FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 12. Aircraft Avionics Systems | 3. Ground Operational Checks for Avionics Equipment (Non-Electrical) | 12-37. Compass Check Swing
9/27/01
AC 43.13-1B CHG 1
SECTION 3. GROUND OPERATIONAL CHECKS FOR AVIONICS EQUIPMENT
(NON ELECTRICAL)
12-37. COMPASS SWING must be per
formed whenever any ferrous component of
the system (i.e. flux valve compensator, or
Standby Compass) is installed, removed, re
paired, or a new compass is installed. The
magnetic compass can be checked for accuracy
by using a compass rose located on an airport.
The compass swing is normally effected by
placing the aircraft on various magnetic head
ings and comparing the deviations with those
on the deviation cards. Refer to CFR14,
23.1327, 14 CFR 23.1547, and the equipment
or aircraft manufacturer's manual.
a. A compass swing must be performed on
the following occasions:
(1) When the accuracy of the compass
is suspected.
(2) After any cockpit modification or
major replacement involving ferrous metal.
(3) Whenever a compass has been sub
jected to a shock; for example, after a hard
landing or turbulence.
(9) After aircraft has been parked on
one heading for over a year.
(10) When flux valves are replaced.
b. Precautions.
(1) The magnetic compass must be
checked for accuracy in a location free of steel
structures, underground pipes or cables, or
equipment that produces magnetic fields.
(2) Personnel engaged in the compen
sation of the compass shall remove all mag
netic or ferrous material from their possession.
(3) Use only nonmagnetic tools when
adjusting the compass.
(4) Position the aircraft at least 100
yards from any metal object.
(5) All equipment in the aircraft having
any magnetic effect on the compass must be
secured in the position occupied in normal
flight.
(4) After aircraft has passed through a
severe electrical storm.
(5) After lighting strike.
(6) Whenever a change is made to the
electrical system.
(7) Whenever a change of cargo is
likely to affect the compass.
(8) When an aircraft operation is
changed to a different geographic location with
a major change in magnetic deviation. (e.g.,
from Miami, Florida to Fairbanks, Alaska.)
c. Compass Swing Procedures.
(1) Have the aircraft taxied to the
NORTH (0°) radial on the Compass Rose. Use
a hairline sight compass (a reverse reading
compass with a gun sight arrangement
mounted on top of it) to place the aircraft in
the general vicinity. With the aircraft facing
North and the person in the cockpit running
the engine(s) at 1000 rpm, a mechanic, stand
ing approximately 30 feet in front of the air
craft and facing South, “shoots” or aligns the
master compass with the aircraft center line.
Using hand signals, the mechanic signals the
person in the cockpit to make additional ad
justments to align the aircraft with the master
Par 12-38
Page 12-13