Figure 4-23. B-16 Master Sighting Compass Alignment Method.

TM 1-1500-204-23-4 Figure 4-23. B-16 Master Sighting Compass Alignment Method. NOTE When using the Attitude and Heading Reference System (AHRS) or the Inertial Navigation System, locate the aircraft away from magnetic buildings, materials and other structures. (f) Checking compass while flying. The compass may be checked for deviation while flying by comparing the compass heading with a known heading. NOTE Do not compensate compass while in flight. (g) Calibrator set method of compensating. A more precise method for checking the compass is reflected in TM 11-4920-292-15. It may be used if desired and necessary test equipment is available. (4) Replacement criteria. Line maintenance on magnetic compasses consists primarily of compass swinging, replacing burned out light bulbs, and replacement of defective compasses. Compasses will be replaced for any of the following: · Clouded or discolored liquid · Illegible card markings, fading, or loss of luminous paint · Failure of card to rotate freely in a horizontal plane when aircraft is in a normal flying position · Cracked bowl, broken mounting frame, or broken lugs · Erratic action, or failure of compass to respond after proper efforts to compensate · Lubber line loose or misaligned · Air visible in bowl of compass · If the total deviation of the eight headings exceeds 8 degrees p. Remote Indicating Compass. Remote indicating compass compensation, testing, and replacement criteria are explained in the following paragraphs. 4-29