Figure 4-23. B-16 Master Sighting Compass Alignment Method.
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.
Checking compass while flying. The
compass may be checked for deviation while flying by
comparing the compass heading with a known heading.
Do not compensate compass while in
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.
Replacement criteria. Line maintenance on
magnetic compasses consists primarily of compass
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
Lubber line loose or misaligned
Air visible in bowl of compass
If the total deviation of the eight
headings exceeds 8 degrees
Remote Indicating Compass. Remote indicating
criteria are explained in the following paragraphs.