LOWER STRUT AND GLAND SEAL
the sequence that require quality assurance verification
REPLACEMENT
before proceeding to the next step. Landing gear doors
may have to be deactivated or disconnected to check for
On most aircraft the piston O-rings and delta rings
proper up lock actuation and gear up clearances.
can be replaced at the organizational level of
Complete alignment includes down-and-locked
maintenance while the strut is installed on the aircraft.
adjustment, up-and-locked adjustment, and proper door
Procedures for replacing the seals in a main gear recoil
operation. Verification of the emergency landing gear
strut at the organizational level of maintenance consist
system operation is normally required in verifying the
of jacking the aircraft in accordance with the applicable
landing gear system. Some MIMs cover the emergency
MIM. Remove the wheel and brake assemblies so that
system as a separate procedure, but a complete
handling of the lower strut is easier. Remove the cap
operational checkout should include the emergency
from the strut filler valve and release the nitrogen
backup system.
pressure from the strut by opening the valve swivel nut
counterclockwise. Remove the necessary wire bundles,
hydraulic lines, etc., that form a connection between the
WARNING
upper cylinder and lower piston of the strut. Remove
Ensure that all personnel involved in landing gear
the up and down lines from the gear actuating cylinder.
maintenance are clear of the landing gear and doors
Connect a hand pump or check and fill stand lines so
and that signals between the person in the cockpit and
that the strut may be retracted to an angle that will allow
the crew leader are clearly understood before raising
the piston to be withdrawn from the cylinder. Cap any
or lowering the landing gear. Failure to do so could
loose lines or fittings to prevent contamination. On
result in personnel injury.
some aircraft, you will have to use a spring compressor
or some other means to release tension on the gear
down lock mechanism so that the gear can be partially
RECOIL STRUT MAINTENANCE
retracted.
According to current maintenance directives,
With the strut cylinder secured in the partially
maintenance of recoil struts (including minor repair
retracted position and all pressure released from the
and miscellaneous parts replacement) should be
strut, the upper and lower torque arms can be
confined to work that can be performed with only
disconnected. Cut the lockwire and remove the lock
partial disassembly of the equipment. Instructions for
screws from the gland nut. Figure 13-13 shows a main
major or complete overhaul are covered in overhaul
gear recoil strut piston. Refer to figure 13-13 while you
instructions manuals for recoil struts, and such work is
read the following seal replacement material.
performed by specialized shops.
Figure 13-13.--Main gear recoil strut piston.
13-13
