FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 12. Aircraft Avionics Systems | 2. Ground Operational Checks for Avionics Equipment (Electrical) | 12-19. Altimeters
9/27/01
AC 43.13-1B CHG 1
(VHF) navigation and communications sys
tems. This system has an automatic test
equipment (ATE).
NOTE: Aircraft must be outside of
hangar for LORAN to operate.
ment flight rule (IFR) are required to have
their static system(s) and each altimeter in
strument inspected and tested within the previ
ous 24 calendar months. Frequent functional
checks of all altimeters and automatic pressure
altitude reporting systems are recommended.
Normally self test check units, verification of
position, and loading of flight plan will verify
operation verification of proper flight manual
supplements and operating handbooks on
board, and proper software status can also be
verified.
12-17. GLOBAL
POSITIONING
SYSTEM (GPS). The GPS is at the forefront
of present generation navigation systems. This
space-based navigation system is based on a
24-satellite system and is highly accurate
(within 100 meters) for establishing position.
The system is unaffected by weather and pro
vides a world-wide common grid reference
system. Database updating and antenna main
tenance are of primary concern to the GPS
user.
NOTE: Aircraft must be outside of
hangar for ground test of GPS.
12-18. AUTOPILOT SYSTEMS. Auto
matic Flight Control Systems (AFCS) are the
most efficient managers of aircraft perform
ance and control. There are three kinds of
autopilot; two axes, three axes, and three axes
with coupled approach capability. Attention
must be given to the disconnect switch opera
tion, aural and visual alerts of automatic and
intentional autopilot disconnects, override
forces and mode annunciation, servo opera
tion, rigging and bridle cable tension, and con
dition. In all cases the manufacturer’s inspec
tion and maintenance instructions must be
followed.
12-19. ALTIMETERS. Aircraft conducting
operations in controlled airspace under instru
a. The tests required must be performed
by:
(1) The manufacturer of the aircraft on
which the tests and inspection are to be per
formed.
(2) A certificated repair station properly
equipped to perform those functions and
holding:
(a) An instrument rating Class I.
(b) A limited instrument rating ap
propriate to the make and model of appliance
to be tested.
(c) A certified/qualified mechanic
with an airframe rating(static system tests and
inspections only). Any adjustments shall be
accomplished only by an instrument shop cer
tified/qualified person using proper test
equipment and adequate reference to the
manufacturer’s maintenance manuals. The
altimeter correlation adjustment shall not be
adjusted in the field. Changing this adjustment
will nullify the correspondence between the
basic test equipment calibration standards and
the altimeter. It will also nullify correspon
dence between the encoding altimeter and its
encoding digitizer or the associated blind en
coder.
b. Examine the altimeter face for evi
dence of needle scrapes or other damage.
Check smoothness of operation, with particu
lar attention to altimeter performance during
decent.
c. Contact an appropriate air traffic fa-
cility for the pressure altitude displayed to the
controller from your aircraft. Correct the re
ported altitude as needed, and compare to the
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