDE TRANSFER IN ALTERNATE POSITION - Replace INS navigation unit (34-41-03) and perform specified test.
AIRPLANE INCORPORATING AEB NO. AF 34-326
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AIRPLANE INCORPORATING AEB NO. AF 34-326
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PROCEDURE 4
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MAGNETIC HEADING REFERENCE SYSTEM -___________________________________
MAINTENANCE PRACTICES (COMPASS SWING)_______________________________________
1. General_______
A. The MHRS is calibrated at the factory with a precision compass swing. The magnetic field sensors, magnetic compensators, and compass couplers may be replaced without the need to perform additional compass swings. The preindexed field sensors are aligned to the airframe and the compensators require only that the E-W and N-S potentiometers be preset to their placarded voltage levels. Additional compass swinging will be necessary if the airplane suffers damage or modification to the wingtips in the vicinity of the magnetic field sensors. 中國航空網(wǎng) www.k6050.com 航空翻譯 www.aviation.cn 本文鏈接地址：747飛機(jī)維護(hù)手冊(cè)AMM CHAPTER 34 - NAVIGATION 第34章導(dǎo)航1(129)
