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 TM 55-1905-220-14-11
5-117. SHIP'S COURSE INDICATOR-MAINTENANCE INSTRUCTIONS (Continued).
(c) All bearings are factory lubricated and shielded. Accessible bearings may be lubricated yearly with the
same grease as used on the gear train. Since the bearings will operate for many years on the factory lubrication, the
gear train should not be disassembled to lubricate bearings. If a bearing shows signs of looseness or binding, the bearing
should be replaced.
(3) Periodic inspection.
(a) If excessive condensation appears on the underside of the dial window, remove the drain plug and let
condensation escape. Indicators exposed to the weather are likely to have some condensation. If excessive condensation
persists, the cover window gasket is not sealing properly and should be tightened or replaced as necessary.
(b) All gears should be inspected yearly for signs of dirt or corrosion. Check the gear train for binding or
excessive backlash. Clean all gears with varsol and an air hose, and lubricate with MIL-G-3278 or MIL-G-23827 grease.
Replace any worn gears or bearings. Instructions for disassembling the gear train are presented in step 1.
(c) When the SCI is disassembled for lubrication or repairs, check that all electrical connections, synchros
and motor clamps, and all screws are secure. Inspect for visible defects and repair or replace as necessary; otherwise
there are no regular preventive maintenance measures to be taken. If all is well, reassemble the indicator, re-energize it
and observe it for proper response (static error 0.2 and dynamic error 0.5). Familiarity with a properly operating indicator
gained during the first few periodic inspections will enable you to recognize more readily the symptoms of malfunctions
should any develop later.
(4) Troubleshooting procedure.
(a) If the indication of a dial differs signficantly from that of the master compass or other equipment that supplies
data to a ship's course indicator, or if the dial holds a fixed position during course changes, moves abruptly to another
position, or if the indicator otherwise behaves abnormally, inspect the indicator promptly to correct any defect. The
cause of malfunction may, if uncorrected, cause rapid deterioration of the indicator.
(b) First determine that the trouble is in the indicator rather than in the transmitting equipment. This can be done
on an installation with several ship's course indicators by comparing the behavior of all indicators. If they all behave in
the same manner the cause of trouble is in the transmitting equipment.
5-1315
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