FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 9. Aircraft Systems and Components | 1. Inspection and Maintenance of Landing Gear | 9-6. Emergency Systems
9/27/01
AC 43.13-1B CHG 1
fully retracted, remove the hose, insert the
valve core, lower the gear, and service the strut
with nitrogen to get the proper strut extension.
g. The entire structure of the landing
gear should be closely examined for cracks,
nicks, cuts, corrosion damage, or any other
condition that can cause stress concentrations
and eventual failure. The exposed lower end
of the air-oleo piston is especially susceptible
to damage and corrosion, which can lead to
seal damage, because the strut is compressed
and the piston moves past the strut lower seal,
causing the seal to leak fluid and air. Small
nicks or cuts can be filed and burnished to a
smooth contour, eliminating the point of stress
concentration. If a crack is found in a landing-
gear member, the part must be replaced.
h. All bolts and fittings should be
checked for security and condition. Bolts in
the torque links and shimmy damper tend to
wear and become loose due to the operational
loads placed on them. The nose-wheel
shimmy damper should be checked for proper
operation and any evidence of leaking. All re-
quired servicing should be performed in accor-
dance with the aircraft service manual.
9-5. INSPECTION OF RETRACTABLE
LANDING GEAR. Inspection of the retract-
able landing gear should include all applicable
items mentioned in the inspection for the fixed
gear. In addition, the actuating mechanisms
must be inspected for wear looseness in any
joint, trunnion, or bearing; leakage of fluid
from any hydraulic line or unit; and, smooth-
ness of operation. The operational check is
performed by jacking the aircraft according to
the manufacturer’s instructions and then oper-
ating the gear retracting and extending system.
landing-gear doors should be checked. Im-
proper adjustment of sequence valves may
cause doors to rub against gear structures or
wheels. The manufacturer’s checklist should
be followed to ensure that critical items are
checked. While the aircraft is still on jacks,
the gear can be tested for looseness of mount-
ing points, play in torque links, condition of
the inner strut cylinder, play in wheel bearings,
and play in actuating linkages. Emergency
blow down gear bottles should be inspected for
damage and corrosion and weighed to see if
the bottle is still retaining the charge.
b. Mechanics should be aware that re-
tread tires can be dimensionally bigger than a
“new” tire. While this does not pose a prob-
lem on fixed landing gear aircraft, it may pres-
ent a serious problem when installed on re-
tractable landing gear aircraft. It is strongly
recommended that if a retread tire is installed
on a retractable landing gear aircraft, a retrac-
tion test be performed. With the gear in the
up-and-lock position, the mechanic should
determine that if the tire expands due to high
ambient temperature, heat generated from taxi
and take-off, repeated landings, or heavy
braking, the tire will not expand to the point
that it becomes wedged in the wheel well.
c. The proper operation of the anti-
retraction system should be checked in accor-
dance with the manufacturer’s instructions.
Where safety switches are actuated by the
torque links, the actual time of switch closing
or opening can be checked by removing all air
from the strut and then collapsing the strut. In
every case, the adjustment should be such that
the gear control cannot be placed in the UP po-
sition or that the system cannot operate until
the shock strut is at the full extended position.
a. During the operational test, the
smoothness of operation, effectiveness of up-
and-down locks, operation of the warning
horn, operation of indicating systems, clear-
ance of tires in wheel wells, and operation of
9-6. EMERGENCY SYSTEMS. Exercise
emergency landing gear systems periodically
to ensure proper operation and to prevent in-
activity, dirt, and corrosion from rendering the
system inoperative when needed. Most emer-
Par 9-4
Page 9-3